History of dose specification in Brachytherapy: From Threshold Erythema Dose to Computational Dosimetry

NASA Astrophysics Data System (ADS)

Williamson, Jeffrey F.

2006-09-01

This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as a means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.

Simulation evaluation of NIST air-kerma rate calibration standard for electronic brachytherapy.

PubMed

Hiatt, Jessica R; Rivard, Mark J; Hughes, H Grady

2016-03-01

Dosimetry for the model S700 50 kV electronic brachytherapy (eBT) source (Xoft, Inc., a subsidiary of iCAD, San Jose, CA) was simulated using Monte Carlo (MC) methods by Rivard et al. ["Calculated and measured brachytherapy dosimetry parameters in water for the Xoft Axxent x-ray source: An electronic brachytherapy source," Med. Phys. 33, 4020-4032 (2006)] and recently by Hiatt et al. ["A revised dosimetric characterization of the model S700 electronic brachytherapy source containing an anode-centering plastic insert and other components not included in the 2006 model," Med. Phys. 42, 2764-2776 (2015)] with improved geometric characterization. While these studies examined the dose distribution in water, there have not previously been reports of the eBT source calibration methods beyond that recently reported by Seltzer et al. ["New national air-kerma standard for low-energy electronic brachytherapy sources," J. Res. Natl. Inst. Stand. Technol. 119, 554-574 (2014)]. Therefore, the motivation for the current study was to provide an independent determination of air-kerma rate at 50 cm in air K̇air(d=50 cm) using MC methods for the model S700 eBT source. Using CAD information provided by the vendor and disassembled sources, an MC model was created for the S700 eBT source. Simulations were run using the mcnp6 radiation transport code for the NIST Lamperti air ionization chamber according to specifications by Boutillon et al. ["Comparison of exposure standards in the 10-50 kV x-ray region," Metrologia 5, 1-11 (1969)], in air without the Lamperti chamber, and in vacuum without the Lamperti chamber. K̇air(d=50 cm) was determined using the *F4 tally with NIST values for the mass energy-absorption coefficients for air. Photon spectra were evaluated over 2 π azimuthal sampling for polar angles of 0° ≤ θ ≤ 180° every 1°. Volume averaging was averted through tight radial binning. Photon energy spectra were determined over all polar angles in both air and vacuum using

Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry

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

Candela-Juan, C., E-mail: ccanjuan@gmail.com; Vijande, J.; García-Martínez, T.

2015-08-15

Purpose: A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (<100 kVp) x-ray beam dosimetry faces several challenges that need to be addressed. A number of calibration protocols have been published for x-ray beam dosimetry. The media in which measurements are performed are the fundamental difference between them. The aim of this study was to evaluate the surface dose rate of a low-energy x-ray source with small field applicators using different calibration standards and different small-volume ionization chambers, comparing the values and uncertainties of each methodology. Methods: The surface dose rate ofmore » the EBT unit Esteya (Elekta Brachytherapy, The Netherlands), a 69.5 kVp x-ray source with applicators of 10, 15, 20, 25, and 30 mm diameter, was evaluated using the AAPM TG-61 (based on air kerma) and International Atomic Energy Agency (IAEA) TRS-398 (based on absorbed dose to water) dosimetry protocols for low-energy photon beams. A plane parallel T34013 ionization chamber (PTW Freiburg, Germany) calibrated in terms of both absorbed dose to water and air kerma was used to compare the two dosimetry protocols. Another PTW chamber of the same model was used to evaluate the reproducibility between these chambers. Measurements were also performed with two different Exradin A20 (Standard Imaging, Inc., Middleton, WI) chambers calibrated in terms of air kerma. Results: Differences between surface dose rates measured in air and in water using the T34013 chamber range from 1.6% to 3.3%. No field size dependence has been observed. Differences are below 3.7% when measurements with the A20 and the T34013 chambers calibrated in air are compared. Estimated uncertainty (with coverage factor k = 1) for the T34013 chamber calibrated in water is 2.2%–2.4%, whereas it increases to 2.5% and 2.7% for the A20 and T34013 chambers calibrated in air, respectively. The output factors, measured with the PTW

Monte Carlo study of a 60Co calibration field of the Dosimetry Laboratory Seibersdorf.

PubMed

Hranitzky, C; Stadtmann, H

2007-01-01

The gamma radiation fields of the reference irradiation facility of the Dosimetry Laboratory Seibersdorf with collimated beam geometry are used for calibrating radiation protection dosemeters. A close-to-reality simulation model of the facility including the complex geometry of a 60Co source was set up using the Monte Carlo code MCNP. The goal of this study is to characterise the radionuclide gamma calibration field and resulting air-kerma distributions inside the measurement hall with a total of 20 m in length. For the whole range of source-detector-distances (SDD) along the central beam axis, simulated and measured relative air-kerma values are within +/-0.6%. Influences on the accuracy of the simulation results are investigated, including e.g., source mass density effects or detector volume dependencies. A constant scatter contribution from the lead ring-collimator of approximately 1% and an increasing scatter contribution from the concrete floor for distances above 7 m are identified, resulting in a total air-kerma scatter contribution below 5%, which is in accordance to the ISO 4037-1 recommendations.

Brachytherapy dosimetry of 125I and 103Pd sources using an updated cross section library for the MCNP Monte Carlo transport code.

PubMed

Bohm, Tim D; DeLuca, Paul M; DeWerd, Larry A

2003-04-01

Permanent implantation of low energy (20-40 keV) photon emitting radioactive seeds to treat prostate cancer is an important treatment option for patients. In order to produce accurate implant brachytherapy treatment plans, the dosimetry of a single source must be well characterized. Monte Carlo based transport calculations can be used for source characterization, but must have up to date cross section libraries to produce accurate dosimetry results. This work benchmarks the MCNP code and its photon cross section library for low energy photon brachytherapy applications. In particular, we calculate the emitted photon spectrum, air kerma, depth dose in water, and radial dose function for both 125I and 103Pd based seeds and compare to other published results. Our results show that MCNP's cross section library differs from recent data primarily in the photoelectric cross section for low energies and low atomic number materials. In water, differences as large as 10% in the photoelectric cross section and 6% in the total cross section occur at 125I and 103Pd photon energies. This leads to differences in the dose rate constant of 3% and 5%, and differences as large as 18% and 20% in the radial dose function for the 125I and 103Pd based seeds, respectively. Using a partially updated photon library, calculations of the dose rate constant and radial dose function agree with other published results. Further, the use of the updated photon library allows us to verify air kerma and depth dose in water calculations performed using MCNP's perturbation feature to simulate updated cross sections. We conclude that in order to most effectively use MCNP for low energy photon brachytherapy applications, we must update its cross section library. Following this update, the MCNP code system will be a very effective tool for low energy photon brachytherapy dosimetry applications.

Fundamentals of Radiation Dosimetry

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

Bos, Adrie J. J.

The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuringmore » the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.« less

External dose reconstruction for the former village of Metlino (Techa River, Russia) based on environmental surveys, luminescence measurements, and radiation transport modelling.

PubMed

Hiller, M M; Woda, C; Bougrov, N G; Degteva, M O; Ivanov, O; Ulanovsky, A; Romanov, S

2017-05-01

In the first years of its operation, the Mayak Production Association, a facility part of the Soviet nuclear weapons program in the Southern Urals, Russia, discharged large amounts of radioactively contaminated effluent into the nearby Techa River, thus exposing the people living at this river to external and internal radiations. The Techa River Cohort is a cohort intensely studied in epidemiology to investigate the correlation between low-dose radiation and health effects on humans. For the individuals in the cohort, the Techa River Dosimetry System describes the accumulated dose in human organs and tissues. In particular, organ doses from external exposure are derived from estimates of dose rate in air on the Techa River banks which were estimated from measurements and Monte Carlo modelling. Individual doses are calculated in accordance with historical records of individuals' residence histories, observational data of typical lifestyles for different age groups, and age-dependent conversion factors from air kerma to organ dose. The work here describes an experimentally independent assessment of the key input parameter of the dosimetry system, the integral air kerma, for the former village of Metlino, upper Techa River region. The aim of this work was thus to validate the Techa River Dosimetry System for the location of Metlino in an independent approach. Dose reconstruction based on dose measurements in bricks from a church tower and Monte Carlo calculations was used to model the historic air kerma accumulated in the time from 1949 to 1956 at the shoreline of the Techa River in Metlino. Main issues are caused by a change in the landscape after the evacuation of the village in 1956. Based on measurements and published information and data, two separate models for the historic pre-evacuation geometry and for the current geometry of Metlino were created. Using both models, a value for the air kerma was reconstructed, which agrees with that obtained in the Techa

Dose levels of the occupational radiation exposures in Poland based on results from the accredited dosimetry service at the IFJ PAN, Krakow.

PubMed

Budzanowski, Maciej; Kopeć, Renata; Obryk, Barbara; Olko, Paweł

2011-03-01

Individual dosimetry service based on thermoluminescence (TLD) detectors has started its activity at the Institute of Nuclear Physics (IFJ) in Krakow in 1965. In 2002, the new Laboratory of Individual and Environment Dosimetry (Polish acronym LADIS) was established and underwent the accreditation according to the EN-PN-ISO/IEC 17025 standard. Nowadays, the service is based on the worldwide known standard thermoluminescent detectors MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P), developed at IFJ, processed in automatic thermoluminescent DOSACUS or RE2000 (Rados Oy, Finland) readers. Laboratory provides individual monitoring in terms of personal dose equivalent H(p)(10) and H(p)(0.07) in photon and neutron fields, over the range from 0.1 mSv to 1 Sv, and environmental dosimetry in terms of air kerma K(a) over the range from 30 μGy to 1 Gy and also ambient dose equivalent H*(10) over the range from 30 μSv to 1 Sv. Dosimetric service is currently performed for ca. 3200 institutions from Poland and abroad, monitored on quarterly and monthly basis. The goal of this paper is to identify the main activities leading to the highest radiation exposures in Poland. The paper presents the results of statistical evaluation of ∼ 100,000 quarterly H(p)(10) and K(a) measurements performed between 2002 and 2009. Sixty-five per cent up to 90 % of all individual doses in Poland are on the level of natural radiation background. The dose levels between 0.1 and 5 mSv per quarter are the most frequent in nuclear medicine, veterinary and industrial radiography sectors.

Development of a phantom and a methodology for evaluation of depth kerma and kerma index for dental cone beam computed tomography.

PubMed

Batista, W O; Navarro, M V T; Maia, A F

2013-12-01

Basically, all modalities of diagnostic radiology require phantoms suitable for dosimetric evaluations. New technologies frequently arise unaccompanied of tools for dosimetric evaluations and quality control. In this study, a low-cost phantom and a consequent proposed methodology for dosimetric evaluations in cone beam computed tomography (CBCT) were presented. The developed phantom has typical dimensions of the human face, was built in polymethyl methacrylate and filled with water. Three devices with different technological concepts were evaluated and a proposed index, kerma index-height product (PKIH), was defined as an option to the use of air kerma-area product. The results of this study show relatively uniform kerma profiles for scanners with field of views (FOVs) of large diameters and non-uniform for FOVs of small diameters. With regard to the values obtained for the kerma indexes, much higher values were found for the equipment FOVs with small diameter compared with the values of the two other equipment that have larger diameters. The results indicate that (1) there is a need for special phantoms for use in CBCT, (2) the use of P(KA) in the evaluation of protocols on different equipment can lead to false interpretations and (3) the new index is a suitable alternative for the use of P(KA) in CBCT.

Experimental analysis of a novel and low-cost pin photodiode dosimetry system for diagnostic radiology

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

Nazififard, Mohammad, E-mail: nazifi@kashanu.ac.ir; Mahmoudieh, Afshin; Suh, Kune Y.

Silicon PIN photodiode has recently found broad and exciting applications in the ionizing radiation dosimetry. In this study a compact and novel dosimetry system using a commercially available PIN photodiode (BPW34) has been experimentally tested for diagnostic radiology. The system was evaluated with clinical beams routinely used for diagnostic radiology and calibrated using a secondary reference standard. Measured dose with PIN photodiode (Air Kerma) varied from 10 to 430 μGy for tube voltages from 40 to 100 kVp and tube current from 0.4 to 40 mAs. The minimum detectable organ dose was estimated to be 10 μGy with 20% uncertainty.more » Results showed a linear correlation between the PIN photodiode readout and dose measured with standard dosimeters spanning doses received. The present dosimetry system having advantages of suitable sensitivity with immediate readout of dose values, low cost, and portability could be used as an alternative to passive dosimetry system such as thermoluminescent dosimeter for dose measurements in diagnostic radiology.« less

SU-G-IeP3-01: Better Kerma-Area-Product (KAP) Estimation Using the System Parameters in Radiography and Fluoroscopy

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

Kim, D; MacDougall, R

2016-06-15

Purpose: Accurate values for Kerma-Area-Product (KAP) are needed for patient dosimetry and quality control for exams utilizing radiographic and/or fluoroscopic imaging. The KAP measured using a typical direct KAP meter built with parallel-plate transmission ionization chamber is not precise and depends on the energy spectrum of diagnostic x-rays. This study compared the accuracy and reproducibility of KAP derived from system parameters with values measured with a direct KAP meter. Methods: IEC tolerance for displayed KAP is specified up to ± 35% above 2.5 Gy-cm{sup 2} and manufacturer’s specifications are typically ± 25%. KAP values from the direct KAP meter driftsmore » with time leading to replacement or re-calibration. More precise and consistent KAP is achievable utilizing a database of known radiation output for various system parameters. The integrated KAP meter was removed from a radiography system. A total of 48 measurements of air kerma were acquired at x-ray tube potential from 40 to 150 kVp with 10 kVp increment using ion chamber type external dosimeter at free-in-air geometry for four different types of filter combinations following the manufacturer’s service procedure. These data were used to create updated correction factors that determine air kerma computationally for given system parameters. Results of calculated KAP were evaluated against results using a calibrated ion chamber based dosimeter and a computed radiography imaging plate to measure x-ray field size. Results: The accuracy of calculated KAP from the system parameters was better within 4% deviation in all diagnostic x-ray tube potentials tested from 50 to 140 kVp. In contrast, deviations of up to 25% were measured from KAP displayed from the direct KAP meter. Conclusion: The “calculated KAP” approach provides the nominal advantage of improved accuracy and precision of displayed KAP as well as reduced cost of calibrating or replacing integrated KAP meters.« less

Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media.

PubMed

Kumar, Sudhir; Nahum, Alan E

2016-02-07

Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of 'secondary bremsstrahlung' along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV 'clinical' radiotherapy qualities. Concerning depth-dependence, the 'area under the kerma, K, curve' exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the 'double counting' of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma 'liberated' in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this 'violation' amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a 'clinical' 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm−2 for both very high and very low charged-particle transport cut-offs reveals the considerable

Integration of kerma-area product and cumulative air kerma determination into a skin dose tracking system for fluoroscopic imaging procedures

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

2016-03-01

The skin dose tracking system (DTS) that we developed provides a color-coded mapping of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures in real time. The DTS has now been modified to also calculate the kerma area product (KAP) and cumulative air kerma (CAK) for fluoroscopic interventions using data obtained in real-time from the digital bus on a Toshiba Infinix system. KAP is the integral of air kerma over the beam area and is typically measured with a large-area transmission ionization chamber incorporated into the collimator assembly. In this software, KAP is automatically determined for each x-ray pulse as the product of the air kerma/ mAs from a calibration file for the given kVp and beam filtration times the mAs per pulse times the length and width of the beam times a field nonuniformity correction factor. Field nonuniformity is primarily the result of the heel effect and the correction factor was determined from the beam profile measured using radio-chromic film. Dividing the KAP by the beam area at the interventional reference point provides the area averaged CAK. The KAP and CAK per x-ray pulse are summed after each pulse to obtain the total procedure values in real-time. The calculated KAP and CAK were compared to the values displayed by the fluoroscopy machine with excellent agreement. The DTS now is able to automatically calculate both KAP and CAK without the need for measurement by an add-on transmission ionization chamber.

Effects of water on fingernail electron paramagnetic resonance dosimetry.

PubMed

Zhang, Tengda; Zhao, Zhixin; Zhang, Haiying; Zhai, Hezheng; Ruan, Shuzhou; Jiao, Ling; Zhang, Wenyi

2016-09-01

Electron paramagnetic resonance (EPR) is a promising biodosimetric method, and fingernails are sensitive biomaterials to ionizing radiation. Therefore, kinetic energy released per unit mass (kerma) can be estimated by measuring the level of free radicals within fingernails, using EPR. However, to date this dosimetry has been deficient and insufficiently accurate. In the sampling processes and measurements, water plays a significant role. This paper discusses many effects of water on fingernail EPR dosimetry, including disturbance to EPR measurements and two different effects on the production of free radicals. Water that is unable to contact free radicals can promote the production of free radicals due to indirect ionizing effects. Therefore, varying water content within fingernails can lead to varying growth rates in the free radical concentration after irradiation-these two variables have a linear relationship, with a slope of 1.8143. Thus, EPR dosimetry needs to be adjusted according to the water content of the fingernails of an individual. When the free radicals are exposed to water, the eliminating effect will appear. Therefore, soaking fingernail pieces in water before irradiation, as many researchers have previously done, can cause estimation errors. In addition, nails need to be dehydrated before making accurately quantitative EPR measurements. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

New National Air-Kerma-Strength Standards for 125I and 103Pd Brachytherapy Seeds

PubMed Central

Seltzer, Stephen M.; Lamperti, Paul J.; Loevinger, Robert; Mitch, Michael G.; Weaver, James T.; Coursey, Bert M.

2003-01-01

The new U.S. measurement standard for the air-kerma strength from low-energy photon-emitting brachytherapy seed sources is formally described in detail. This instrument-based standard was implemented on 1 January 1999, with its salient features and the implications of differences with the previous standard given only through a series of informal communications. The Wide-Angle Free-Air Chamber (WAFAC) is specially designed to realize air kerma from a single-seed source emitting photons with energies up to about 40 keV, and is now used to measure the wide variety of seeds used in prostate-cancer therapy that has appeared in the last few years. For the two 125I seed models that have been subject to both the old and new standards, the new standard reduces the air-kerma strength by 10.3 %. This change is mainly due to the removal of the influence on the measurement of the Ti K x rays produced in the source encapsulation, a component with no clinical significance. PMID:27413614

All about MAX: a male adult voxel phantom for Monte Carlo calculations in radiation protection dosimetry

NASA Astrophysics Data System (ADS)

Kramer, R.; Vieira, J. W.; Khoury, H. J.; Lima, F. R. A.; Fuelle, D.

2003-05-01

The MAX (Male Adult voXel) phantom has been developed from existing segmented images of a male adult body, in order to achieve a representation as close as possible to the anatomical properties of the reference adult male specified by the ICRP. The study describes the adjustments of the soft-tissue organ masses, a new dosimetric model for the skin, a new model for skeletal dosimetry and a computational exposure model based on coupling the MAX phantom with the EGS4 Monte Carlo code. Conversion coefficients between equivalent dose to the red bone marrow as well as effective MAX dose and air-kerma free in air for external photon irradiation from the front and from the back, respectively, are presented and compared with similar data from other human phantoms.

MO-D-213-07: RadShield: Semi- Automated Calculation of Air Kerma Rate and Barrier Thickness

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

DeLorenzo, M; Wu, D; Rutel, I

2015-06-15

Purpose: To develop the first Java-based semi-automated calculation program intended to aid professional radiation shielding design. Air-kerma rate and barrier thickness calculations are performed by implementing NCRP Report 147 formalism into a Graphical User Interface (GUI). The ultimate aim of this newly created software package is to reduce errors and improve radiographic and fluoroscopic room designs over manual approaches. Methods: Floor plans are first imported as images into the RadShield software program. These plans serve as templates for drawing barriers, occupied regions and x-ray tube locations. We have implemented sub-GUIs that allow the specification in regions and equipment for occupancymore » factors, design goals, number of patients, primary beam directions, source-to-patient distances and workload distributions. Once the user enters the above parameters, the program automatically calculates air-kerma rate at sampled points beyond all barriers. For each sample point, a corresponding minimum barrier thickness is calculated to meet the design goal. RadShield allows control over preshielding, sample point location and material types. Results: A functional GUI package was developed and tested. Examination of sample walls and source distributions yields a maximum percent difference of less than 0.1% between hand-calculated air-kerma rates and RadShield. Conclusion: The initial results demonstrated that RadShield calculates air-kerma rates and required barrier thicknesses with reliable accuracy and can be used to make radiation shielding design more efficient and accurate. This newly developed approach differs from conventional calculation methods in that it finds air-kerma rates and thickness requirements for many points outside the barriers, stores the information and selects the largest value needed to comply with NCRP Report 147 design goals. Floor plans, parameters, designs and reports can be saved and accessed later for modification and

Poster — Thur Eve — 24: Commissioning and preliminary measurements using an Attix-style free air ionization chamber for air kerma measurements on the BioMedical Imaging and Therapy beamlines at the Canadian Light Source

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

Anderson, D; McEwen, M; Shen, H

Synchrotron facilities, including the Canadian Light Source (CLS), provide opportunities for the development of novel imaging and therapy applications. A vital step progressing these applications toward clinical trials is the availability of accurate dosimetry. In this study, a refurbished Attix-style (cylindrical) free air chamber (FAC) is tested and used for preliminary air kerma measurements on the two BioMedical Imaging and Therapy (BMIT) beamlines at the CLS. The FAC consists of a telescoping chamber that relies on a difference measurement of collected charge in expanded and collapsed configurations. At the National Research Council's X-ray facility, a Victoreen Model 480 FAC wasmore » benchmarked against two primary standard FACs. The results indicated an absolute accuracy at the 0.5% level for energies between 60 and 150 kVp. A series of measurements were conducted on the small, non-uniform X-ray beams of the 05B1-1 (∼8 – 100 keV) and 05ID-2 (∼20 – 200 keV) beamlines for a variety of energies, filtrations and beam sizes. For the 05B1-1 beam with 1.1 mm of Cu filtration, recombination corrections of less than 5 % could only be achieved for field sizes no greater than 0.5 mm × 0.6 mm (corresponding to an air kerma rate of ∼ 57 Gy/min). Ionic recombination thus presents a significant challenge to obtaining accurate air kerma rate measurements using this FAC in these high intensity beams. Future work includes measurements using a smaller aperture to sample a smaller and thus more uniform beam area, as well as experimental and Monte Carlo-based investigation of correction factors.« less

WE-H-207A-07: Image-Based Versus Atlas-Based Internal Dosimetry

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

Fallahpoor, M; Abbasi, M; Parach, A

Purpose: Monte Carlo (MC) simulation is known as the gold standard method for internal dosimetry. It requires radionuclide distribution from PET or SPECT and body structure from CT for accurate dose calculation. The manual or semi-automatic segmentation of organs from CT images is a major obstacle. The aim of this study is to compare the dosimetry results based on patient’s own CT and a digital humanoid phantom as an atlas with pre-specified organs. Methods: SPECT-CT images of a 50 year old woman who underwent bone pain palliation with Samarium-153 EDTMP for osseous metastases from breast cancer were used. The anatomicalmore » date and attenuation map were extracted from SPECT/CT and three XCAT digital phantoms with different BMIs (i.e. matched (38.8) and unmatched (35.5 and 36.7) with patient’s BMI that was 38.3). Segmentation of patient’s organs in CT image was performed using itk-SNAP software. GATE MC Simulator was used for dose calculation. Specific absorbed fractions (SAFs) and S-values were calculated for the segmented organs. Results: The differences between SAFs and S-values are high using different anatomical data and range from −13% to 39% for SAF values and −109% to 79% for S-values in different organs. In the spine, the clinically important target organ for Samarium Therapy, the differences in the S-values and SAF values are higher between XCAT phantom and CT when the phantom with identical BMI is employed (53.8% relative difference in S-value and 26.8% difference in SAF). However, the whole body dose values were the same between the calculations based on the CT and XCAT with different BMIs. Conclusion: The results indicated that atlas-based dosimetry using XCAT phantom even with matched BMI for patient leads to considerable errors as compared to image-based dosimetry that uses the patient’s own CT Patient-specific dosimetry using CT image is essential for accurate results.« less

New National Air-Kerma Standard for Low-Energy Electronic Brachytherapy Sources

PubMed Central

Seltzer, Stephen M; O’Brien, Michelle; Mitch, Michael G

2014-01-01

The new primary standard for low-energy electronic brachytherapy sources for the United States is described. These miniature x-ray tubes are inserted in catheters for interstitial radiation therapy and operate at tube potentials of up to about 50 kV. The standard is based on the realization of the air kerma produced by the x-ray beam at a reference distance in air of 50 cm. PMID:26601044

Clinical implementation and rapid commissioning of an EPID based in-vivo dosimetry system.

PubMed

Hanson, Ian M; Hansen, Vibeke N; Olaciregui-Ruiz, Igor; van Herk, Marcel

2014-10-07

Using an Electronic Portal Imaging Device (EPID) to perform in-vivo dosimetry is one of the most effective and efficient methods of verifying the safe delivery of complex radiotherapy treatments. Previous work has detailed the development of an EPID based in-vivo dosimetry system that was subsequently used to replace pre-treatment dose verification of IMRT and VMAT plans. Here we show that this system can be readily implemented on a commercial megavoltage imaging platform without modification to EPID hardware and without impacting standard imaging procedures. The accuracy and practicality of the EPID in-vivo dosimetry system was confirmed through a comparison with traditional TLD in-vivo measurements performed on five prostate patients.The commissioning time required for the EPID in-vivo dosimetry system was initially prohibitive at approximately 10 h per linac. Here we present a method of calculating linac specific EPID dosimetry correction factors that allow a single energy specific commissioning model to be applied to EPID data from multiple linacs. Using this method reduced the required per linac commissioning time to approximately 30 min.The validity of this commissioning method has been tested by analysing in-vivo dosimetry results of 1220 patients acquired on seven linacs over a period of 5 years. The average deviation between EPID based isocentre dose and expected isocentre dose for these patients was (-0.7  ±  3.2)%.EPID based in-vivo dosimetry is now the primary in-vivo dosimetry tool used at our centre and has replaced nearly all pre-treatment dose verification of IMRT treatments.

Clinical implementation and rapid commissioning of an EPID based in-vivo dosimetry system

NASA Astrophysics Data System (ADS)

Hanson, Ian M.; Hansen, Vibeke N.; Olaciregui-Ruiz, Igor; van Herk, Marcel

2014-10-01

Using an Electronic Portal Imaging Device (EPID) to perform in-vivo dosimetry is one of the most effective and efficient methods of verifying the safe delivery of complex radiotherapy treatments. Previous work has detailed the development of an EPID based in-vivo dosimetry system that was subsequently used to replace pre-treatment dose verification of IMRT and VMAT plans. Here we show that this system can be readily implemented on a commercial megavoltage imaging platform without modification to EPID hardware and without impacting standard imaging procedures. The accuracy and practicality of the EPID in-vivo dosimetry system was confirmed through a comparison with traditional TLD in-vivo measurements performed on five prostate patients. The commissioning time required for the EPID in-vivo dosimetry system was initially prohibitive at approximately 10 h per linac. Here we present a method of calculating linac specific EPID dosimetry correction factors that allow a single energy specific commissioning model to be applied to EPID data from multiple linacs. Using this method reduced the required per linac commissioning time to approximately 30 min. The validity of this commissioning method has been tested by analysing in-vivo dosimetry results of 1220 patients acquired on seven linacs over a period of 5 years. The average deviation between EPID based isocentre dose and expected isocentre dose for these patients was (-0.7  ±  3.2)%. EPID based in-vivo dosimetry is now the primary in-vivo dosimetry tool used at our centre and has replaced nearly all pre-treatment dose verification of IMRT treatments.

ALGEBRA: ALgorithm for the heterogeneous dosimetry based on GEANT4 for BRAchytherapy.

PubMed

Afsharpour, H; Landry, G; D'Amours, M; Enger, S; Reniers, B; Poon, E; Carrier, J-F; Verhaegen, F; Beaulieu, L

2012-06-07

Task group 43 (TG43)-based dosimetry algorithms are efficient for brachytherapy dose calculation in water. However, human tissues have chemical compositions and densities different than water. Moreover, the mutual shielding effect of seeds on each other (interseed attenuation) is neglected in the TG43-based dosimetry platforms. The scientific community has expressed the need for an accurate dosimetry platform in brachytherapy. The purpose of this paper is to present ALGEBRA, a Monte Carlo platform for dosimetry in brachytherapy which is sufficiently fast and accurate for clinical and research purposes. ALGEBRA is based on the GEANT4 Monte Carlo code and is capable of handling the DICOM RT standard to recreate a virtual model of the treated site. Here, the performance of ALGEBRA is presented for the special case of LDR brachytherapy in permanent prostate and breast seed implants. However, the algorithm is also capable of handling other treatments such as HDR brachytherapy.

SU-D-209-01: Can Fluoroscopic Air-Kerma Rates Be Reliably Measured with Solid-State Meters?

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

Feng, C; Thai, L; Wagner, L

Purpose: Ionization chambers remain the standard for calibration of air-kerma rate measuring devices. Despite their strong energy-dependent response, solid state radiation detectors are increasingly used, primarily due to their efficiency in making standardized measurements. To test the reliability of these devices in measuring air-kerma rates, we compared ion chambers measurements with solid-state measurements for various mobile fluoroscopes operated at different beam qualities and air-kerma rates. Methods: Six mobile fluoroscopes (GE OEC models 9800 and 9900) were used to generate test beams. Using various field sizes and dose rate controls, copper attenuators and a lead attenuator were placed at the imagemore » receptor in varying combinations to generate a range of air-kerma rates. Air-kerma rates at 30 centimeters from the image receptors were measured using two 6-cm{sup 3} ion chambers with electrometers (Radcal, models 1015 and 9015) and two with solid state detectors (Unfors Xi and Raysafe X2). No error messages occurred during measurements. However, about two months later, one solid-state device stopped working and was replaced by the manufacturer. Two out of six mobile fluoroscopic units were retested with the replacement unit. Results: Generally, solid state and ionization chambers agreed favorably well, with two exceptions. Before replacement of the detector, the Xi meter when set in the “RF High” mode deviated from ion chamber readings by factors of 2 and 10 with no message indicating error in measurement. When set in the “RF Low” mode, readings were within −4% to +3%. The replacement Xi detector displayed messages alerting the user when settings were not compatible with air-kerma rates. Conclusion: Air-kerma rates can be measured favorably well using solid-state devices, but users must be aware of the possibility that readings can be grossly in error with no discernible indication for the deviation.« less

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

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

Jones, A. Kyle, E-mail: kyle.jones@mdanderson.org; Ensor, Joe E.; Pasciak, Alexander S.

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

Comparison of the NIST and BIPM Medium-Energy X-Ray Air-Kerma Measurements

PubMed Central

Burns, D. T.; O’Brien, M.; Lamperti, P.; Boutillon, M.

2003-01-01

The air-kerma standards used for the measurement of medium-energy x rays were compared at the National Institute of Standards and Technology (NIST) and at the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and two NIST reference-class transfer ionization standards. Reference beam qualities in the range from 60 kV to 300 kV were used. The results show the standards to be in agreement within the combined standard uncertainty of the comparison of 0.35 %. PMID:27413616

Air kerma strength characterization of a GZP6 Cobalt-60 brachytherapy source

PubMed Central

Toossi, Mohammad Taghi Bahreyni; Ghorbani, Mahdi; Mowlavi, Ali Asghar; Taheri, Mojtaba; Layegh, Mohsen; Makhdoumi, Yasha; Meigooni, Ali Soleimani

2010-01-01

Background Task group number 40 (TG-40) of the American Association of Physicists in Medicine (AAPM) has recommended calibration of any brachytherapy source before its clinical use. GZP6 afterloading brachytherapy unit is a 60Co high dose rate (HDR) system recently being used in some of the Iranian radiotherapy centers. Aim In this study air kerma strength (AKS) of 60Co source number three of this unit was estimated by Monte Carlo simulation and in air measurements. Materials and methods Simulation was performed by employing the MCNP-4C Monte Carlo code. Self-absorption of the source core and its capsule were taken into account when calculating air kerma strength. In-air measurements were performed according to the multiple distance method; where a specially designed jig and a 0.6 cm3 Farmer type ionization chamber were used for the measurements. Monte Carlo simulation, in air measurement and GZP6 treatment planning results were compared for primary air kerma strength (as for November 8th 2005). Results Monte Carlo calculated and in air measured air kerma strength were respectively equal to 17240.01 μGym2 h−1 and 16991.83 μGym2 h−1. The value provided by the GZP6 treatment planning system (TPS) was “15355 μGym2 h−1”. Conclusion The calculated and measured AKS values are in good agreement. Calculated-TPS and measured-TPS AKS values are also in agreement within the uncertainties related to our calculation, measurements and those certified by the GZP6 manufacturer. Considering the uncertainties, the TPS value for AKS is validated by our calculations and measurements, however, it is incorporated with a large uncertainty. PMID:24376948

Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality

NASA Astrophysics Data System (ADS)

Helge Østerås, Bjørn; Skaane, Per; Gullien, Randi; Catrine Trægde Martinsen, Anne

2018-02-01

The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra™). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra™. AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.

Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality.

PubMed

Østerås, Bjørn Helge; Skaane, Per; Gullien, Randi; Martinsen, Anne Catrine Trægde

2018-01-25

The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra ™ ). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra ™ . AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.

Dosimetry of 192Ir sources used for endovascular brachytherapy

NASA Astrophysics Data System (ADS)

Reynaert, N.; Van Eijkeren, M.; Taeymans, Y.; Thierens, H.

2001-02-01

An in-phantom calibration technique for 192Ir sources used for endovascular brachytherapy is presented. Three different source lengths were investigated. The calibration was performed in a solid phantom using a Farmer-type ionization chamber at source to detector distances ranging from 1 cm to 5 cm. The dosimetry protocol for medium-energy x-rays extended with a volume-averaging correction factor was used to convert the chamber reading to dose to water. The air kerma strength of the sources was determined as well. EGS4 Monte Carlo calculations were performed to determine the depth dose distribution at distances ranging from 0.6 mm to 10 cm from the source centre. In this way we were able to convert the absolute dose rate at 1 cm distance to the reference point chosen at 2 mm distance. The Monte Carlo results were confirmed by radiochromic film measurements, performed with a double-exposure technique. The dwell times to deliver a dose of 14 Gy at the reference point were determined and compared with results given by the source supplier (CORDIS). They determined the dwell times from a Sievert integration technique based on the source activity. The results from both methods agreed to within 2% for the 12 sources that were evaluated. A Visual Basic routine that superimposes dose distributions, based on the Monte Carlo calculations and the in-phantom calibration, onto intravascular ultrasound images is presented. This routine can be used as an online treatment planning program.

Validating Fricke dosimetry for the measurement of absorbed dose to water for HDR 192Ir brachytherapy: a comparison between primary standards of the LCR, Brazil, and the NRC, Canada.

PubMed

Salata, Camila; David, Mariano Gazineu; de Almeida, Carlos Eduardo; El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcom

2018-04-05

Two Fricke-based absorbed dose to water standards for HDR Ir-192 dosimetry, developed independently by the LCR in Brazil and the NRC in Canada have been compared. The agreement in the determination of the dose rate from a HDR Ir-192 source at 1 cm in a water phantom was found to be within the k  =  1 combined measurement uncertainties of the two standards: D NRC /D LCR   =  1.011, standard uncertainty  =  2.2%. The dose-based standards also agreed within the uncertainties with the manufacturer's stated dose rate value, which is traceable to a national standard of air kerma. A number of possible influence quantities were investigated, including the specific method for producing the ferrous-sulphate Fricke solution, the geometry of the holder, and the Monte Carlo code used to determine correction factors. The comparison highlighted the lack of data on the determination of G(Fe 3+ ) in this energy range and the possibilities for further development of the holders used to contain the Fricke solution. The comparison also confirmed the suitability of Fricke dosimetry for Ir-192 primary standard dose rate determinations at therapy dose levels.

Validating Fricke dosimetry for the measurement of absorbed dose to water for HDR 192Ir brachytherapy: a comparison between primary standards of the LCR, Brazil, and the NRC, Canada

NASA Astrophysics Data System (ADS)

Salata, Camila; Gazineu David, Mariano; de Almeida, Carlos Eduardo; El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcom

2018-04-01

Two Fricke-based absorbed dose to water standards for HDR Ir-192 dosimetry, developed independently by the LCR in Brazil and the NRC in Canada have been compared. The agreement in the determination of the dose rate from a HDR Ir-192 source at 1 cm in a water phantom was found to be within the k  =  1 combined measurement uncertainties of the two standards: D NRC/D LCR  =  1.011, standard uncertainty  =  2.2%. The dose-based standards also agreed within the uncertainties with the manufacturer’s stated dose rate value, which is traceable to a national standard of air kerma. A number of possible influence quantities were investigated, including the specific method for producing the ferrous-sulphate Fricke solution, the geometry of the holder, and the Monte Carlo code used to determine correction factors. The comparison highlighted the lack of data on the determination of G(Fe3+) in this energy range and the possibilities for further development of the holders used to contain the Fricke solution. The comparison also confirmed the suitability of Fricke dosimetry for Ir-192 primary standard dose rate determinations at therapy dose levels.

Modelling of a holographic interferometry based calorimeter for radiation dosimetry

NASA Astrophysics Data System (ADS)

Beigzadeh, A. M.; Vaziri, M. R. Rashidian; Ziaie, F.

2017-08-01

In this research work, a model for predicting the behaviour of holographic interferometry based calorimeters for radiation dosimetry is introduced. Using this technique for radiation dosimetry via measuring the variations of refractive index due to energy deposition of radiation has several considerable advantages such as extreme sensitivity and ability of working without normally used temperature sensors that disturb the radiation field. We have shown that the results of our model are in good agreement with the experiments performed by other researchers under the same conditions. This model also reveals that these types of calorimeters have the additional and considerable merits of transforming the dose distribution to a set of discernible interference fringes.

TU-F-201-00: Radiochromic Film Dosimetry Update

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

NONE

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

Evaluation of entrance surface air kerma in pediatric chest radiography

NASA Astrophysics Data System (ADS)

Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J. L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

2014-11-01

The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior-posterior (AP) and posterior-anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0-1 y, 1-5 y, 5-10 y, and 10-15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels.

The calibration of a Scanditronix-Wellhöfer thimble chamber for photon dosimetry using the IAEA TRS 277 code of practice.

PubMed

Fourie, O L

2004-03-01

This note investigates the calibration of a Scanditronix-Wellhöfer type FC65-G ionisation chamber to be used in clinical photon dosimetry. The current Adaptation by the Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM) of the IAEA TRS 277 dosimetry protocol makes no provision for this type of chamber. The absorbed dose to air calibration coefficient ND was therefore calculated from the air kerma calibration coefficient NK using the formalism of the IAEA TRS 277 protocol and it is shown that the value of the correction factor kmkatt for the FC65-G chamber is identical to that of the NE 2571 chamber. ND was also determined experimentally from a cross calibration against an NE 2571 dosimetry. It was found that there is a good correspondence between the calculated and measured values. To establish to what extent the ACPSEM Adaptation can be used for the FC65-G chamber, values for the ratio of stopping powers in water and air (Sw,air)Q and the perturbation correction factor pQ were calculated using the TRS 277 protocol. From these results it is shown that over the range of beam qualities TPR20,10 = 0.59 to TPR20,10 = 0.78 the Adaptation can be used for the FC65-G chamber.

High resolution MR based polymer dosimetry versus film densitometry: a systematic study based on the modulation transfer function approach.

PubMed

Berg, A; Pernkopf, M; Waldhäusl, C; Schmidt, W; Moser, E

2004-09-07

Precise methods of modem radiation therapy such as intensity modulated radiotherapy (IMRT), brachytherapy (BT) and high LET irradiation allow for high dose localization in volumes of a few mm3. However, most dosimetry methods-ionization chambers, TLD arrangements or silicon detectors, for example-are not capable of detecting sub-mm dose variations or do not allow for simple dose imaging. Magnetic resonance based polymer dosimetry (MRPD) appears to be well suited to three-dimensional high resolution relative dosimetry but the spatial resolution based on a systematic modulation transfer function (MTF) approach has not yet been investigated. We offer a theoretical construct for addressing the spatial resolution in different dose imaging systems, i.e. the dose modulation transfer function (DMTF) approach, an experimental realization of this concept with a phantom and quantitative comparisons between two dosimetric systems: polymer gel and film dosimetry. Polymer gel samples were irradiated by Co-60 photons through an absorber grid which is characterized by periodic structures of different spatial period (a), the smallest one at width of a/2 = 280 microm. The modulation in dose under the grid is visualized via calibrated, high resolution, parameter-selective (T2) and dose images based on multi-echo MR imaging. The DMTF is obtained from the modulation depth of the spin-spin relaxation time (T2) after calibration. Voxel sizes below 0.04 mm3 could be achieved, which are significantly smaller than those reported in MR based dose imaging on polymer gels elsewhere, using a powerful gradient system and a highly sensitive small birdcage resonator on a whole-body 3T MR scanner. Dose modulations at 22% of maximum dose amplitude could be observed at about 2 line pairs per mm. The polymer DMTF results are compared to those of a typical clinical film-scanner system. This study demonstrates that MR based gel dosimetry at 200 microm pixel resolution might even be superior, with

Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and 137Cs Gamma-Ray Beams

PubMed Central

O’Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

2010-01-01

Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients. PMID:27134777

Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and (137)Cs Gamma-Ray Beams.

PubMed

O'Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

2010-01-01

Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients.

A nephron-based model of the kidneys for macro-to-micro α-particle dosimetry

NASA Astrophysics Data System (ADS)

Hobbs, Robert F.; Song, Hong; Huso, David L.; Sundel, Margaret H.; Sgouros, George

2012-07-01

Targeted α-particle therapy is a promising treatment modality for cancer. Due to the short path-length of α-particles, the potential efficacy and toxicity of these agents is best evaluated by microscale dosimetry calculations instead of whole-organ, absorbed fraction-based dosimetry. Yet time-integrated activity (TIA), the necessary input for dosimetry, can still only be quantified reliably at the organ or macroscopic level. We describe a nephron- and cellular-based kidney dosimetry model for α-particle radiopharmaceutical therapy, more suited to the short range and high linear energy transfer of α-particle emitters, which takes as input kidney or cortex TIA and through a macro to micro model-based methodology assigns TIA to micro-level kidney substructures. We apply a geometrical model to provide nephron-level S-values for a range of isotopes allowing for pre-clinical and clinical applications according to the medical internal radiation dosimetry (MIRD) schema. We assume that the relationship between whole-organ TIA and TIA apportioned to microscale substructures as measured in an appropriate pre-clinical mammalian model also applies to the human. In both, the pre-clinical and the human model, microscale substructures are described as a collection of simple geometrical shapes akin to those used in the Cristy-Eckerman phantoms for normal organs. Anatomical parameters are taken from the literature for a human model, while murine parameters are measured ex vivo. The murine histological slides also provide the data for volume of occupancy of the different compartments of the nephron in the kidney: glomerulus versus proximal tubule versus distal tubule. Monte Carlo simulations are run with activity placed in the different nephron compartments for several α-particle emitters currently under investigation in radiopharmaceutical therapy. The S-values were calculated for the α-emitters and their descendants between the different nephron compartments for both the

Feasibility study on dosimetry verification of volumetric-modulated arc therapy-based total marrow irradiation.

PubMed

Liang, Yun; Kim, Gwe-Ya; Pawlicki, Todd; Mundt, Arno J; Mell, Loren K

2013-03-04

The purpose of this study was to develop dosimetry verification procedures for volumetric-modulated arc therapy (VMAT)-based total marrow irradiation (TMI). The VMAT based TMI plans were generated for three patients: one child and two adults. The planning target volume (PTV) was defined as bony skeleton, from head to mid-femur, with a 3 mm margin. The plan strategy similar to published studies was adopted. The PTV was divided into head and neck, chest, and pelvic regions, with separate plans each of which is composed of 2-3 arcs/fields. Multiple isocenters were evenly distributed along the patient's axial direction. The focus of this study is to establish a dosimetry quality assurance procedure involving both two-dimensional (2D) and three-dimensional (3D) volumetric verifications, which is desirable for a large PTV treated with multiple isocenters. The 2D dose verification was performed with film for gamma evaluation and absolute point dose was measured with ion chamber, with attention to the junction between neighboring plans regarding hot/cold spots. The 3D volumetric dose verification used commercial dose reconstruction software to reconstruct dose from electronic portal imaging devices (EPID) images. The gamma evaluation criteria in both 2D and 3D verification were 5% absolute point dose difference and 3 mm of distance to agreement. With film dosimetry, the overall average gamma passing rate was 98.2% and absolute dose difference was 3.9% in junction areas among the test patients; with volumetric portal dosimetry, the corresponding numbers were 90.7% and 2.4%. A dosimetry verification procedure involving both 2D and 3D was developed for VMAT-based TMI. The initial results are encouraging and warrant further investigation in clinical trials.

SU-F-T-12: Monte Carlo Dosimetry of the 60Co Bebig High Dose Rate Source for Brachytherapy

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

Campos, L T; Almeida, C E V de

Purpose: The purpose of this work is to obtain the dosimetry parameters in accordance with the AAPM TG-43U1 formalism with Monte Carlo calculations regarding the BEBIG 60Co high-dose-rate brachytherapy. The geometric design and material details of the source was provided by the manufacturer and was used to define the Monte Carlo geometry. Methods: The dosimetry studies included the calculation of the air kerma strength Sk, collision kerma in water along the transverse axis with an unbounded phantom, dose rate constant and radial dose function. The Monte Carlo code system that was used was EGSnrc with a new cavity code, whichmore » is a part of EGS++ that allows calculating the radial dose function around the source. The XCOM photon cross-section library was used. Variance reduction techniques were used to speed up the calculation and to considerably reduce the computer time. To obtain the dose rate distributions of the source in an unbounded liquid water phantom, the source was immersed at the center of a cube phantom of 100 cm3. Results: The obtained dose rate constant for the BEBIG 60Co source was 1.108±0.001 cGyh-1U-1, which is consistent with the values in the literature. The radial dose functions were compared with the values of the consensus data set in the literature, and they are consistent with the published data for this energy range. Conclusion: The dose rate constant is consistent with the results of Granero et al. and Selvam and Bhola within 1%. Dose rate data are compared to GEANT4 and DORZnrc Monte Carlo code. However, the radial dose function is different by up to 10% for the points that are notably near the source on the transversal axis because of the high-energy photons from 60Co, which causes an electronic disequilibrium at the interface between the source capsule and the liquid water for distances up to 1 cm.« less

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

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

Carl, W. F.

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

Whole-body voxel-based personalized dosimetry: Multiple voxel S-value approach for heterogeneous media with non-uniform activity distributions.

PubMed

Lee, Min Sun; Kim, Joong Hyun; Paeng, Jin Chul; Kang, Keon Wook; Jeong, Jae Min; Lee, Dong Soo; Lee, Jae Sung

2017-12-14

Personalized dosimetry with high accuracy is becoming more important because of the growing interests in personalized medicine and targeted radionuclide therapy. Voxel-based dosimetry using dose point kernel or voxel S-value (VSV) convolution is available. However, these approaches do not consider medium heterogeneity. Here, we propose a new method for whole-body voxel-based personalized dosimetry for heterogeneous media with non-uniform activity distributions, which is referred to as the multiple VSV approach. Methods: The multiple numbers (N) of VSVs for media with different densities covering the whole-body density ranges were used instead of using only a single VSV for water. The VSVs were pre-calculated using GATE Monte Carlo simulation; those were convoluted with the time-integrated activity to generate density-specific dose maps. Computed tomography-based segmentation was conducted to generate binary maps for each density region. The final dose map was acquired by the summation of N segmented density-specific dose maps. We tested several sets of VSVs with different densities: N = 1 (single water VSV), 4, 6, 8, 10, and 20. To validate the proposed method, phantom and patient studies were conducted and compared with direct Monte Carlo, which was considered the ground truth. Finally, patient dosimetry (10 subjects) was conducted using the multiple VSV approach and compared with the single VSV and organ-based dosimetry approaches. Errors at the voxel- and organ-levels were reported for eight organs. Results: In the phantom and patient studies, the multiple VSV approach showed significant improvements regarding voxel-level errors, especially for the lung and bone regions. As N increased, voxel-level errors decreased, although some overestimations were observed at lung boundaries. In the case of multiple VSVs ( N = 8), we achieved voxel-level errors of 2.06%. In the dosimetry study, our proposed method showed much improved results compared to the single VSV and

SU-E-T-66: A Prototype for Couch Based Real-Time Dosimetry in External Beam Radiotherapy

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

Ramachandran, P

Purpose: The main purpose of this study is to design a prototype for couch-based based real time dosimetry system in external beam radiotherapy Methods: A prototype of 100 ionization chambers was designed on a printed circuit board by etching the copper layer and each ionization chamber was wired to a 50 pin connector. The signals from the two 50 pin connectors collected from the ionization chambers were then transferred to a PXI module from National Instruments. The PXI module houses a current amplifier that amplifies the charge collected from the ionization chamber. The amplified signal is then sent to amore » digital multimeter module for converting the analog signal to digital signal. A software was designed in labview to read and display the signals obtained from the PXI module. A couch attachment frame was designed to house the 100 ionization chamber module. The frame was fixed underneath the treatment couch for measuring the dose during treatment. Resutls: The ionization chamber based prototype dosimetry was tested for simple radiotherapy treatment fields and found to be a useful device for measuring real time dosimetry at the treatment couch plane. This information could be used to assess the delivered dose to a patient during radiotherapy. It could be used as an invivo dosimeter during radiotherapy. Conclusion: In this study, a prototype for couch based real time dosimetry system was designed and tested. The prototype forms a basis for the development of large scale couch based real time dosimetry system that could be used to perform morning QA prior to treatment, assess real time doses delivered to patient and as a device to monitor the output of the treatment beam. Peter MacCallum Cancer Foundation.« less

Air-kerma strength determination of a miniature x-ray source for brachytherapy applications

NASA Astrophysics Data System (ADS)

Davis, Stephen D.

A miniature x-ray source has been developed by Xoft Inc. for high dose-rate brachytherapy treatments. The source is contained in a 5.4 mm diameter water-cooling catheter. The source voltage can be adjusted from 40 kV to 50 kV and the beam current is adjustable up to 300 muA. Electrons are accelerated toward a tungsten-coated anode to produce a lightly-filtered bremsstrahlung photon spectrum. The sources were initially used for early-stage breast cancer treatment using a balloon applicator. More recently, Xoft Inc. has developed vaginal and surface applicators. The miniature x-ray sources have been characterized using a modification of the American Association of Physicists in Medicine Task Group No. 43 formalism normally used for radioactive brachytherapy sources. Primary measurements of air kerma were performed using free-air ionization chambers at the University of Wisconsin (UW) and the National Institute of Standards and Technology (NIST). The measurements at UW were used to calibrate a well-type ionization chamber for clinical verification of source strength. Accurate knowledge of the emitted photon spectrum was necessary to calculate the corrections required to determine air-kerma strength, defined in vacuo. Theoretical predictions of the photon spectrum were calculated using three separate Monte Carlo codes: MCNP5, EGSnrc, and PENELOPE. Each code used different implementations of the underlying radiological physics. Benchmark studies were performed to investigate these differences in detail. The most important variation among the codes was found to be the calculation of fluorescence photon production following electron-induced vacancies in the L shell of tungsten atoms. The low-energy tungsten L-shell fluorescence photons have little clinical significance at the treatment distance, but could have a large impact on air-kerma measurements. Calculated photon spectra were compared to spectra measured with high-purity germanium spectroscopy systems at both UW and

Well-ionization chamber response relative to NIST air-kerma strength standard for prostate brachytherapy seeds.

PubMed

Mitch, M G; Zimmerman, B E; Lamperti, P J; Seltzer, S M; Coursey, B M

2000-10-01

The response of well-ionization chambers to the emissions of 103Pd and 125I radioactive seed sources used in prostate cancer brachytherapy has been measured. Calibration factors relating chamber response (current or dial setting) to measured air-kerma strength have been determined for seeds from nine manufacturers, each with different designs. Variations in well-ionization chamber response relative to measured air-kerma strength have been observed because of differences in the emitted energy spectrum due to both the radionuclide support material (125I seeds) and the mass ratio of 103Pd to 102Pd (103Pd seeds). Obtaining accurate results from quality assurance measurements using well-ionization chambers at a therapy clinic requires knowledge of such differences in chamber response as a function of seed design.

Three-dimensional radiation dosimetry based on optically-stimulated luminescence

NASA Astrophysics Data System (ADS)

Sadel, M.; Høye, E. M.; Skyt, P. S.; Muren, L. P.; Petersen, J. B. B.; Balling, P.

2017-05-01

A new approach to three-dimensional (3D) dosimetry based on optically-stimulated luminescence (OSL) is presented. By embedding OSL-active particles into a transparent silicone matrix (PDMS), the well-established dosimetric properties of an OSL material are exploited in a 3D-OSL dosimeter. By investigating prototype dosimeters in standard cuvettes in combination with small test samples for OSL readers, it is shown that a sufficient transparency of the 3D-OSL material can be combined with an OSL response giving an estimated >10.000 detected photons in 1 second per 1mm3 voxel of the dosimeter at a dose of 1 Gy. The dose distribution in the 3D-OSL dosimeters can be directly read out optically without the need for subsequent reconstruction by computational inversion algorithms. The dosimeters carry the advantages known from personal-dosimetry use of OSL: the dose distribution following irradiation can be stored with minimal fading for extended periods of time, and dosimeters are reusable as they can be reset, e.g. by an intense (bleaching) light field.

An image-based skeletal dosimetry model for the ICRP reference adult female—internal electron sources

NASA Astrophysics Data System (ADS)

O'Reilly, Shannon E.; DeWeese, Lindsay S.; Maynard, Matthew R.; Rajon, Didier A.; Wayson, Michael B.; Marshall, Emily L.; Bolch, Wesley E.

2016-12-01

An image-based skeletal dosimetry model for internal electron sources was created for the ICRP-defined reference adult female. Many previous skeletal dosimetry models, which are still employed in commonly used internal dosimetry software, do not properly account for electron escape from trabecular spongiosa, electron cross-fire from cortical bone, and the impact of marrow cellularity on active marrow self-irradiation. Furthermore, these existing models do not employ the current ICRP definition of a 50 µm bone endosteum (or shallow marrow). Each of these limitations was addressed in the present study. Electron transport was completed to determine specific absorbed fractions to both active and shallow marrow of the skeletal regions of the University of Florida reference adult female. The skeletal macrostructure and microstructure were modeled separately. The bone macrostructure was based on the whole-body hybrid computational phantom of the UF series of reference models, while the bone microstructure was derived from microCT images of skeletal region samples taken from a 45 years-old female cadaver. The active and shallow marrow are typically adopted as surrogate tissue regions for the hematopoietic stem cells and osteoprogenitor cells, respectively. Source tissues included active marrow, inactive marrow, trabecular bone volume, trabecular bone surfaces, cortical bone volume, and cortical bone surfaces. Marrow cellularity was varied from 10 to 100 percent for active marrow self-irradiation. All other sources were run at the defined ICRP Publication 70 cellularity for each bone site. A total of 33 discrete electron energies, ranging from 1 keV to 10 MeV, were either simulated or analytically modeled. The method of combining skeletal macrostructure and microstructure absorbed fractions assessed using MCNPX electron transport was found to yield results similar to those determined with the PIRT model applied to the UF adult male skeletal dosimetry model. Calculated

SU-F-T-33: Air-Kerma Strength and Dose Rate Constant by the Full Monte Carlo Simulations

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

Tsuji, S; Oita, M; Narihiro, N

2016-06-15

Purpose: In general, the air-kerma strength (Sk) has been determined by the energy weighting the photon energy fluence and the corresponding mass-energy absorption coefficient or mass-energy transfer coefficient. Kerma is an acronym for kinetic energy released per unit mass, defined as the sum of the initial kinetic energies of all the charged particles. Monte Carlo (MC) simulations can investigate the kinetic energy of the charged particles after photo interactions and sum the energy. The Sk of {sup 192}Ir source is obtained in the full MC simulation and finally the dose rate constant Λ is determine. Methods: MC simulations were performedmore » using EGS5 with the microSelectron HDR v2 type of {sup 192}Ir source. The air-kerma rate obtained to sum the electron kinetic energy after photoelectric absorption or Compton scattering for transverse-axis distance from 1 to 120 cm with a 10 m diameter air phantom. Absorbed dose in water is simulated with a 30 cm diameter water phantom. The transport cut-off energy is 10 keV and primary photons from the source need two hundred and forty billion in the air-kerma rate and thirty billion in absorbed dose in water. Results: Sk is multiplied by the square of the distance in air-kerma rate and determined by fitting a linear function. The result of Sk is (2.7039±0.0085)*10-{sup −11} µGy m{sup 2} Bq{sup −1} s{sup −1}. Absorbed dose rate in water at 1 cm transverse-axis distance D(r{sub 0}, θ{sub 0}) is (3.0114±0.0015)*10{sup −11} cGy Bq{sup −1} s{sup −1}. Conclusion: From the results, dose rate constant Λ of the microSelectron HDR v2 type of {sup 192}Ir source is (1.1137±0.0035) cGy h{sup −1} U{sup −1} by the full MC simulations. The consensus value conΛ is (1.109±0.012) cGy h{sup −1} U{sup −1}. The result value is consistent with the consensus data conΛ.« less

Determination of the reference air kerma rate for 192Ir brachytherapy sources and the related uncertainty.

PubMed

van Dijk, Eduard; Kolkman-Deurloo, Inger-Karine K; Damen, Patricia M G

2004-10-01

Different methods exist to determine the air kerma calibration factor of an ionization chamber for the spectrum of a 192Ir high-dose-rate (HDR) or pulsed-dose-rate (PDR) source. An analysis of two methods to obtain such a calibration factor was performed: (i) the method recommended by [Goetsch et al., Med. Phys. 18, 462-467 (1991)] and (ii) the method employed by the Dutch national standards institute NMi [Petersen et al., Report S-EI-94.01 (NMi, Delft, The Netherlands, 1994)]. This analysis showed a systematic difference on the order of 1% in the determination of the strength of 192Ir HDR and PDR sources depending on the method used for determining the air kerma calibration factor. The definitive significance of the difference between these methods can only be addressed after performing an accurate analysis of the associated uncertainties. For an NE 2561 (or equivalent) ionization chamber and an in-air jig, a typical uncertainty budget of 0.94% was found with the NMi method. The largest contribution in the type-B uncertainty is the uncertainty in the air kerma calibration factor for isotope i, N(i)k, as determined by the primary or secondary standards laboratories. This uncertainty is dominated by the uncertainties in the physical constants for the average mass-energy absorption coefficient ratio and the stopping power ratios. This means that it is not foreseeable that the standards laboratories can decrease the uncertainty in the air kerma calibration factors for ionization chambers in the short term. When the results of the determination of the 192Ir reference air kerma rates in, e.g., different institutes are compared, the uncertainties in the physical constants are the same. To compare the applied techniques, the ratio of the results can be judged by leaving out the uncertainties due to these physical constants. In that case an uncertainty budget of 0.40% (coverage factor=2) should be taken into account. Due to the differences in approach between the method

TU-F-201-01: General Aspects of Radiochromic Film Dosimetry

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

Niroomand-Rad, A.

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

Effects of aluminum-copper alloy filtration on photon spectra, air kerma rate and image contrast.

PubMed

Gonçalves, Andréa; Rollo, João Manuel Domingos de Almeida; Gonçalves, Marcelo; Haiter Neto, Francisco; Bóscolo, Frab Norberto

2004-01-01

This study evaluated the performance of aluminum-copper alloy filtration, without the original aluminum filter, for dental radiography in terms of x-ray energy spectrum, air kerma rate and image quality. Comparisons of various thicknesses of aluminum-copper alloy in three different percentages were made with aluminum filtration. Tests were conducted on an intra-oral dental x-ray machine and were made on mandible phantom and on step-wedge. Depending on the thickness of aluminum-copper alloy filtration, the beam could be hardened and filtrated. The use of the aluminum-copper alloy filter resulted in reductions in air kerma rate from 8.40% to 47.33%, and indicated the same image contrast when compared to aluminum filtration. Aluminum-copper alloy filtration may be considered a good alternative to aluminum filtration.

A test of the IAEA code of practice for absorbed dose determination in photon and electron beams

NASA Astrophysics Data System (ADS)

Leitner, Arnold; Tiefenboeck, Wilhelm; Witzani, Josef; Strachotinsky, Christian

1990-12-01

The IAEA (International Atomic Energy Agency) code of practice TRS 277 gives recommendations for absorbed dose determination in high energy photon and electron beams based on the use of ionization chambers calibrated in terms of exposure of air kerma. The scope of the work was to test the code for cobalt 60 gamma radiation and for several radiation qualities at four different types of electron accelerators and to compare the ionization chamber dosimetry with ferrous sulphate dosimetry. The results show agreement between the two methods within about one per cent for all the investigated qualities. In addition the response of the TLD capsules of the IAEA/WHO TL dosimetry service was determined.

Dosimetry in dentistry.

PubMed

Asha, M L; Chatterjee, Ingita; Patil, Preeti; Naveen, S

2015-01-01

The purpose of this paper was to review various dosimeters used in dentistry and the cumulative results of various studies done with various dosimeters. Several relevant PubMed indexed articles from 1999 to 2013 were electronically searched by typing "dosimeters", "dosimeters in dentistry", "properties of dosimeters", "thermoluminescent and optically stimulated dosimeters", "recent advancements in dosimetry in dentistry." The searches were limited to articles in English to prepare a concise review on dental dosimetry. Titles and abstracts were screened, and articles that fulfilled the criteria of use of dosimeters in dental applications were selected for a full-text reading. Article was divided into four groups: (1) Biological effects of radiation, (2) properties of dosimeters, (3) types of dosimeters and (4) results of various studies using different dosimeters. The present review on dosimetry based on various studies done with dosimeters revealed that, with the advent of radiographic technique the effective dose delivered is low. Therefore, selection of radiological technique plays an important role in dental dose delivery.

A crack model of the Hiroshima atomic bomb: explanation of the contradiction of "Dosimetry system 1986".

PubMed

Hoshi, M; Endo, S; Takada, J; Ishikawa, M; Nitta, Y; Iwatani, K; Oka, T; Fujita, S; Shizuma, K; Hasai, H

1999-12-01

There has been a large discrepancy between the Dosimetry system 1986 (DS86) and measured data, some of which data in Hiroshima at about 1.5 km ground distance from the hypocenter are about 10 times larger than the calculation. Therefore its causes have long been discussed, since it will change the estimated radiation risks obtained based on the Hiroshima and Nagasaki data. In this study the contradiction was explained by a bare-fission-neutron leakage model through a crack formed at the time of neutron emission. According to the present calculation, the crack has a 3 cm parallel spacing, which is symmetric with respect to the polar axis from the hypocenter to the epicenter of the atomic bomb. We made also an asymmetric opening closing 3/4 of this symmetric geometry, because there are some data which shows asymmetry. In addition, the height of the neutron emission point was elevated 90 m. By using the asymmetric calculation, especially for long distant data located more than 1 km, it was verified that all of the activity data induced by thermal and fast neutrons, were simultaneously explained within the data scattering. The neutron kerma at a typical 1.5 km ground distance increases 3 and 8 times more than DS86 based on the symmetric and asymmetric model, respectively.

Comparison of the NIST and PTB Air-Kerma Standards for Low-Energy X-Rays.

PubMed

O'Brien, Michelle; Bueermann, Ludwig

2009-01-01

A comparison has been made of the air-kerma standards for low-energy x rays at the National Institute of Standards and Technology (NIST) and the Physikalisch-Technische Bundesanstalt (PTB). The comparison involved a series of measurements at the PTB and the NIST using the air-kerma standards and two NIST reference-class transfer ionization chamber standards. Results are presented for the reference radiation beam qualities in the range from 25 kV to 50 kV for low energy x rays, including the techniques used for mammography dose traceability. The tungsten generated reference radiation qualities, between 25 kV and 50 kV used for this comparison, are new to NIST; therefore this comparison will serve as the preliminary comparison for NIST and a verification of the primary standard correction factors. The mammography comparison will repeat two previously unpublished comparisons between PTB and NIST. The results show the standards to be in reasonable agreement within the standard uncertainty of the comparison of about 0.4 %.

Evaluation of a LED-based flatbed document scanner for radiochromic film dosimetry in transmission mode.

PubMed

Lárraga-Gutiérrez, José Manuel; García-Garduño, Olivia Amanda; Treviño-Palacios, Carlos; Herrera-González, José Alfredo

2018-03-01

Flatbed scanners are the most frequently used reading instrument for radiochromic film dosimetry because its low cost, high spatial resolution, among other advantages. These scanners use a fluorescent lamp and a CCD array as light source and detector, respectively. Recently, manufacturers of flatbed scanners replaced the fluorescent lamp by light emission diodes (LED) as a light source. The goal of this work is to evaluate the performance of a commercial flatbed scanner with LED based source light for radiochromic film dosimetry. Film read out consistency, response uniformity, film-scanner sensitivity, long term stability and total dose uncertainty was evaluated. In overall, the performance of the LED flatbed scanner is comparable to that of a cold cathode fluorescent lamp (CCFL). There are important spectral differences between LED and CCFL lamps that results in a higher sensitivity of the LED scanner in the green channel. Total dose uncertainty, film response reproducibility and long-term stability of LED scanner are slightly better than those of the CCFL. However, the LED based scanner has a strong non-uniform response, up to 9%, that must be adequately corrected for radiotherapy dosimetry QA. The differences in light emission spectra between LED and CCFL lamps and its potential impact on film-scanner sensitivity suggest that the design of a dedicated flat-bed scanner with LEDs may improve sensitivity and dose uncertainty in radiochromic film dosimetry. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography

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

Kharrati, Hedi

2005-05-01

In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations andmore » does not exceed 75% for the leakage radiation.« less

Comparison of incident air kerma (ki) of common digital and analog radiology procedures in Kohgiluyeh and Boyer-Ahmad province

NASA Astrophysics Data System (ADS)

Vafapour, Hassan; Salehi, Zaker

2018-03-01

Introduction: Although in many developed countries, Analog radiography (AR) is replaced with digital radiography (DR) but AR is still widely used in many countries included Iran. Therefore, dosimetrically assessment of delivered dose is very important to avoid unnecessary patient dose. Materials and Methods: In this study, all imaging centers in Kohgiluyeh and Boyer-Ahmad were selected. The initial information included the mean kVp and mAs used by the personnel to perform each radiological procedure were gathered through a questionnaire. Barracuda dosimeter was then used to measure Incident air kerma (ki). Data obtained from digital radiography (DR) and analogue radiography (AR) were then analyzed and compared to each other. Results: The mean incident air kerma (ki) for five radiological procedures (chest AP&Lat, Skull AP&Lat, Lumbar spine AP&Lat, Thoracic spine AP&Lat and Pelvis) in digital devices were 0.38&1.34, 2.1&1.94, 4.99&7.83, 4.18& 6.41 and 4.33 mGy and those for analogue devices were 0.7&1.28, 3.05&3.02, 7.25&9.9, 7.125&8.36 and 5.36 mGy, respectively. Discussion and Conclusion: The use of low kVp or high mAs is one of the reasons to increase the incident air kerma (ki) in analogue methods comparing to digital methods in all procedures except the chest (in Lateral view). Also the results, surprisingly, showed that in some of the analogue methods incident air kerma (ki) was less than digital methods which is most probably because of the auto-exposure conditions.

SU-E-I-27: Estimating KERMA Area Product for CT Localizer Images

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

Ogden, K; Greene-Donnelly, K; Bennett, R

2015-06-15

Purpose: To estimate the free-in-air KERMA-Area Product (KAP) incident on patients due to CT localizer scans for common CT exams. Methods: In-plane beam intensity profiles were measured in localizer acquisition mode using OSLs for a 64 slice MDCT scanner (Lightspeed VCT, GE Medical Systems, Waukesha WI). The z-axis beam width was measured as a function of distance from isocenter. The beam profile and width were used to calculate a weighted average air KERMA per unit mAs as a function of intercepted x-axis beam width for objects symmetric about the localizer centerline.Patient areas were measured using manually drawn regions and dividedmore » by localizer length to determine average width. Data were collected for 50 head exams (lateral localizer only), 15 head/neck exams, 50 chest exams, and 50 abdomen/pelvis exams. Mean patient widths and acquisition techniques were used to calculate the weighted average free-in-air KERMA, which was multiplied by the patient area to estimate KAP. Results: Scan technique was 120 kV tube voltage, 10 mA current, and table speed of 10 cm/s. The mean ± standard deviation values of KAP were 120 ± 11.6, 469 ± 62.6, 518 ± 45, and 763 ± 93 mGycm{sup 2} for head, head/neck, chest, and abdomen/pelvis exams, respectively. For studies with AP and lateral localizers, the AP/lateral area ratio was 1.20, 1.33, and 1.24 for the head/neck, chest, and abdomen/pelvis exams, respectively. However, the AP/lateral KAP ratios were 1.12, 1.08, and 1.07, respectively. Conclusion: Calculation of KAP in CT localizers is complicated by the non-uniform intensity profile and z-axis beam width. KAP values are similar to those for simple radiographic exams such as a chest radiograph and represent a small fraction of the x-ray exposure at CT. However, as CT doses are reduced the localizer contribution will be a more significant fraction of the total exposure.« less

APMP key comparison for the measurement of air kerma for 60Co (APMP.RI(I)-K1.1)

NASA Astrophysics Data System (ADS)

Webb, D. V.; Lee, J.-H.; Budiantari, C. T.; Laban, J.; Saito, N.; Srimanoroth, S.; Khaled, N. E.

2016-01-01

The results are reported for an APMP.R(I)-K1.1 comparison that extends the regional comparison of standards for air kerma APMP.R(I)-K1 to several laboratories unable to participate earlier. The comparison was conducted with the goal of supporting the relevant calibration and measurement capabilities (CMCs) planned for publication by the participant laboratories. The comparison was conducted by the pilot laboratory, the Australian Radiation Protection and Nuclear Safety (ARPANSA), Australia, supported by the Institute of Nuclear Energy Research (INER), Taiwan, in a modified ring-shaped arrangement from September 2009 to November 2010, in parallel with an APMP.R(I)-K4 comparison being piloted by the INER. The laboratories that took part in the comparison were the ARPANSA, the Centre of Technology of Radiation Safety and Metrology (PTKMR-BATAN), Indonesia, the Division of Radiation and Medical Devices (DMSC), Thailand, the INER, the National Centre for Radiation Science (NCRS), New Zealand, the National Institute for Standards (NIS), Egypt and the National Metrology Institute of Japan (NMIJ/AIST), Japan. The two primary laboratories, ARPANSA and NMIJ, were chosen as the linking laboratories. Three ionization chambers were used as transfer instruments to be calibrated in terms of air kerma in 60Co radiotherapy beams. The comparison result is based on the ratio between the air kerma calibration coefficients (NK) determined by the participants and the mean of the results of the linking laboratories. The mean comparison ratio was found to be within 0.5 % of the key comparison reference value KCRV. The largest deviation between any two comparison ratios for the three chambers in terms of air kerma was 2.0 %. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE) in terms of the deviations of the results and their associated uncertainties. As a result of this APMP comparison, the BIPM key comparison database (KCDB) should

A quantification of the effectiveness of EPID dosimetry and software-based plan verification systems in detecting incidents in radiotherapy

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

Bojechko, Casey; Phillps, Mark; Kalet, Alan

Purpose: Complex treatments in radiation therapy require robust verification in order to prevent errors that can adversely affect the patient. For this purpose, the authors estimate the effectiveness of detecting errors with a “defense in depth” system composed of electronic portal imaging device (EPID) based dosimetry and a software-based system composed of rules-based and Bayesian network verifications. Methods: The authors analyzed incidents with a high potential severity score, scored as a 3 or 4 on a 4 point scale, recorded in an in-house voluntary incident reporting system, collected from February 2012 to August 2014. The incidents were categorized into differentmore » failure modes. The detectability, defined as the number of incidents that are detectable divided total number of incidents, was calculated for each failure mode. Results: In total, 343 incidents were used in this study. Of the incidents 67% were related to photon external beam therapy (EBRT). The majority of the EBRT incidents were related to patient positioning and only a small number of these could be detected by EPID dosimetry when performed prior to treatment (6%). A large fraction could be detected by in vivo dosimetry performed during the first fraction (74%). Rules-based and Bayesian network verifications were found to be complimentary to EPID dosimetry, able to detect errors related to patient prescriptions and documentation, and errors unrelated to photon EBRT. Combining all of the verification steps together, 91% of all EBRT incidents could be detected. Conclusions: This study shows that the defense in depth system is potentially able to detect a large majority of incidents. The most effective EPID-based dosimetry verification is in vivo measurements during the first fraction and is complemented by rules-based and Bayesian network plan checking.« less

Chemical dosimetry system for criticality accidents.

PubMed

Miljanić, Saveta; Ilijas, Boris

2004-01-01

Ruder Bosković Institute (RBI) criticality dosimetry system consists of a chemical dosimetry system for measuring the total (neutron + gamma) dose, and a thermoluminescent (TL) dosimetry system for a separate determination of the gamma ray component. The use of the chemical dosemeter solution chlorobenzene-ethanol-trimethylpentane (CET) is based on the radiolytic formation of hydrochloric acid, which protonates a pH indicator, thymolsulphonphthalein. The high molar absorptivity of its red form at 552 nm is responsible for a high sensitivity of the system: doses in the range 0.2-15 Gy can be measured. The dosemeter has been designed as a glass ampoule filled with the CET solution and inserted into a pen-shaped plastic holder. For dose determinations, a newly constructed optoelectronic reader has been used. The RBI team took part in the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002, with the CET dosimetry system. For gamma ray dose determination TLD-700 TL detectors were used. The results obtained with CET dosemeter show very good agreement with the reference values.

Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities.

PubMed

Pujades, M C; Granero, D; Vijande, J; Ballester, F; Perez-Calatayud, J; Papagiannis, P; Siebert, F A

2014-12-01

In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for (192)Ir and (60)Co HDR applications to account for several different bunker layouts.For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emitted by (192)Ir and (60)Co will reduce the lead thickness by a factor of five for (192)Ir and ten for (60)Co. This will significantly lighten the door and hence simplify construction and operating requirements for all bunkers.The adaptation proposed in this study to estimate the air-kerma rate at the door depends on the complexity of the maze: it provides good results for bunkers with a maze (i.e. similar to those used for linacs for which the NCRP 151 methodology was developed) but fails for less conventional designs. For those facilities, a specific Monte Carlo study is in order for reasons of safety and cost-effectiveness.

MO-D-BRD-04: NIST Air-Kerma Standard for Electronic Brachytherapy Calibrations

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

Mitch, M.

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of

TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry.

PubMed

Garcia, Marie-Paule; Villoing, Daphnée; McKay, Erin; Ferrer, Ludovic; Cremonesi, Marta; Botta, Francesca; Ferrari, Mahila; Bardiès, Manuel

2015-12-01

The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of a given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit gate offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on gate to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user's imaging requirements and generates automatically command files used as input for gate. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant gate input files are generated for the virtual patient model and associated pharmacokinetics. Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body "step and shoot" acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry computation performed on the ICRP 110

Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate.

PubMed

Kowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro

2014-12-01

The 6- to 7-MeV high-energy gamma-ray calibration field by the (19)F(p, αγ)(16)O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma-ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Changes in the U.S. Primary Standards for the Air Kerma From Gamma-Ray Beams

PubMed Central

Seltzer, Stephen M.; Bergstrom, Paul M.

2003-01-01

Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from 60Co, 137Cs, and 192Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for 60Co beams, +0.64 % to +1.07 % (depending on the chamber) for 137Cs beams, and −0.06 % for the single chamber used in the measurement of the standardized 192Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work. PMID:27413615

Changes in the U.S. Primary Standards for the Air Kerma From Gamma-Ray Beams.

PubMed

Seltzer, Stephen M; Bergstrom, Paul M

2003-01-01

Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from (60)Co, (137)Cs, and (192)Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for (60)Co beams, +0.64 % to +1.07 % (depending on the chamber) for (137)Cs beams, and -0.06 % for the single chamber used in the measurement of the standardized (192)Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work.

Comparison of the NIST and NPL Air Kerma Standards Used for X-Ray Measurements Between 10 kV and 80 kV

PubMed Central

O’Brien, M.; Lamperti, P.; Williams, T.; Sander, T.

2000-01-01

A direct comparison was made between the air kerma primary standards used for the measurements of low-energy x rays at the National Institute of Standards and Technology (NIST) and the National Physical Laboratory (NPL). The comparison was conducted at the NPL using NPL reference radiation qualities between 10 kV and 80 kV. The results show the primary air-kerma standards to agree within 0.6 % of their values for beam qualities up to 80 kV. PMID:27551632

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

Anderson, Danielle; Siegbahn, Albert; Fallone, Gin

Purpose: The BioMedical Imaging and Therapy (BMIT) beamlines at the Canadian Light Source offer the opportunity for investigating novel imaging and therapy applications of synchrotron radiation. A necessary component in advancing this research, and in progressing toward clinical applications, is the availability of accurate dosimetry that is traceable to a standards institution. However, dosimetry in this setting is challenging. These beams are typically small, non-uniform, and highly intense. This work describes air kerma rate measurements on a BMIT beamline using a free-air ionization chamber (FAC). Methods: The measurements were taken at the 05B1-1 beamline (∼8 – 100 keV) for severalmore » beam qualities with mean energies between 20.0 and 84.0 keV. The Victoreen Model 480 cylindrical FAC, with a specially fabricated 0.52 mm diameter aperture, was used to measure air kerma rates. The required correction factors were determined using a variety of methods: tabulated data, measurements, theoretical calculations and Monte Carlo simulations (EGSnrc user code egs-fac). Results: The experimental air kerma rates measured between 0.270 ± 13.6% and 312 ± 2.7% Gy/min. At lower energies (low filtration), the most impactful correction factors were those for ion recombination and for x-ray attenuation. Conclusions: These measurements marked the first absolute dosimetry performed at the BMIT beamlines. The experimental and Monte Carlo methods developed will allow air kerma rates to be measured under other experimental conditions, provide a benchmark to which other dosimeters will be compared, and provide a reference for imaging and therapy research programs on this beamline.« less

Seasonal variation of air kerma in the "Vulcano Porto" area (Aeolian Islands, Italy).

PubMed

Bellia, S; Basile, S; Brai, M; Hauser, S; Puccio, P; Rizzo, S

2001-04-01

Air kerma was measured in the "Vulcano Porto" area of the Vulcano Island, belonging to the Aeolian Islands, in the Mediterranean Sea. Measurements were carried out using thermoluminescence dosimeters. The relationship between observed dose values and source lithology has been assessed. Data show a seasonal variation due to weather conditions but also probably related to features of the soils, making the variation more evident.

Use of aspartame-based sweetener tablets in emergency dosimetry using EPR.

PubMed

Maghraby, A; Salama, E

2010-06-01

Accident dosimetry aims to evaluate the unplanned radiation doses delivered to individuals through one of the objects exist in the area of the accident. The gamma dose response of free radicals generated in irradiated aspartame tablets and its usability for emergency dosimetry was studied. EPR spectra of unirradiated and irradiated aspartame-based sweetener were recorded. Two signals arise after irradiating, S(1) at g (S(1)) = 2.00229 +/- 0.00097 and S(2) at g (S(2)) = 2.00262 +/- 0.00088. Some EPR parameters were studied for radiation-induced radicals in aspartame sweeteners tablets, such as the microwave saturation behaviour, the effect of magnetic field modulation amplitude on the peak-to-peak height and peak-to-peak line width for both of S(1) and S(2). Responses of S(1) and S(2) to different radiation doses were studied and resulted in linear relationships, radicals persistence curves were plotted over a 49-d storage period. It was found that Aspartame sweeteners tablets are useful in the range from 0.96 to 39.96 Gy. Radiation-induced radicals possess reasonable stability.

SU-F-T-562: Validation of EPID-Based Dosimetry for FSRS Commissioning

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

Song, Y; Saleh, Z; Obcemea, C

Purpose: The prevailing approach to frameless SRS (fSRS) small field dosimetry is Gafchromic film. Though providing continuous information, its intrinsic uncertainties in fabrication, response, scan, and calibration often make film dosimetry subject to different interpretations. In this study, we explored the feasibility of using EPID portal dosimetry as a viable alternative to film for small field dosimetry. Methods: Plans prescribed a dose of 21 Gy were created on a flat solid water phantom with Eclipse V11 and iPlan for small static square fields (1.0 to 3.0 cm). In addition, two clinical test plans were computed by employing iPlan on amore » CIRS Kesler head phantom for target dimensions of 1.2cm and 2.0cm. Corresponding portal dosimetry plans were computed using the Eclipse TPS and delivered on a Varian TrueBeam machine. EBT-XD film dosimetry was performed as a reference. The isocenter doses were measured using EPID, OSLD, stereotactic diode, and CC01 ion chamber. Results: EPID doses at the center of the square field were higher than Eclipse TPS predicted portal doses, with the mean difference being 2.42±0.65%. Doses measured by EBT-XD film, OSLD, stereotactic diode, and CC01 ion chamber revealed smaller differences (except OSLDs), with mean differences being 0.36±3.11%, 4.12±4.13%, 1.7±2.76%, 1.45±2.37% for Eclipse and −1.36±0.85%, 2.38±4.2%, −0.03±0.50%, −0.27±0.78% for iPlan. The profiles measured by EPID and EBT-XD film resembled TPS (Eclipse and iPlan) predicted ones within 3.0%. For the two clinical test plans, the EPID mean doses at the center of field were 2.66±0.68% and 2.33±0.32% higher than TPS predicted doses. Conclusion: We found that results obtained with EPID portal dosimetry were slightly higher (∼2%) than those obtained with EBT-XD film, diode, and CC01 ion chamber with the exception of OSLDs, but well within IROC tolerance (5.0%). Therefore, EPID has the potential to become a viable real-time alternative method to film

MO-B-BRB-04: 3D Dosimetry in End-To-End Dosimetry QA

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

Ibbott, G.

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

Effect of bedside shielding on air-kerma rates around gynecologic intracavitary brachytherapy patients containing sup 226 Ra or sup 137 Cs

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

Papin, P.J.; Ramsey, M.J.; LaFontaine, R.L.

An anthropomorphic phantom was implanted with 226Ra or 137Cs gynecologic intracavitary brachytherapy sources. Air-kerma rate measurements were taken at 10-cm increments along a horizontal plane from the side of the bed at 50 cm, 87 cm, and 136 cm heights above the floor. Five portable lead shields were placed at the head, at the foot and along one side of the bed and readings were taken again at the corresponding heights above, below and behind the shields. The readings were normalized to 100-mg Ra equivalence, and air-kerma rate curves were drawn allowing for the comparison of 226Ra and 137Cs withmore » and without lead shields. The data demonstrated that the air-kerma rates for 137Cs were reduced more than those for 226Ra with the use of the portable lead shields. There was four times the transmission with 226Ra than with 137Cs. The optimal placement was with the lateral bedside shields proximal to the head and foot closest to the bed, with the middle shield overlapping in back. The shields at the head and foot should extend out and overlap the bedside shields. The level of the sources should be positioned near the bottom of the shields. This information will provide the medical health physicist with an estimate of air-kerma rates for both 226Ra and 137Cs with and without shielding for evaluating personnel exposures as well as the effectiveness of current shielding in relation to radiation protection requirements in adjacent rooms or hallways.« less

New Radiation Dosimetry Estimates for [18F]FLT based on Voxelized Phantoms.

PubMed

Mendes, B M; Ferreira, A V; Nascimento, L T C; Ferreira, S M Z M D; Silveira, M B; Silva, J B

2018-04-25

3'-Deoxy-3-[ 18 F]fluorothymidine, or [ 18 F]FLT, is a positron emission tomography (PET) tracer used in clinical studies for noninvasive assessment of proliferation activity in several types of cancer. Although the use of this PET tracer is expanding, to date, few studies concerning its dosimetry have been published. In this work, new [ 18 F]FLT dosimetry estimates are determined for human and mice using Monte Carlo simulations. Modern voxelized male and female phantoms and [ 18 F]FLT biokinetic data, both published by the ICRP, were used for simulations of human cases. For most human organs/tissues the absorbed doses were higher than those reported in ICRP Publication 128. An effective dose of 1.70E-02 mSv/MBq to the whole body was determined, which is 13.5% higher than the ICRP reference value. These new human dosimetry estimates obtained using more realistic human phantoms represent an advance in the knowledge of [ 18 F]FLT dosimetry. In addition, mice biokinetic data were obtained experimentally. These data and a previously developed voxelized mouse phantom were used for simulations of animal cases. Concerning animal dosimetry, absorbed doses for organs/tissues ranged from 4.47 ± 0.75 to 155.74 ± 59.36 mGy/MBq. The obtained set of organ/tissue radiation doses for healthy Swiss mice is a useful tool for application in animal experiment design.

TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry

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

Garcia, Marie-Paule, E-mail: marie-paule.garcia@univ-brest.fr; Villoing, Daphnée; McKay, Erin

Purpose: The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. Methods: The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of amore » given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit GATE offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on GATE to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user’s imaging requirements and generates automatically command files used as input for GATE. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant GATE input files are generated for the virtual patient model and associated pharmacokinetics. Results: Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body “step and shoot” acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry

TU-G-BRD-04: A Round Robin Dosimetry Intercomparison of Gamma Stereotactic Radiosurgery Calibration Protocols

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

Drzymala, R; Alvarez, P; Bednarz, G

2015-06-15

Purpose: The purpose of this multi-institutional study was to compare two new gamma stereotactic radiosurgery (GSRS) dosimetry protocols to existing calibration methods. The ultimate goal was to guide AAPM Task Group 178 in recommending a standard GSRS dosimetry protocol. Methods: Nine centers (ten GSRS units) participated in the study. Each institution made eight sets of dose rate measurements: six with two different ionization chambers in three different 160mm-diameter spherical phantoms (ABS plastic, Solid Water and liquid water), and two using the same ionization chambers with a custom in-air positioning jig. Absolute dose rates were calculated using a newly proposed formalismmore » by the IAEA working group for small and non-standard radiation fields and with a new air-kerma based protocol. The new IAEA protocol requires an in-water ionization chamber calibration and uses previously reported Monte-Carlo generated factors to account for the material composition of the phantom, the type of ionization chamber, and the unique GSRS beam configuration. Results obtained with the new dose calibration protocols were compared to dose rates determined by the AAPM TG-21 and TG-51 protocols, with TG-21 considered as the standard. Results: Averaged over all institutions, ionization chambers and phantoms, the mean dose rate determined with the new IAEA protocol relative to that determined with TG-21 in the ABS phantom was 1.000 with a standard deviation of 0.008. For TG-51, the average ratio was 0.991 with a standard deviation of 0.013, and for the new in-air formalism it was 1.008 with a standard deviation of 0.012. Conclusion: Average results with both of the new protocols agreed with TG-21 to within one standard deviation. TG-51, which does not take into account the unique GSRS beam configuration or phantom material, was not expected to perform as well as the new protocols. The new IAEA protocol showed remarkably good agreement with TG-21. Conflict of Interests: Paula

Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers

NASA Astrophysics Data System (ADS)

Lye, J. E.; Harty, P. D.; Butler, D. J.; Crosbie, J. C.; Livingstone, J.; Poole, C. M.; Ramanathan, G.; Wright, T.; Stevenson, A. W.

2016-06-01

The absolute dose delivered to a dynamically scanned sample in the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter anticipated to be established as a primary standard for synchrotron dosimetry. The calorimetry was compared to measurements using a free-air chamber (FAC), a PTW 31 014 Pinpoint ionization chamber, and a PTW 34 001 Roos ionization chamber. The IMBL beam height is limited to approximately 2 mm. To produce clinically useful beams of a few centimetres the beam must be scanned in the vertical direction. In practice it is the patient/detector that is scanned and the scanning velocity defines the dose that is delivered. The calorimeter, FAC, and Roos chamber measure the dose area product which is then converted to central axis dose with the scanned beam area derived from Monte Carlo (MC) simulations and film measurements. The Pinpoint chamber measures the central axis dose directly and does not require beam area measurements. The calorimeter and FAC measure dose from first principles. The calorimetry requires conversion of the measured absorbed dose to graphite to absorbed dose to water using MC calculations with the EGSnrc code. Air kerma measurements from the free air chamber were converted to absorbed dose to water using the AAPM TG-61 protocol. The two ionization chambers are secondary standards requiring calibration with kilovoltage x-ray tubes. The Roos and Pinpoint chambers were calibrated against the Australian primary standard for air kerma at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Agreement of order 2% or better was obtained between the calorimetry and ionization chambers. The FAC measured a dose 3-5% higher than the calorimetry, within the stated uncertainties.

The ENEA neutron personal dosimetry service.

PubMed

Morelli, B; Mariotti, F; Fantuzzi, E

2006-01-01

The ENEA Radiation Protection Institute has been operating the only neutron personal dosimetry service in Italy since the 1970s. Since the 1980s the service has been based on PADC (poly allyl diglycol carbonate) for fast neutron dosimetry, while thermal neutron dosimetry has been performed using thermoluminescence (TL) dosemeters. Since the service was started, a number of aspects have undergone evolution. The latest and most important changes are as follows: in 1998 a new PADC material was introduced in routine, since 2001 TL thermal dosimetry has been based on LiF(Mg,Cu,P) [GR-200] and (7)LiF(Mg,Cu,P) [GR-207] detectors and since 2003 a new image analysis reading system for the fast neutron dosemeters has been used. Herein an updated summary of how the service operates and performs today is presented. The approaches to calibration and traceability to estimate the quantity of H(p)(10) are mentioned. Results obtained at the performance test of dosimetric services in the EU member states and Switzerland sponsored by the European Commission and organised by Eurados in 1999 are reported. Last but not least, quality assurance (QA) procedures introduced in the routine operation to track the whole process of dose evaluation (i.e. plastic QA, acceptance test, test etching bath reproducibility and 'dummy customer' (blind test) for each issuing monitoring period) are presented and discussed.

A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy

PubMed Central

Kim, Michele M.; Penjweini, Rozhin; Gemmell, Nathan R.; Veilleux, Israel; McCarthy, Aongus; Buller, Gerald S.; Hadfield, Robert H.; Wilson, Brian C.; Zhu, Timothy C.

2016-01-01

Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT—light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([3O2])—to calculate the amount of reacted singlet oxygen ([1O2]rx), the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD) to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime (τΔ and τt), for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [1O2]rx was compared to SOED-calculated [1O2]rx for various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [1O2]rx using a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM) PDT protocol by using a conversion formula. PMID:27929427

A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy.

PubMed

Kim, Michele M; Penjweini, Rozhin; Gemmell, Nathan R; Veilleux, Israel; McCarthy, Aongus; Buller, Gerald S; Hadfield, Robert H; Wilson, Brian C; Zhu, Timothy C

2016-12-06

Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT-light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([³ O ₂])-to calculate the amount of reacted singlet oxygen ([¹ O ₂] rx ), the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD) to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime ( τ Δ and τ t ), for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [¹ O ₂] rx was compared to SOED-calculated [¹ O ₂] rx for various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [¹ O ₂] rx using a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM) PDT protocol by using a conversion formula.

Proficiency Testing as a tool to monitor consistency of measurements in the IAEA/WHO Network of Secondary Standards Dosimetry Laboratories

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

Meghzifene, Ahmed; Czap, Ladislav; Shortt, Ken

2008-08-14

The International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) established a Network of Secondary Standards Dosimetry Laboratories (IAEA/WHO SSDL Network) in 1976. Through SSDLs designated by Member States, the Network provides a direct link of national dosimetry standards to the international measurement system of standards traceable to the Bureau International des Poids et Mesures (BIPM). Within this structure and through the proper calibration of field instruments, the SSDLs disseminate S.I. quantities and units.To ensure that the services provided by SSDL members to end-users follow internationally accepted standards, the IAEA has set up two different comparison programmes. Onemore » programme relies on the IAEA/WHO postal TLD service and the other uses comparisons of calibrated ionization chambers to help the SSDLs verify the integrity of their national standards and the procedures used for the transfer of the standards to the end-users. The IAEA comparisons include {sup 60}Co air kerma (N{sub K}) and absorbed dose to water (N{sub D,W}) coefficients. The results of the comparisons are confidential and are communicated only to the participants. This is to encourage participation of the laboratories and their full cooperation in the reconciliation of any discrepancy.This work describes the results of the IAEA programme comparing calibration coefficients for radiotherapy dosimetry, using ionization chambers. In this programme, ionization chambers that belong to the SSDLs are calibrated sequentially at the SSDL, at the IAEA, and again at the SSDL. As part of its own quality assurance programme, the IAEA has participated in several regional comparisons organized by Regional Metrology Organizations.The results of the IAEA comparison programme show that the majority of SSDLs are capable of providing calibrations that fall inside the acceptance level of 1.5% compared to the IAEA.« less

Characteristics of The Narrow Spectrum Beams Used in the Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission.

PubMed

Melhem, N; El Balaa, H; Younes, G; Al Kattar, Z

2017-06-15

The Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission has different calibration methods for various types of dosimeters used in industrial, military and medical fields. The calibration is performed using different beams of X-rays (low and medium energy) and Gamma radiation delivered by a Cesium 137 source. The Secondary Standard Dosimetry laboratory in charge of calibration services uses different protocols for the determination of high and low air kerma rate and for narrow and wide series. In order to perform this calibration work, it is very important to identify all the beam characteristics for the different types of sources and qualities of radiation. The following work describes the methods used for the determination of different beam characteristics and calibration coefficients with their uncertainties in order to enhance the radiation protection of workers and patient applications in the fields of medical diagnosis and industrial X-ray. All the characteristics of the X-ray beams are determined for the narrow spectrum series in the 40 and 200 keV range where the inherent filtration, the current intensity, the high voltage, the beam profile and the total uncertainty are the specific characteristics of these X-ray beams. An X-ray software was developed in order to visualize the reference values according to the characteristics of each beam. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Direct calibration of a reference standard against the air kerma strength primary standard, at 192Ir HDR energy.

PubMed

Rajan, K N Govinda; Selvam, T Palani; Bhatt, B C; Vijayam, M; Patki, V S; Vinatha; Pendse, A M; Kannan, V

2002-04-07

The primary standard of low air kerma rate sources or beams, maintained at the Radiological Standards Laboratory (RSL) of the Bhabha Atomic Research Centre (BARC), is a 60 cm3 spherical graphite ionization chamber. A 192Ir HDR source was standardized at the hospital site in units of air kerma strength (AKS) using this primary standard. A 400 cm3 bakelite chamber, functioning as a reference standard at the RSL for a long period, at low air kerma rates (compared to external beam dose rates), was calibrated against the primary standard. It was seen that the primary standard and the reference standard, both being of low Z, showed roughly the same scatter response and yielded the same calibration factor for the 400 cm3 reference chamber, with or without room scatter. However, any likelihood of change in the reference chamber calibration factor would necessitate the re-transport of the primary standard to the hospital site for re-calibration. Frequent transport of the primary standard can affect the long-term stability of the primary standard, due to its movement or other extraneous causes. The calibration of the reference standard against the primary standard at the RSL, for an industrial type 192Ir source maintained at the laboratory, showed excellent agreement with the hospital calibration, making it possible to check the reference chamber calibration at RSL itself. Further calibration procedures have been developed to offer traceable calibration of the hospital well ionization chambers.

MO-FG-CAMPUS-IeP1-04: Kerma Area Product Calculation for Non-Uniform X-Ray Fields Using a Skin Dose Tracking System

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

Vijayan, S; Xiong, Z; Rudin, S

Purpose: The functionality of the Dose-Tracking System (DTS) has been expanded to include the calculation of the Kerma-Area Product (KAP) for non-uniform x-ray fields such as result from the use of compensation filters during fluoroscopic procedures Methods: The DTS calculates skin dose during fluoroscopic interventions and provides a color-coded dose map on a patient-graphic model. The KAP is the integral of air kerma over the x-ray field and is usually measured with a transmission-ionization chamber that intercepts the entire x-ray beam. The DTS has been modified to determine KAP when there are beam non-uniformities that can be modeled. For example,more » the DTS includes models of the three compensation filters with tapered edges located in the collimator assembly of the Toshiba Infinix fluoroscopic C-Arm and can track their movement. To determine the air kerma after the filters, DTS includes transmission factors for the compensation filters as a function of kVp and beam filtration. A virtual KAP dosimeter is simulated in the DTS by an array of graphic vertices; the air kerma at each vertex is corrected by the field non-uniformity, which in this case is the attenuation factor for those rays which pass through the filter. The products of individual vertex air-kerma values for all vertices within the beam times the effective-area-per-vertex are summed for each x-ray pulse to yield the KAP per pulse and the cumulative KAP for the procedure is then calculated. Results: The KAP values estimated by DTS with the compensation filter inserted into the x-ray field agree within ± 6% with the values displayed on the fluoroscopy unit monitor, which are measured with a transmission chamber. Conclusion: The DTS can account for field non-uniformities such as result from the use of compensation filters in calculating KAP and can obviate the need for a KAP transmission ionization chamber. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

Dosimetry procedures for an industrial irradiation plant

NASA Astrophysics Data System (ADS)

Grahn, Ch.

Accurate and reliable dosimetry procedures constitute a very important part of process control and quality assurance at a radiation processing plant. γ-Dose measurements were made on the GBS 84 irradiator for food and other products on pallets or in containers. Chemical dosimeters wre exposed in the facility under conditions of the typical plant operation. The choice of the dosimeter systems employed was based on the experience in chemical dosimetry gained over several years. Dose uniformity information was obtained in air, spices, bulbs, feeds, cosmetics, plastics and surgical goods. Most products currently irradiated require dose uniformity which can be efficiently provided by pallet or box irradiators like GBS 84. The radiation performance characteristics and some dosimetry procedures are discussed.

NOTE: Monte Carlo evaluation of kerma in an HDR brachytherapy bunker

NASA Astrophysics Data System (ADS)

Pérez-Calatayud, J.; Granero, D.; Ballester, F.; Casal, E.; Crispin, V.; Puchades, V.; León, A.; Verdú, G.

2004-12-01

In recent years, the use of high dose rate (HDR) after-loader machines has greatly increased due to the shift from traditional Cs-137/Ir-192 low dose rate (LDR) to HDR brachytherapy. The method used to calculate the required concrete and, where appropriate, lead shielding in the door is based on analytical methods provided by documents published by the ICRP, the IAEA and the NCRP. The purpose of this study is to perform a more realistic kerma evaluation at the entrance maze door of an HDR bunker using the Monte Carlo code GEANT4. The Monte Carlo results were validated experimentally. The spectrum at the maze entrance door, obtained with Monte Carlo, has an average energy of about 110 keV, maintaining a similar value along the length of the maze. The comparison of results from the aforementioned values with the Monte Carlo ones shows that results obtained using the albedo coefficient from the ICRP document more closely match those given by the Monte Carlo method, although the maximum value given by MC calculations is 30% greater.

Air-kerma strength determination of a new directional (103)Pd source.

PubMed

Aima, Manik; Reed, Joshua L; DeWerd, Larry A; Culberson, Wesley S

2015-12-01

A new directional (103)Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing (103)Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active (103)Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S(K)) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S(K) to a well-type ionization chamber. S(K) measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S(K) from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S(K) with the presence of gold fluorescent energy lines. In addition to S(K) measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S(K) values for a directional source within a cylindrically symmetric measurement volume. The UW VAFAC was successfully used to measure the S(K) of four CivaDots with reproducibilities within 0.3%. Monte Carlo

Air-kerma strength determination of a new directional 103Pd source

PubMed Central

Reed, Joshua L.; DeWerd, Larry A.; Culberson, Wesley S.

2015-01-01

Purpose: A new directional 103Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing 103Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active 103Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (SK) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring SK to a well-type ionization chamber. Methods: SK measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity SK from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the mcnp 6 Monte Carlo code in order to determine SK with the presence of gold fluorescent energy lines. In addition to SK measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating SK values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the SK of four CivaDots with reproducibilities within 0.3%. Monte

Evaluation of radiochromic gel dosimetry and polymer gel dosimetry in a clinical dose verification

NASA Astrophysics Data System (ADS)

Vandecasteele, Jan; De Deene, Yves

2013-09-01

A quantitative comparison of two full three-dimensional (3D) gel dosimetry techniques was assessed in a clinical setting: radiochromic gel dosimetry with an in-house developed optical laser CT scanner and polymer gel dosimetry with magnetic resonance imaging (MRI). To benchmark both gel dosimeters, they were exposed to a 6 MV photon beam and the depth dose was compared against a diamond detector measurement that served as golden standard. Both gel dosimeters were found accurate within 4% accuracy. In the 3D dose matrix of the radiochromic gel, hotspot dose deviations up to 8% were observed which are attributed to the fabrication procedure. The polymer gel readout was shown to be sensitive to B0 field and B1 field non-uniformities as well as temperature variations during scanning. The performance of the two gel dosimeters was also evaluated for a brain tumour IMRT treatment. Both gel measured dose distributions were compared against treatment planning system predicted dose maps which were validated independently with ion chamber measurements and portal dosimetry. In the radiochromic gel measurement, two sources of deviations could be identified. Firstly, the dose in a cluster of voxels near the edge of the phantom deviated from the planned dose. Secondly, the presence of dose hotspots in the order of 10% related to inhomogeneities in the gel limit the clinical acceptance of this dosimetry technique. Based on the results of the micelle gel dosimeter prototype presented here, chemical optimization will be subject of future work. Polymer gel dosimetry is capable of measuring the absolute dose in the whole 3D volume within 5% accuracy. A temperature stabilization technique is incorporated to increase the accuracy during short measurements, however keeping the temperature stable during long measurement times in both calibration phantoms and the volumetric phantom is more challenging. The sensitivity of MRI readout to minimal temperature fluctuations is demonstrated which

Optical dosimetry probes to validate Monte Carlo and empirical-method-based NIR dose planning in the brain.

PubMed

Verleker, Akshay Prabhu; Shaffer, Michael; Fang, Qianqian; Choi, Mi-Ran; Clare, Susan; Stantz, Keith M

2016-12-01

A three-dimensional photon dosimetry in tissues is critical in designing optical therapeutic protocols to trigger light-activated drug release. The objective of this study is to investigate the feasibility of a Monte Carlo-based optical therapy planning software by developing dosimetry tools to characterize and cross-validate the local photon fluence in brain tissue, as part of a long-term strategy to quantify the effects of photoactivated drug release in brain tumors. An existing GPU-based 3D Monte Carlo (MC) code was modified to simulate near-infrared photon transport with differing laser beam profiles within phantoms of skull bone (B), white matter (WM), and gray matter (GM). A novel titanium-based optical dosimetry probe with isotropic acceptance was used to validate the local photon fluence, and an empirical model of photon transport was developed to significantly decrease execution time for clinical application. Comparisons between the MC and the dosimetry probe measurements were on an average 11.27%, 13.25%, and 11.81% along the illumination beam axis, and 9.4%, 12.06%, 8.91% perpendicular to the beam axis for WM, GM, and B phantoms, respectively. For a heterogeneous head phantom, the measured % errors were 17.71% and 18.04% along and perpendicular to beam axis. The empirical algorithm was validated by probe measurements and matched the MC results (R²0.99), with average % error of 10.1%, 45.2%, and 22.1% relative to probe measurements, and 22.6%, 35.8%, and 21.9% relative to the MC, for WM, GM, and B phantoms, respectively. The simulation time for the empirical model was 6 s versus 8 h for the GPU-based Monte Carlo for a head phantom simulation. These tools provide the capability to develop and optimize treatment plans for optimal release of pharmaceuticals in the treatment of cancer. Future work will test and validate these novel delivery and release mechanisms in vivo.

Thin film tritium dosimetry

DOEpatents

Moran, Paul R.

1976-01-01

The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

In vivo thermoluminescence dosimetry for total body irradiation.

PubMed

Palkosková, P; Hlavata, H; Dvorák, P; Novotný, J; Novotný, J

2002-01-01

An improvement in the clinical results obtained using total body irradiation (TBI) with photon beams requires precise TBI treatment planning, reproducible irradiation, precise in vivo dosimetry, accurate documentation and careful evaluation. In vivo dosimetry using LiF Harshaw TLD-100 chips was used during the TBI treatments performed in our department. The results of in vivo thermoluminescence dosimetry (TLD) show that using TLD measurements and interactive adjustment of some treatment parameters based on these measurements, like monitor unit calculations, lung shielding thickness and patient positioning, it is possible to achieve high precision in absorbed dose delivery (less than 0.5%) as well as in homogeneity of irradiation (less than 6%).

Characterization of the nanoDot OSLD dosimeter in CT.

PubMed

Scarboro, Sarah B; Cody, Dianna; Alvarez, Paola; Followill, David; Court, Laurence; Stingo, Francesco C; Zhang, Di; McNitt-Gray, Michael; Kry, Stephen F

2015-04-01

The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80-140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly effects due to changes in beam quality, could be more

Characterization of the nanoDot OSLD dosimeter in CT

PubMed Central

Scarboro, Sarah B.; Cody, Dianna; Alvarez, Paola; Followill, David; Court, Laurence; Stingo, Francesco C.; Zhang, Di; Kry, Stephen F.

2015-01-01

Purpose: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. Methods: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80–140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Results: Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Conclusions: Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly effects due

Characterization of the nanoDot OSLD dosimeter in CT

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

Scarboro, Sarah B.; Graduate School of Biomedical Sciences, The University of Texas Health Science Center Houston, Houston, Texas 77030; The Methodist Hospital, Houston, Texas 77030

Purpose: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. Methods: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dosemore » linearity, and angular dependence were characterized through direct measurement for CT energies (80–140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Results: Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Conclusions: Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly

EANM Dosimetry Committee series on standard operational procedures for pre-therapeutic dosimetry II. Dosimetry prior to radioiodine therapy of benign thyroid diseases.

PubMed

Hänscheid, Heribert; Canzi, Cristina; Eschner, Wolfgang; Flux, Glenn; Luster, Markus; Strigari, Lidia; Lassmann, Michael

2013-07-01

The EANM Dosimetry Committee Series "Standard Operational Procedures for Pre-Therapeutic Dosimetry" (SOP) provides advice to scientists and clinicians on how to perform patient-specific absorbed dose assessments. This particular SOP describes how to tailor the therapeutic activity to be administered for radioiodine therapy of benign thyroid diseases such as Graves' disease or hyperthyroidism. Pretherapeutic dosimetry is based on the assessment of the individual (131)I kinetics in the target tissue after the administration of a tracer activity. The present SOP makes proposals on the equipment to be used and guides the user through the measurements. Time schedules for the measurement of the fractional (131)I uptake in the diseased tissue are recommended and it is shown how to calculate from these datasets the therapeutic activity necessary to administer a predefined target dose in the subsequent therapy. Potential sources of error are pointed out and the inherent uncertainties of the procedures depending on the number of measurements are discussed. The theoretical background and the derivation of the listed equations from compartment models of the iodine kinetics are explained in a supplementary file published online only.

Topical Review: Polymer gel dosimetry

PubMed Central

Baldock, C; De Deene, Y; Doran, S; Ibbott, G; Jirasek, A; Lepage, M; McAuley, K B; Oldham, M; Schreiner, L J

2010-01-01

Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. PMID:20150687

Comparison of the NIST and ENEA Air Kerma Standards

PubMed Central

Laitano, R. F.; Lamperti, P. J.; Toni, M. P.

1998-01-01

A comparison was made between the National Institute of Standards and Technology (NIST) and Ente per le Nuove Tecnologie l’Energia e l’Ambiente (ENEA) air kerma standards for medium energy x rays and 60Co gamma rays. The comparison took place at ENEA in June 1994. Two different transfer chambers from NIST were used for the comparison. The measurements were made at radiation qualities similar to those used at the Bureau International des Poids et Mesures (BIPM) (generating voltages of 100 kV, 135 kV, 180 kV and 250 kV, respectively) and with 60Co gamma radiation. The transfer chamber calibration factors obtained at the NIST and at the ENEA agreed with one another to 0.03 % for 60Co gamma radiation and between 0.1 % to 0.8 % for the medium energy x-ray beam codes. PMID:28009356

Thermoluminescent dosimetry in veterinary diagnostic radiology.

PubMed

Hernández-Ruiz, L; Jimenez-Flores, Y; Rivera-Montalvo, T; Arias-Cisneros, L; Méndez-Aguilar, R E; Uribe-Izquierdo, P

2012-12-01

This paper presents the results of Environmental and Personnel Dosimetry made in a radiology area of a veterinary hospital. Dosimetry was realized using thermoluminescent (TL) materials. Environmental Dosimetry results show that areas closer to the X-ray equipment are safe. Personnel Dosimetry shows important measurements of daily workday in some persons near to the limit established by ICRP. TL results of radiation measurement suggest TLDs are good candidates as a dosimeter to radiation dosimetry in veterinary radiology. Copyright © 2012 Elsevier Ltd. All rights reserved.

Quantitative imaging for clinical dosimetry

NASA Astrophysics Data System (ADS)

Bardiès, Manuel; Flux, Glenn; Lassmann, Michael; Monsieurs, Myriam; Savolainen, Sauli; Strand, Sven-Erik

2006-12-01

Patient-specific dosimetry in nuclear medicine is now a legal requirement in many countries throughout the EU for targeted radionuclide therapy (TRT) applications. In order to achieve that goal, an increased level of accuracy in dosimetry procedures is needed. Current research in nuclear medicine dosimetry should not only aim at developing new methods to assess the delivered radiation absorbed dose at the patient level, but also to ensure that the proposed methods can be put into practice in a sufficient number of institutions. A unified dosimetry methodology is required for making clinical outcome comparisons possible.

Iron-based radiochromic systems for UV dosimetry applications

NASA Astrophysics Data System (ADS)

Lee, Hannah J.; Alqathami, Mamdooh; Blencowe, Anton; Ibbott, Geoffrey

2018-01-01

Phototherapy treatment using ultraviolet (UV) A and B light sources has long existed as a treatment option for various skin conditions. Quality control for phototherapy treatment recommended by the British Association of Dermatologists and British Photodermatology Group generally focused on instrumentation-based dosimetry measurements. The purpose of this study was to present an alternative, easily prepared dosimeter system for the measurement of UV dose and as a simple quality assurance technique for phototherapy treatments. Five different UVA-sensitive radiochromic dosimeter formulations were investigated and responded with a measurable and visible optical change both in solution and in gel form. Iron(III) reduction reaction formulations were found to be more sensitive to UVA compared to iron(II) oxidation formulations. One iron(III) reduction formulation was found to be especially promising due to its sensitivity to UVA dose, ease of production, and linear response up to a saturation point.

Using exposure prediction tools to link exposure and dosimetry for risk-based decisions: A case study with phthalates.

PubMed

Moreau, Marjory; Leonard, Jeremy; Phillips, Katherine A; Campbell, Jerry; Pendse, Salil N; Nicolas, Chantel; Phillips, Martin; Yoon, Miyoung; Tan, Yu-Mei; Smith, Sherrie; Pudukodu, Harish; Isaacs, Kristin; Clewell, Harvey

2017-10-01

A few different exposure prediction tools were evaluated for use in the new in vitro-based safety assessment paradigm using di-2-ethylhexyl phthalate (DEHP) and dibutyl phthalate (DnBP) as case compounds. Daily intake of each phthalate was estimated using both high-throughput (HT) prediction models such as the HT Stochastic Human Exposure and Dose Simulation model (SHEDS-HT) and the ExpoCast heuristic model and non-HT approaches based on chemical specific exposure estimations in the environment in conjunction with human exposure factors. Reverse dosimetry was performed using a published physiologically based pharmacokinetic (PBPK) model for phthalates and their metabolites to provide a comparison point. Daily intakes of DEHP and DnBP were estimated based on the urinary concentrations of their respective monoesters, mono-2-ethylhexyl phthalate (MEHP) and monobutyl phthalate (MnBP), reported in NHANES (2011-2012). The PBPK-reverse dosimetry estimated daily intakes at the 50th and 95th percentiles were 0.68 and 9.58 μg/kg/d and 0.089 and 0.68 μg/kg/d for DEHP and DnBP, respectively. For DEHP, the estimated median from PBPK-reverse dosimetry was about 3.6-fold higher than the ExpoCast estimate (0.68 and 0.18 μg/kg/d, respectively). For DnBP, the estimated median was similar to that predicted by ExpoCast (0.089 and 0.094 μg/kg/d, respectively). The SHEDS-HT prediction of DnBP intake from consumer product pathways alone was higher at 0.67 μg/kg/d. The PBPK-reverse dosimetry-estimated median intake of DEHP and DnBP was comparable to values previously reported for US populations. These comparisons provide insights into establishing criteria for selecting appropriate exposure prediction tools for use in an integrated modeling platform to link exposure to health effects. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Considerations for Developing a Dosimetry-Based Cumulative Risk Assessment Approach for Mixtures of Environmental Contaminants (Final Report)

EPA Science Inventory

EPA announced the availability of the final report, Considerations for Developing a Dosimetry-Based Cumulative Risk Assessment Approach for Mixtures of Environmental Contaminants. This report describes a process that can be used to determine the potential value of develop...

Reference dosimetry of proton pencil beams based on dose-area product: a proof of concept.

PubMed

Gomà, Carles; Safai, Sairos; Vörös, Sándor

2017-06-21

This paper describes a novel approach to the reference dosimetry of proton pencil beams based on dose-area product ([Formula: see text]). It depicts the calibration of a large-diameter plane-parallel ionization chamber in terms of dose-area product in a 60 Co beam, the Monte Carlo calculation of beam quality correction factors-in terms of dose-area product-in proton beams, the Monte Carlo calculation of nuclear halo correction factors, and the experimental determination of [Formula: see text] of a single proton pencil beam. This new approach to reference dosimetry proves to be feasible, as it yields [Formula: see text] values in agreement with the standard and well-established approach of determining the absorbed dose to water at the centre of a broad homogeneous field generated by the superposition of regularly-spaced proton pencil beams.

Reference natural radionuclide concentrations in Australian soils and derived terrestrial air kerma rate.

PubMed

Kleinschmidt, R

2017-06-01

Sediment from drainage catchment outlets has been shown to be a useful means of sampling large land masses for soil composition. Naturally occurring radioactive material concentrations (uranium, thorium and potassium-40) in soil have been collated and converted to activity concentrations using data collected from the National Geochemistry Survey of Australia. Average terrestrial air kerma rate data are derived using the elemental concentration data, and is tabulated for Australia and states for use as baseline reference information. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

EURADOS strategic research agenda: vision for dosimetry of ionising radiation

PubMed Central

Rühm, W.; Fantuzzi, E.; Harrison, R.; Schuhmacher, H.; Vanhavere, F.; Alves, J.; Bottollier Depois, J. F.; Fattibene, P.; Knežević, Ž.; Lopez, M. A.; Mayer, S.; Miljanić, S.; Neumaier, S.; Olko, P.; Stadtmann, H.; Tanner, R.; Woda, C.

2016-01-01

Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises—based on input from EURADOS Working Groups (WGs) and Voting Members—five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org). PMID:25752758

Important comments on KERMA factors and DPA cross-section data in ACE files of JENDL-4.0, JEFF-3.2 and ENDF/B-VII.1

NASA Astrophysics Data System (ADS)

Konno, Chikara; Tada, Kenichi; Kwon, Saerom; Ohta, Masayuki; Sato, Satoshi

2017-09-01

We have studied reasons of differences of KERMA factors and DPA cross-section data among nuclear data libraries. Here the KERMA factors and DPA cross-section data included in the official ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 are examined in more detail. As a result, it is newly found out that the KERMA factors and DPA cross-section data of a lot of nuclei are different among JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 and reasons of the differences are the followings: 1) large secondary particle production yield, 2) no secondary gamma data, 3) secondary gamma data in files12-15 mt = 3, 4) mt = 103-107 data without mt = 600 s-800 s data in file6. The issue 1) is considered to be due to nuclear data, while the issues 2)-4) seem to be due to NJOY. The ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 with these problems should be revised after correcting wrong nuclear data and NJOY problems.

Pin-photodiode array for the measurement of fan-beam energy and air kerma distributions of X-ray CT scanners.

PubMed

Haba, Tomonobu; Koyama, Shuji; Aoyama, Takahiko; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao; Kameyama, Hiroshi; Tsutsumi, Yoshinori

2016-07-01

Patient dose estimation in X-ray computed tomography (CT) is generally performed by Monte Carlo simulation of photon interactions within anthropomorphic or cylindrical phantoms. An accurate Monte Carlo simulation requires an understanding of the effects of the bow-tie filter equipped in a CT scanner, i.e. the change of X-ray energy and air kerma along the fan-beam arc of the CT scanner. To measure the effective energy and air kerma distributions, we devised a pin-photodiode array utilizing eight channels of X-ray sensors arranged at regular intervals along the fan-beam arc of the CT scanner. Each X-ray sensor consisted of two plate type of pin silicon photodiodes in tandem - front and rear photodiodes - and of a lead collimator, which only allowed X-rays to impinge vertically to the silicon surface of the photodiodes. The effective energy of the X-rays was calculated from the ratio of the output voltages of the photodiodes and the dose was calculated from the output voltage of the front photodiode using the energy and dose calibration curves respectively. The pin-photodiode array allowed the calculation of X-ray effective energies and relative doses, at eight points simultaneously along the fan-beam arc of a CT scanner during a single rotation of the scanner. The fan-beam energy and air kerma distributions of CT scanners can be effectively measured using this pin-photodiode array. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Comparison of the NIST and ENEA air kerma standards

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

Laitano, R.F.; Toni, M.P.; Lamperti, P.J.

1998-07-01

A comparison was made between the National Institute of Standards and Technology (NIST) and Ente per le Nuov Tecnologie l`Energia e l`Ambiente (ENEA) air kerma standards for medium energy x rays and {sup 60}Co gamma rays. The comparison took place at ENEA in June 1994. Two different transfer chambers from NIST were used for the comparison. The measurements were made at radiation qualities similar to those used at the Bureau International des Poids et Mesures (BIPM) (generating voltages of 100 kV, 135 kV, 180 kV and 250 kV, respectively) and with {sup 60}Co gamma radiation. The transfer chamber calibration factorsmore » obtained at the NIST and at the ENEA agreed with one another to 0.03% for {sup 60}Co gamma radiation and between 0.1% to 0.8% for the medium energy x-ray beam codes.« less

Characterising an aluminium oxide dosimetry system.

PubMed

Conheady, Clement F; Gagliardi, Frank M; Ackerly, Trevor

2015-09-01

In vivo dosimetry is recommended as a defence-in-depth strategy in radiotherapy treatments and is currently employed by clinics around the world. The characteristics of a new optically stimulated luminescence dosimetry system were investigated for the purpose of replacing an aging thermoluminescence dosimetry system for in vivo dosimetry. The stability of the system was not sufficient to satisfy commissioning requirements and therefore it has not been released into clinical service at this time.

Dosimetry for 131Cs and 125I seeds in solid water phantom using radiochromic EBT film.

PubMed

Chiu-Tsao, Sou-Tung; Napoli, John J; Davis, Stephen D; Hanley, Joseph; Rivard, Mark J

2014-09-01

To measure the 2D dose distributions with submillimeter resolution for (131)Cs (model CS-1 Rev2) and (125)I (model 6711) seeds in a Solid Water phantom using radiochromic EBT film for radial distances from 0.06cm to 5cm. To determine the TG-43 dosimetry parameters in water by applying Solid Water to liquid water correction factors generated from Monte Carlo simulations. Each film piece was positioned horizontally above and in close contact with a (131)Cs or (125)I seed oriented horizontally in a machined groove at the center of a Solid Water phantom, one film at a time. A total of 74 and 50 films were exposed to the (131)Cs and (125)I seeds, respectively. Different film sizes were utilized to gather data in different distance ranges. The exposure time varied according to the seed air-kerma strength and film size in order to deliver doses in the range covered by the film calibration curve. Small films were exposed for shorter times to assess the near field, while larger films were exposed for longer times in order to assess the far field. For calibration, films were exposed to either 40kV (M40) or 50kV (M50) x-rays in air at 100.0cm SSD with doses ranging from 0.2Gy to 40Gy. All experimental, calibration and background films were scanned at a 0.02cmpixel resolution using a CCD camera-based microdensitometer with a green light source. Data acquisition and scanner uniformity correction were achieved with Microd3 software. Data analysis was performed using ImageJ, FV, IDL and Excel software packages. 2D dose distributions were based on the calibration curve established for 50kV x-rays. The Solid Water to liquid water medium correction was calculated using the MCNP5 Monte Carlo code. Subsequently, the TG-43 dosimetry parameters in liquid water medium were determined. Values for the dose-rate constants using EBT film were 1.069±0.036 and 0.923±0.031cGyU(-1)h(-1) for (131)Cs and (125)I seed, respectively. The corresponding values determined using the Monte Carlo method

ESR dosimetry for atomic bomb survivors and radiologic technologists

NASA Astrophysics Data System (ADS)

Tatsumi-Miyajima, Junko

1987-06-01

An individual absorbed dose for atomic bomb (A-bomb) survivors and radiologic technologists has been estimated using a new personal dosimetry. This dosimetry is based on the electron spin resonance (ESR) spectroscopy of the CO 33- radicals, which are produced in their teeth by radiation. Measurements were carried out to study the characteristics of the dosimetry; the ESR signals of the CO 33- radicals were stable and increased linearly with the radiation dose. In the evaluation of the absorbed dose, the ESR signals were considered to be a function of photon energy. The absorbed doses in ten cases of A-bomb victims and eight cases of radiologic technologists were determined. For A-bomb survivors, the adsorbed doses, which were estimated using the ESR dosimetry, were consistent with the ones obtained using the calculations of the tissue dose in air of A-bomb, and also with the ones obtained using the chromosome measurements. For radiologic technologists, the absorbed doses, which were estimated using the ESR dosimetry, agreed with the ones calculated using the information on the occupational history and conditions. The advantages of this method are that the absorbed dose can be directly estimated by measuring the ESR signals obtained from the teeth of persons, who are exposed to radiation. Therefore, the ESR dosimetry is useful to estimate the accidental exposure and the long term cumulative dose.

Implicit dosimetry of microorganism photodynamic inactivation

NASA Astrophysics Data System (ADS)

Tamošiūnas, Mindaugas; Kuliešienė, Neringa; Daugelavičius, Rimantas

2017-12-01

Photosensitization based antibacterial treatment is efficient against a broad range of pathogens but it utilizes suboptimal dosimetry with an explicit (and very broad range) determination of sensitizer concentration, light dose and fluence rates. In this study we verified the implicit dosimetry approach for pathogen photodynamic treatment, employing protoporphyrin IX (ppIX) photobleaching to assess the killing efficacy against Staphylococcus aureus and Candida albicans cells. The results show that there was an increased kill of S. aureus and C. albicans at higher degree of ppIX fluorescence decay. Therefore ppIX photobleaching can be incorporated into the PDI dose metric offering to predict the pathogen killing efficacy during photodynamic treatment.

Current status of 3D EPID-based in vivo dosimetry in The Netherlands Cancer Institute

NASA Astrophysics Data System (ADS)

Mijnheer, B.; Olaciregui-Ruiz, I.; Rozendaal, R.; Spreeuw, H.; van Herk, M.; Mans, A.

2015-01-01

3D in vivo dose verification using a-Si EPIDs is performed routinely in our institution for almost all RT treatments. The EPID-based 3D dose distribution is reconstructed using a back-projection algorithm and compared with the planned dose distribution using 3D gamma evaluation. Dose-reconstruction and gamma-evaluation software runs automatically, and deviations outside the alert criteria are immediately available and investigated, in combination with inspection of cone-beam CT scans. The implementation of our 3D EPID- based in vivo dosimetry approach was able to replace pre-treatment verification for more than 90% of the patient treatments. Clinically relevant deviations could be detected for approximately 1 out of 300 patient treatments (IMRT and VMAT). Most of these errors were patient related anatomical changes or deviations from the routine clinical procedure, and would not have been detected by pre-treatment verification. Moreover, 3D EPID-based in vivo dose verification is a fast and accurate tool to assure the safe delivery of RT treatments. It provides clinically more useful information and is less time consuming than pre-treatment verification measurements. Automated 3D in vivo dosimetry is therefore a prerequisite for large-scale implementation of patient-specific quality assurance of RT treatments.

Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

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

Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr; Mavon, C.; Fromm, M.

2014-08-15

We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of airmore » kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.« less

EURADOS strategic research agenda: vision for dosimetry of ionising radiation.

PubMed

Rühm, W; Fantuzzi, E; Harrison, R; Schuhmacher, H; Vanhavere, F; Alves, J; Bottollier Depois, J F; Fattibene, P; Knežević, Ž; Lopez, M A; Mayer, S; Miljanić, S; Neumaier, S; Olko, P; Stadtmann, H; Tanner, R; Woda, C

2016-02-01

Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises-based on input from EURADOS Working Groups (WGs) and Voting Members-five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org). © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dosimetric characterization of two radium sources for retrospective dosimetry studies

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

Candela-Juan, C., E-mail: ccanjuan@gmail.com; Karlsson, M.; Lundell, M.

2015-05-15

Purpose: During the first part of the 20th century, {sup 226}Ra was the most used radionuclide for brachytherapy. Retrospective accurate dosimetry, coupled with patient follow up, is important for advancing knowledge on long-term radiation effects. The purpose of this work was to dosimetrically characterize two {sup 226}Ra sources, commonly used in Sweden during the first half of the 20th century, for retrospective dose–effect studies. Methods: An 8 mg {sup 226}Ra tube and a 10 mg {sup 226}Ra needle, used at Radiumhemmet (Karolinska University Hospital, Stockholm, Sweden), from 1925 to the 1960s, were modeled in two independent Monte Carlo (MC) radiationmore » transport codes: GEANT4 and MCNP5. Absorbed dose and collision kerma around the two sources were obtained, from which the TG-43 parameters were derived for the secular equilibrium state. Furthermore, results from this dosimetric formalism were compared with results from a MC simulation with a superficial mould constituted by five needles inside a glass casing, placed over a water phantom, trying to mimic a typical clinical setup. Calculated absorbed doses using the TG-43 formalism were also compared with previously reported measurements and calculations based on the Sievert integral. Finally, the dose rate at large distances from a {sup 226}Ra point-like-source placed in the center of 1 m radius water sphere was calculated with GEANT4. Results: TG-43 parameters [including g{sub L}(r), F(r, θ), Λ, and s{sub K}] have been uploaded in spreadsheets as additional material, and the fitting parameters of a mathematical curve that provides the dose rate between 10 and 60 cm from the source have been provided. Results from TG-43 formalism are consistent within the treatment volume with those of a MC simulation of a typical clinical scenario. Comparisons with reported measurements made with thermoluminescent dosimeters show differences up to 13% along the transverse axis of the radium needle. It has been

SU-E-T-284: Revisiting Reference Dosimetry for the Model S700 Axxent 50 KV{sub p} Electronic Brachytherapy Source

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

Hiatt, JR; Rivard, MJ

2014-06-01

Purpose: The model S700 Axxent electronic brachytherapy source by Xoft was characterized in 2006 by Rivard et al. The source design was modified in 2006 to include a plastic centering insert at the source tip to more accurately position the anode. The objectives of the current study were to establish an accurate Monte Carlo source model for simulation purposes, to dosimetrically characterize the new source and obtain its TG-43 brachytherapy dosimetry parameters, and to determine dose differences between the source with and without the centering insert. Methods: Design information from dissected sources and vendor-supplied CAD drawings were used to devisemore » the source model for radiation transport simulations of dose distributions in a water phantom. Collision kerma was estimated as a function of radial distance, r, and polar angle, θ, for determination of reference TG-43 dosimetry parameters. Simulations were run for 10{sup 10} histories, resulting in statistical uncertainties on the transverse plane of 0.03% at r=1 cm and 0.08% at r=10 cm. Results: The dose rate distribution the transverse plane did not change beyond 2% between the 2006 model and the current study. While differences exceeding 15% were observed near the source distal tip, these diminished to within 2% for r>1.5 cm. Differences exceeding a factor of two were observed near θ=150° and in contact with the source, but diminished to within 20% at r=10 cm. Conclusions: Changes in source design influenced the overall dose rate and distribution by more than 2% over a third of the available solid angle external from the source. For clinical applications using balloons or applicators with tissue located within 5 cm from the source, dose differences exceeding 2% were observed only for θ>110°. This study carefully examined the current source geometry and presents a modern reference TG-43 dosimetry dataset for the model S700 source.« less

EPR-dosimetry of ionizing radiation

NASA Astrophysics Data System (ADS)

Popova, Mariia; Vakhnin, Dmitrii; Tyshchenko, Igor

2017-09-01

This article discusses the problems that arise during the radiation sterilization of medical products. It is propose the solution based on alanine EPR-dosimetry. The parameters of spectrometer and methods of absorbed dose calculation are given. In addition, the problems that arise during heavy particles irradiation are investigated.

INTEGRATED OPERATIONAL DOSIMETRY SYSTEM AT CERN.

PubMed

Dumont, Gérald; Pedrosa, Fernando Baltasar Dos Santos; Carbonez, Pierre; Forkel-Wirth, Doris; Ninin, Pierre; Fuentes, Eloy Reguero; Roesler, Stefan; Vollaire, Joachim

2017-04-01

CERN, the European Organization for Nuclear Research, upgraded its operational dosimetry system in March 2013 to be prepared for the first Long Shutdown of CERN's facilities. The new system allows the immediate and automatic checking and recording of the dosimetry data before and after interventions in radiation areas. To facilitate the analysis of the data in context of CERN's approach to As Low As Reasonably Achievable (ALARA), this new system is interfaced to the Intervention Management Planning and Coordination Tool (IMPACT). IMPACT is a web-based application widely used in all CERN's accelerators and their associated technical infrastructures for the planning, the coordination and the approval of interventions (work permit principle). The coupling of the operational dosimetry database with the IMPACT repository allows a direct and almost immediate comparison of the actual dose with the estimations, in addition to enabling the configuration of alarm levels in the dosemeter in function of the intervention to be performed. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Direct measurement of air kerma rate in air from CDCS J-type caesium-137 therapy sources using a Farmer ionization chamber.

PubMed

Poynter, A J

2000-04-01

A simple method for directly measuring the reference air kerma rate from J-type 137Cs sources using a Farmer 2571 chamber has been evaluated. The method is useful as an independent means of verifying manufacturers' test data.

Reactor Dosimetry State of the Art 2008

NASA Astrophysics Data System (ADS)

Voorbraak, Wim; Debarberis, Luigi; D'Hondt, Pierre; Wagemans, Jan

2009-08-01

Oral session 1: Retrospective dosimetry. Retrospective dosimetry of VVER 440 reactor pressure vessel at the 3rd unit of Dukovany NPP / M. Marek ... [et al.]. Retrospective dosimetry study at the RPV of NPP Greifswald unit 1 / J. Konheiser ... [et al.]. Test of prototype detector for retrospective neutron dosimetry of reactor internals and vessel / K. Hayashi ... [et al.]. Neutron doses to the concrete vessel and tendons of a magnox reactor using retrospective dosimetry / D. A. Allen ... [et al.]. A retrospective dosimetry feasibility study for Atucha I / J. Wagemans ... [et al.]. Retrospective reactor dosimetry with zirconium alloy samples in a PWR / L. R. Greenwood and J. P. Foster -- Oral session 2: Experimental techniques. Characterizing the Time-dependent components of reactor n/y environments / P. J. Griffin, S. M. Luker and A. J. Suo-Anttila. Measurements of the recoil-ion response of silicon carbide detectors to fast neutrons / F. H. Ruddy, J. G. Seidel and F. Franceschini. Measurement of the neutron spectrum of the HB-4 cold source at the high flux isotope reactor at Oak Ridge National Laboratory / J. L. Robertson and E. B. Iverson. Feasibility of cavity ring-down laser spectroscopy for dose rate monitoring on nuclear reactor / H. Tomita ... [et al.]. Measuring transistor damage factors in a non-stable defect environment / D. B. King ... [et al.]. Neutron-detection based monitoring of void effects in boiling water reactors / J. Loberg ... [et al.] -- Poster session 1: Power reactor surveillance, retrospective dosimetry, benchmarks and inter-comparisons, adjustment methods, experimental techniques, transport calculations. Improved diagnostics for analysis of a reactor pulse radiation environment / S. M. Luker ... [et al.]. Simulation of the response of silicon carbide fast neutron detectors / F. Franceschini, F. H. Ruddy and B. Petrović. NSV A-3: a computer code for least-squares adjustment of neutron spectra and measured dosimeter responses / J. G

Personnel neutron dosimetry using electrochemically etched CR-39 foils

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

Hankins, D.E.; Homann, S.; Westermark, J.

1986-09-17

A personnel neutron dosimetry system has been developed based on the electrochemical etching of CR-39 plastic at elevated temperatures. The doses obtained using this dosimeter system are more accurate than those obtained using other dosimetry systems, especially when varied neutron spectra are encountered. This Cr-39 dosimetry system does not have the severe energy dependence that exists with albedo neutron dosimeters or the fading and reading problems encountered with NTA film. The dosimetry system employs an electrochemical etch procedure that be used to process large numbers of Cr-39 dosimeters. The etch procedure is suitable for operations where the number of personnelmore » requires that many CR-39 dosimeters be processed. Experience shows that one full-time technician can etch and evaluate 2000 foils per month. The energy response to neutrons is fairly flat from about 80 keV to 3.5 MeV, but drops by about a factor of three in the 13 to 16 MeV range. The sensitivity of the dosimetry system is about 7 tracks/cm/sup 2//mrem, with a background equivalent to about 8 mrem for new CR-39 foils. The limit of sensitivity is approximately 10 mrem. The dosimeter has a significant variation in directional dependence, dropping to about 20% at 90/sup 0/. This dosimeter has been used for personnel neutron dosimetry at the Lawrence Livermore National Laboratory for more tha 18 months. 6 refs., 23 figs., 2 tabs.« less

LWR pressure vessel surveillance dosimetry improvement program: LWR power reactor surveillance physics-dosimetry data base compendium

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

McElroy, W.N.

1985-08-01

This NRC physics-dosimetry compendium is a collation of information and data developed from available research and commercial light water reactor vessel surveillance program (RVSP) documents and related surveillance capsule reports. The data represents the results of the HEDL least-squares FERRET-SAND II Code re-evaluation of exposure units and values for 47 PWR and BWR surveillance capsules for W, B and W, CE, and GE power plants. Using a consistent set of auxiliary data and dosimetry-adjusted reactor physics results, the revised fluence values for E > 1 MeV averaged 25% higher than the originally reported values. The range of fluence values (new/old)more » was from a low of 0.80 to a high of 2.38. These HEDL-derived FERRET-SAND II exposure parameter values are being used for NRC-supported HEDL and other PWR and BWR trend curve data development and testing studies. These studies are providing results to support Revision 2 of Regulatory Guide 1.99. As stated by Randall (Ra84), the Guide is being updated to reflect recent studies of the physical basis for neutron radiation damage and efforts to correlate damage to chemical composition and fluence.« less

Primary Beam Air Kerma Dependence on Distance from Cargo and People Scanners.

PubMed

Strom, Daniel J; Cerra, Frank

2016-06-01

The distance dependence of air kerma or dose rate of the primary radiation beam is not obvious for security scanners of cargo and people in which there is relative motion between a collimated source and the person or object being imaged. To study this problem, one fixed line source and three moving-source scan-geometry cases are considered, each characterized by radiation emanating perpendicular to an axis. The cases are 1) a stationary line source of radioactive material, e.g., contaminated solution in a pipe; 2) a moving, uncollimated point source of radiation that is shuttered or off when it is stationary; 3) a moving, collimated point source of radiation that is shuttered or off when it is stationary; and 4) a translating, narrow "pencil" beam emanating in a flying-spot, raster pattern. Each case is considered for short and long distances compared to the line source length or path traversed by a moving source. The short distance model pertains mostly to dose to objects being scanned and personnel associated with the screening operation. The long distance model pertains mostly to potential dose to bystanders. For radionuclide sources, the number of nuclear transitions that occur a) per unit length of a line source or b) during the traversal of a point source is a unifying concept. The "universal source strength" of air kerma rate at 1 m from the source can be used to describe x-ray machine or radionuclide sources. For many cargo and people scanners with highly collimated fan or pencil beams, dose varies as the inverse of the distance from the source in the near field and with the inverse square of the distance beyond a critical radius. Ignoring the inverse square dependence and using inverse distance dependence is conservative in the sense of tending to overestimate dose.

Primary Beam Air Kerma Dependence on Distance from Cargo and People Scanners

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

Strom, Daniel J.; Cerra, Frank

The distance dependence of air kerma or dose rate of the primary radiation beam is not obvious for security scanners of cargo and people in which there is relative motion between a collimated source and the person or object being imaged. To study this problem, one fixed line source and three moving-source scan-geometry cases are considered, each characterized by radiation emanating perpendicular to an axis. The cases are 1) a stationary line source of radioactive material, e.g., contaminated solution in a pipe; 2) a moving, uncollimated point source of radiation that is shuttered or off when it is stationary; 3)more » a moving, collimated point source of radiation that is shuttered or off when it is stationary; and 4) a translating, narrow “pencil” beam emanating in a flying-spot, raster pattern. Each case is considered for short and long distances compared to the line source length or path traversed by a moving source. The short distance model pertains mostly to dose to objects being scanned and personnel associated with the screening operation. The long distance model pertains mostly to potential dose to bystanders. For radionuclide sources, the number of nuclear transitions that occur a) per unit length of a line source, or b) during the traversal of a point source, is a unifying concept. The “universal source strength” of air kerma rate at a meter from the source can be used to describe x-ray machine or radionuclide sources. For many cargo and people scanners with highly collimated fan or pencil beams, dose varies as the inverse of the distance from the source in the near field and with the inverse square of the distance beyond a critical radius. Ignoring the inverse square dependence and using inverse distance dependence is conservative in the sense of tending to overestimate dose.« less

MO-B-BRB-00: Three Dimensional Dosimetry

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

NONE

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

Modeling the impact of prostate edema on LDR brachytherapy: a Monte Carlo dosimetry study based on a 3D biphasic finite element biomechanical model

NASA Astrophysics Data System (ADS)

Mountris, K. A.; Bert, J.; Noailly, J.; Rodriguez Aguilera, A.; Valeri, A.; Pradier, O.; Schick, U.; Promayon, E.; Gonzalez Ballester, M. A.; Troccaz, J.; Visvikis, D.

2017-03-01

Prostate volume changes due to edema occurrence during transperineal permanent brachytherapy should be taken under consideration to ensure optimal dose delivery. Available edema models, based on prostate volume observations, face several limitations. Therefore, patient-specific models need to be developed to accurately account for the impact of edema. In this study we present a biomechanical model developed to reproduce edema resolution patterns documented in the literature. Using the biphasic mixture theory and finite element analysis, the proposed model takes into consideration the mechanical properties of the pubic area tissues in the evolution of prostate edema. The model’s computed deformations are incorporated in a Monte Carlo simulation to investigate their effect on post-operative dosimetry. The comparison of Day1 and Day30 dosimetry results demonstrates the capability of the proposed model for patient-specific dosimetry improvements, considering the edema dynamics. The proposed model shows excellent ability to reproduce previously described edema resolution patterns and was validated based on previous findings. According to our results, for a prostate volume increase of 10-20% the Day30 urethra D10 dose metric is higher by 4.2%-10.5% compared to the Day1 value. The introduction of the edema dynamics in Day30 dosimetry shows a significant global dose overestimation identified on the conventional static Day30 dosimetry. In conclusion, the proposed edema biomechanical model can improve the treatment planning of transperineal permanent brachytherapy accounting for post-implant dose alterations during the planning procedure.

Modeling the impact of prostate edema on LDR brachytherapy: a Monte Carlo dosimetry study based on a 3D biphasic finite element biomechanical model.

PubMed

Mountris, K A; Bert, J; Noailly, J; Aguilera, A Rodriguez; Valeri, A; Pradier, O; Schick, U; Promayon, E; Ballester, M A Gonzalez; Troccaz, J; Visvikis, D

2017-03-21

Prostate volume changes due to edema occurrence during transperineal permanent brachytherapy should be taken under consideration to ensure optimal dose delivery. Available edema models, based on prostate volume observations, face several limitations. Therefore, patient-specific models need to be developed to accurately account for the impact of edema. In this study we present a biomechanical model developed to reproduce edema resolution patterns documented in the literature. Using the biphasic mixture theory and finite element analysis, the proposed model takes into consideration the mechanical properties of the pubic area tissues in the evolution of prostate edema. The model's computed deformations are incorporated in a Monte Carlo simulation to investigate their effect on post-operative dosimetry. The comparison of Day1 and Day30 dosimetry results demonstrates the capability of the proposed model for patient-specific dosimetry improvements, considering the edema dynamics. The proposed model shows excellent ability to reproduce previously described edema resolution patterns and was validated based on previous findings. According to our results, for a prostate volume increase of 10-20% the Day30 urethra D10 dose metric is higher by 4.2%-10.5% compared to the Day1 value. The introduction of the edema dynamics in Day30 dosimetry shows a significant global dose overestimation identified on the conventional static Day30 dosimetry. In conclusion, the proposed edema biomechanical model can improve the treatment planning of transperineal permanent brachytherapy accounting for post-implant dose alterations during the planning procedure.

Relationship between student selection criteria and learner success for medical dosimetry students

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

Baker, Jamie, E-mail: jabaker@mdanderson.org; Tucker, Debra; Raynes, Edilberto

Medical dosimetry education occupies a specialized branch of allied health higher education. Noted international shortages of health care workers, reduced university funding, limitations on faculty staffing, trends in learner attrition, and increased enrollment of nontraditional students force medical dosimetry educational leadership to reevaluate current admission practices. Program officials wish to select medical dosimetry students with the best chances of successful graduation. The purpose of the quantitative ex post facto correlation study was to investigate the relationship between applicant characteristics (cumulative undergraduate grade point average (GPA), science grade point average (SGPA), prior experience as a radiation therapist, and previous academic degrees)more » and the successful completion of a medical dosimetry program, as measured by graduation. A key finding from the quantitative study was the statistically significant positive correlation between a student's previous degree and his or her successful graduation from the medical dosimetry program. Future research investigations could include a larger research sample, representative of more medical dosimetry student populations, and additional studies concerning the relationship of previous work as a radiation therapist and the effect on success as a medical dosimetry student. Based on the quantitative correlation analysis, medical dosimetry leadership on admissions committees could revise student selection rubrics to place less emphasis on an applicant's undergraduate cumulative GPA and increase the weight assigned to previous degrees.« less

Air-kerma strength determination of a new directional {sup 103}Pd source

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

Aima, Manik, E-mail: aima@wisc.edu; Reed, Joshua L.; DeWerd, Larry A.

2015-12-15

Purpose: A new directional {sup 103}Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing {sup 103}Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active {sup 103}Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normallymore » used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S{sub K}) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S{sub K} to a well-type ionization chamber. Methods: S{sub K} measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S{sub K} from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S{sub K} with the presence of gold fluorescent energy lines. In addition to S{sub K} measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S{sub K} values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to

Technical basis for external dosimetry at the Waste Isolation Pilot Plant (WIPP)

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

Bradley, E.W.; Wu, C.F.; Goff, T.E.

1993-12-31

The WIPP External Dosimetry Program, administered by Westinghouse Electric Corporation, Waste Isolation Division, for the US Department of Energy (DOE), provides external dosimetry support services for operations at the Waste Isolation Pilot Plant (WIPP) Site. These operations include the receipt, experimentation with, storage, and disposal of transuranic (TRU) wastes. This document describes the technical basis for the WIPP External Radiation Dosimetry Program. The purposes of this document are to: (1) provide assurance that the WIPP External Radiation Dosimetry Program is in compliance with all regulatory requirements, (2) provide assurance that the WIPP External Radiation Dosimetry Program is derived from amore » sound technical base, (3) serve as a technical reference for radiation protection personnel, and (4) aid in identifying and planning for future needs. The external radiation exposure fields are those that are documented in the WIPP Final Safety Analysis Report.« less

Monte Carol-Based Dosimetry of Beta-Emitters for Intravascular Brachytherapy

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

Choi, C.K.

2002-06-25

Monte Carlo simulations for radiation dosimetry and the experimental verifications of the simulations have been developed for the treatment geometry of intravascular brachytherapy, a form of radionuclide therapy for occluded coronary disease (restenosis). Monte Carlo code, MCNP4C, has been used to calculate the radiation dose from the encapsulated array of B-emitting seeds (Sr/Y-source train). Solid water phantoms have been fabricated to measure the dose on the radiochromic films that were exposed to the beta source train for both linear and curved coronary vessel geometries. While the dose difference for the 5-degree curved vessel at the prescription point of f+2.0 mmmore » is within the 10% guideline set by the AAPM, however, the difference increased dramatically to 16.85% for the 10-degree case which requires additional adjustment for the acceptable dosimetry planning. The experimental dose measurements agree well with the simulation results« less

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

NASA Technical Reports Server (NTRS)

Braby, L. A.

1981-01-01

The development of a rugged portable dosimetry system, based on microdosimetry techniques, which will measure dose and evaluate dose equivalent in a mixed radiation field is described. Progress in the desired dosimetry system can be divided into three distinct areas: development of the radiation detector, and electron system are presented. The mathematical techniques required are investigated.

Student Perceptions of an Online Medical Dosimetry Program

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

Lenards, Nishele, E-mail: lenards.nish@uwlax.ed

2011-07-01

The University of Wisconsin-La Crosse offers the first online medical dosimetry program in the nation. There is no data to research a program of this type. This research consisted of the evaluation of other distance education programs including health profession programs in addition to face-to-face medical dosimetry programs. There was a need to collect and analyze student perceptions of online learning in medical dosimetry. This research provided a guide for future implementation by other programs as well as validated the University of Wisconsin-La Crosse program. Methodology used consisted of an electronic survey sent to all previous and currently enrolled studentsmore » in the University of Wisconsin-La Crosse medical dosimetry program. The survey was both quantitative and qualitative in demonstrating attitudinal perceptions of students in the program. Quantitative data was collected and analyzed using a 5-point Likert scale. Qualitative data was gathered based on the open-ended responses and the identifying themes from the responses. The results demonstrated an overall satisfaction with this program, the instructor, and the online courses. Students felt a sense of belonging to the courses and the program. Considering that a majority of the students had never taken an online course previously, the students felt there were no technology issues. Future research should include an evaluation of board exam statistics for students enrolled in the online and face-to-face medical dosimetry programs.« less

AFRRI Neutron Dosimetry and Radiobiology Conference

DTIC Science & Technology

1988-11-09

Neutron Dosimetry and Radiobiology 8 - 9 November 1988 Sponsored by Defense Nuclear Agency ARMED FORCES RADIOBIOLOGY RESEARCH INSTITUTE...neutron radiation is less amenable to amelioration by chemical radioprotectants and more difficult to assess by means of physical dosimetry . These...neutron dosimetry and radiobiology we have witnessed in the past several years,could not have been possible without the sustained efforts of many

Revisiting photodynamic therapy dosimetry: reductionist & surrogate approaches to facilitate clinical success

NASA Astrophysics Data System (ADS)

Pogue, Brian W.; Elliott, Jonathan T.; Kanick, Stephen C.; Davis, Scott C.; Samkoe, Kimberley S.; Maytin, Edward V.; Pereira, Stephen P.; Hasan, Tayyaba

2016-04-01

Photodynamic therapy (PDT) can be a highly complex treatment, with many parameters influencing treatment efficacy. The extent to which dosimetry is used to monitor and standardize treatment delivery varies widely, ranging from measurement of a single surrogate marker to comprehensive approaches that aim to measure or estimate as many relevant parameters as possible. Today, most clinical PDT treatments are still administered with little more than application of a prescribed drug dose and timed light delivery, and thus the role of patient-specific dosimetry has not reached widespread clinical adoption. This disconnect is at least partly due to the inherent conflict between the need to measure and understand multiple parameters in vivo in order to optimize treatment, and the need for expedience in the clinic and in the regulatory and commercialization process. Thus, a methodical approach to selecting primary dosimetry metrics is required at each stage of translation of a treatment procedure, moving from complex measurements to understand PDT mechanisms in pre-clinical and early phase I trials, towards the identification and application of essential dose-limiting and/or surrogate measurements in phase II/III trials. If successful, identifying the essential and/or reliable surrogate dosimetry measurements should help facilitate increased adoption of clinical PDT. In this paper, examples of essential dosimetry points and surrogate dosimetry tools that may be implemented in phase II/III trials are discussed. For example, the treatment efficacy as limited by light penetration in interstitial PDT may be predicted by the amount of contrast uptake in CT, and so this could be utilized as a surrogate dosimetry measurement to prescribe light doses based upon pre-treatment contrast. Success of clinical ALA-based skin lesion treatment is predicted almost uniquely by the explicit or implicit measurements of photosensitizer and photobleaching, yet the individualization of treatment

SU-F-BRA-10: Fricke Dosimetry: Determination of the G-Value for Ir-192 Energy Based On the NRC Methodology

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

Salata, C; David, M; Rosado, P

Purpose: Use the methodology developed by the National Research Council Canada (NRC), for Fricke Dosimetry, to determine the G-value used at Ir-192 energies. Methods: In this study the Radiology Science Laboratory of Rio de Janeiro State University (LCR),based the G-value determination on the NRC method, using polyethylene bags. Briefly, this method consists of interpolating the G-values calculated for Co-60 and 250 kV x-rays for the average energy of Ir-192 (380 keV). As the Co-60 G-value is well described at literature, and associated with low uncertainties, it wasn’t measured in this present study. The G-values for 150 kV (Effective energy ofmore » 68 keV), 250 kV (Effective energy of 132 keV)and 300 kV(Effective energy of 159 keV)were calculated using the air kerma given by a calibrated ion chamber, and making it equivalent to the absorbed to the Fricke solution, using a Monte Carlo calculated factor for this conversion. Instead of interpolations, as described by the NRC, we displayed the G-values points in a graph, and used the line equation to determine the G- value for Ir-192 (380 keV). Results: The measured G-values were 1.436 ± 0.002 µmol/J for 150 kV, 1.472 ± 0.002 µmol/J for 250 kV, 1.497 ± 0.003 µmol/J for 300 kV. The used G-value for Co-60 (1.25 MeV) was 1,613 µmol/J. The R-square of the fitted regression line among those G-value points was 0.991. Using the line equation, the calculate G-value for 380 KeV was 1.542 µmol/J. Conclusion: The Result found for Ir-192 G-value is 3,1% different (lower) from the NRC value. But it agrees with previous literature results, using different methodologies to calculate this parameter. We will continue this experiment measuring the G-value for Co-60 in order to compare with the NRC method and better understand the reasons for the found differences.« less

A comparison of clinic based dosimeters based on silica optical fibre and plastic optical fibre for in vivo dosimetry

NASA Astrophysics Data System (ADS)

Chen, Lingxia; O'Keeffe, Sinead; Woulfe, Peter; Lewis, Elfed

2017-04-01

Four sensors based on silica optical fibre and plastic optical fibre for clinical in-vivo dosimetry have been fabricated and tested on site at Galway Clinic. The initial comparison results have been attained for the four sensors when they have been irradiated with beam energies of 6 MV and 15 MV at different dose rates using a modern clinical linear accelerator (Linac) as the radiation source. According to the experimental test results, the sensors based on silica optical fibre exhibit greater sensitivity to the incident radiation beam than the sensors based on plastic optical fibre when they are exposed to identical irradiation conditions. The output intensity from the sensor based on silica fibre is 5 times higher than the sensor based on plastic optical fibre.

Evaluation of Dosimetry Check software for IMRT patient-specific quality assurance.

PubMed

Narayanasamy, Ganesh; Zalman, Travis; Ha, Chul S; Papanikolaou, Niko; Stathakis, Sotirios

2015-05-08

The purpose of this study is to evaluate the use of the Dosimetry Check system for patient-specific IMRT QA. Typical QA methods measure the dose in an array dosimeter surrounded by homogenous medium for which the treatment plan has been recomputed. With the Dosimetry Check system, fluence measurements acquired on a portal dosimeter is applied to the patient's CT scans. Instead of making dose comparisons in a plane, Dosimetry Check system produces isodose lines and dose-volume histograms based on the planning CT images. By exporting the dose distribution from the treatment planning system into the Dosimetry Check system, one is able to make a direct comparison between the calculated dose and the planned dose. The versatility of the software is evaluated with respect to the two IMRT techniques - step and shoot and volumetric arc therapy. The system analyzed measurements made using EPID, PTW seven29, and IBA MatriXX, and an intercomparison study was performed. Plans from patients previously treated at our institution with treated anatomical site on brain, head & neck, liver, lung, and prostate were analyzed using Dosimetry Check system for any anatomical site dependence. We have recommendations and possible precautions that may be necessary to ensure proper QA with the Dosimetry Check system.

Medical personnel and patient dosimetry during coronary angiography and intervention

NASA Astrophysics Data System (ADS)

Efstathopoulos, Efstathios P.; Makrygiannis, Stamatis S.; Kottou, Sofia; Karvouni, Evangelia; Giazitzoglou, Eleftherios; Korovesis, Socrates; Tzanalaridou, Efthalia; Raptou, Panagiota D.; Katritsis, Demosthenes G.

2003-09-01

Percutaneous coronary interventions are associated with increased radiation exposure compared to most radiological examinations. This prospective study aimed at (1) measuring entrance doses for all in-room personnel, (2) performing an assessment of patient effective dose and intracoronary doses, (3) investigating the contribution of each projection to kerma-area product (KAP) and irradiation time, (4) comparing results with established DRL values in this clinical setting and (5) estimating the risk for fatal cancer to patients and operators. Measurements were performed during 40 consecutive procedures of coronary angiography (CA), half of which were followed by ad hoc coronary angioplasty (PTCA). KAP measurements were used for patients and thermoluminescent dosimetry for the in-room personnel. The mean KAP value per procedure for CA was 29 +/- 9 Gy cm2. Thirty four per cent of KAP was due to fluoroscopy, whereas the remainder (66%) was due to digital cine. Accordingly, the mean KAP value per PTCA procedure was 75 +/- 30 Gy cm2, and contribution of fluoroscopy is 57%. Effective dose per year was estimated to be 0.04-0.05 mSv y-1 for the primary operator, and 0.03-0.04 mSv y-1 for those assisting. Corresponding measurements for radiographer and nurse were below detectable level, implying minimal radiation hazards for them. Regarding radiation exposure, coronary intervention is considered a quite safe procedure for both patients and personnel in laboratories with modern equipment and experienced operators as long as standard safety precautions are considered. Exposure optimization though should be constantly sought through continuous review of procedures.

On the feasibility of comprehensive high-resolution 3D remote dosimetry

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

Juang, Titania; Grant, Ryan; Adamovics, John

2014-07-15

Purpose: This study investigates the feasibility of remote high-resolution 3D dosimetry with the PRESAGE®/Optical-CT system. In remote dosimetry, dosimeters are shipped out from a central base institution to a remote institution for irradiation, then shipped back to the base institution for subsequent readout and analysis. Methods: Two nominally identical optical-CT scanners for 3D dosimetry were constructed and placed at the base (Duke University) and remote (Radiological Physics Center) institutions. Two formulations of PRESAGE® (SS1, SS2) radiochromic dosimeters were investigated. Higher sensitivity was expected in SS1, which had higher initiator content (0.25% bromotrichloromethane), while greater temporal stability was expected in SS2.more » Four unirradiated PRESAGE® dosimeters (two per formulation, cylindrical dimensions 11 cm diameter, 8.5–9.5 cm length) were imaged at the base institution, then shipped to the remote institution for planning and irradiation. Each dosimeter was irradiated with the same simple treatment plan: an isocentric 3-field “cross” arrangement of 4 × 4 cm open 6 MV beams configured as parallel opposed laterals with an anterior beam. This simple plan was amenable to accurate and repeatable setup, as well as accurate dose modeling by a commissioned treatment planning system (Pinnacle). After irradiation and subsequent (within 1 h) optical-CT readout at the remote institution, the dosimeters were shipped back to the base institution for remote dosimetry readout 3 days postirradiation. Measured on-site and remote relative 3D dose distributions were registered to the Pinnacle dose calculation, which served as the reference distribution for 3D gamma calculations with passing criteria of 5%/2 mm, 3%/3 mm, and 3%/2 mm with a 10% dose threshold. Gamma passing rates, dose profiles, and color-maps were all used to assess and compare the performance of both PRESAGE® formulations for remote dosimetry. Results: The best agreements

Relationship between student selection criteria and learner success for medical dosimetry students.

PubMed

Baker, Jamie; Tucker, Debra; Raynes, Edilberto; Aitken, Florence; Allen, Pamela

2016-01-01

Medical dosimetry education occupies a specialized branch of allied health higher education. Noted international shortages of health care workers, reduced university funding, limitations on faculty staffing, trends in learner attrition, and increased enrollment of nontraditional students force medical dosimetry educational leadership to reevaluate current admission practices. Program officials wish to select medical dosimetry students with the best chances of successful graduation. The purpose of the quantitative ex post facto correlation study was to investigate the relationship between applicant characteristics (cumulative undergraduate grade point average (GPA), science grade point average (SGPA), prior experience as a radiation therapist, and previous academic degrees) and the successful completion of a medical dosimetry program, as measured by graduation. A key finding from the quantitative study was the statistically significant positive correlation between a student׳s previous degree and his or her successful graduation from the medical dosimetry program. Future research investigations could include a larger research sample, representative of more medical dosimetry student populations, and additional studies concerning the relationship of previous work as a radiation therapist and the effect on success as a medical dosimetry student. Based on the quantitative correlation analysis, medical dosimetry leadership on admissions committees could revise student selection rubrics to place less emphasis on an applicant׳s undergraduate cumulative GPA and increase the weight assigned to previous degrees. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

10 CFR 835.1304 - Nuclear accident dosimetry.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b) Nuclear...

10 CFR 835.1304 - Nuclear accident dosimetry.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b) Nuclear...

10 CFR 835.1304 - Nuclear accident dosimetry.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b) Nuclear...

10 CFR 835.1304 - Nuclear accident dosimetry.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b) Nuclear...

10 CFR 835.1304 - Nuclear accident dosimetry.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b) Nuclear...

Skin dosimetry of patients during interventional cardiology procedures in the Czech Republic

NASA Astrophysics Data System (ADS)

Sukupova, Lucie; Novak, Leos

2008-01-01

The aim of the study is to determine distribution of air kerma-area product, fluoro time and number of frames values for the two most frequent procedures in the interventional cardiology, to reconstruct skin dose distributions for some patients undergoing coronarography and percutaneous transluminal coronary angioplasty procedures. Patient dose data were obtained from X-ray unit dose monitoring software report from one hospital and the reconstructions were performed in MATLAB. Dependence of maximum skin dose on air kerma-area product, fluoro time and number of frames was determined to assess trigger levels of these quantities, which can indicate possible exceeding of the 2 Gy skin dose threshold.

TH-A-204-02: Part II - Worldwide Radiation Metrology

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

McEwen, M.

The ICRU is currently finalizing a report on key data for radiation dosimetry. This multi-year review has resulted in a number of recommendations regarding “fundamental” data that are used in dosimetry related to radiation therapy. This educational session will explain the background for the ICRU committee’s work, the content and conclusions of the report and the impact on outputs, including NIST primary standards, ADCL calibration coefficients and clinical reference dosimetry. Parameters and beam modalities potentially affected by this report include: The mean excitation energy, I, for graphite, air, and water, The average energy required to create an ion pair inmore » dry air (commonly referred to as W/e), The uncertainty in the determination of air kerma in kV x-rays The absolute value of Co-60 and Cs-137 primary standards and the dissemination of calibration coefficients, The determination of air kerma strength for Ir-192 HDR brachytherapy sources Ion chamber kQ factors for linac MV beams Ion chamber kQ factors for proton beams. The changes in reference dosimetry that would result from adoption of the ICRU recommendations are of the order of 0.5% to 1%, an effect that will not impact clinical dose delivery but will be detectable in the clinical setting. This session will also outline how worldwide metrology is coordinated through the Convention of the Meter and therefore how the international dosimetry community will proceed with adopting these recommendations so that uniformity from country to country in reference dosimetry is maintained. Timelines and communications methods will also be discussed to ensure that users, such as clinical medical physicists, are not surprised when their chamber’s calibration coefficient apparently changes. Learning Objectives: Understand the background for the ICRU committee’s work on key dosimetry data. Understand the proposed changes to key data and the impacts on reference dosimetry. Understand the methodology and

An Interlaboratory Comparison of Dosimetry for a Multi-institutional Radiobiological

PubMed Central

Seed, TM; Xiao, S; Manley, N; Nikolich-Zugich, J; Pugh, J; van den Brink, M; Hirabayashi, Y; Yasutomo, K; Iwama, A; Koyasu, S; Shterev, I; Sempowski, G; Macchiarini, F; Nakachi, K; Kunugi, KC; Hammer, CG; DeWerd, LA

2016-01-01

Purpose An interlaboratory comparison of radiation dosimetry was conducted to determine the accuracy of doses being used experimentally for animal exposures within a large multi-institutional research project. The background and approach to this effort are described and discussed in terms of basic findings, problems and solutions. Methods Dosimetry tests were carried out utilizing optically stimulated luminescence (OSL) dosimeters embedded midline into mouse carcasses and thermal luminescence dosimeters (TLD) embedded midline into acrylic phantoms. Results The effort demonstrated that the majority (4/7) of the laboratories was able to deliver sufficiently accurate exposures having maximum dosing errors of ≤ 5%. Comparable rates of ‘dosimetric compliance’ were noted between OSL- and TLD-based tests. Data analysis showed a highly linear relationship between ‘measured’ and ‘target’ doses, with errors falling largely between 0–20%. Outliers were most notable for OSL-based tests, while multiple tests by ‘non-compliant’ laboratories using orthovoltage x-rays contributed heavily to the wide variation in dosing errors. Conclusions For the dosimetrically non-compliant laboratories, the relatively high rates of dosing errors were problematic, potentially compromising the quality of ongoing radiobiological research. This dosimetry effort proved to be instructive in establishing rigorous reviews of basic dosimetry protocols ensuring that dosing errors were minimized. PMID:26857121

The Latin American Biological Dosimetry Network (LBDNet).

PubMed

García, O; Di Giorgio, M; Radl, A; Taja, M R; Sapienza, C E; Deminge, M M; Fernández Rearte, J; Stuck Oliveira, M; Valdivia, P; Lamadrid, A I; González, J E; Romero, I; Mandina, T; Guerrero-Carbajal, C; ArceoMaldonado, C; Cortina Ramírez, G E; Espinoza, M; Martínez-López, W; Di Tomasso, M

2016-09-01

Biological Dosimetry is a necessary support for national radiation protection programmes and emergency response schemes. The Latin American Biological Dosimetry Network (LBDNet) was formally founded in 2007 to provide early biological dosimetry assistance in case of radiation emergencies in the Latin American Region. Here are presented the main topics considered in the foundational document of the network, which comprise: mission, partners, concept of operation, including the mechanism to request support for biological dosimetry assistance in the region, and the network capabilities. The process for network activation and the role of the coordinating laboratory during biological dosimetry emergency response is also presented. This information is preceded by historical remarks on biological dosimetry cooperation in Latin America. A summary of the main experimental and practical results already obtained by the LBDNet is also included. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Partition Model-Based 99mTc-MAA SPECT/CT Predictive Dosimetry Compared with 90Y TOF PET/CT Posttreatment Dosimetry in Radioembolization of Hepatocellular Carcinoma: A Quantitative Agreement Comparison.

PubMed

Gnesin, Silvano; Canetti, Laurent; Adib, Salim; Cherbuin, Nicolas; Silva Monteiro, Marina; Bize, Pierre; Denys, Alban; Prior, John O; Baechler, Sebastien; Boubaker, Ariane

2016-11-01

90 Y-microsphere selective internal radiation therapy (SIRT) is a valuable treatment in unresectable hepatocellular carcinoma (HCC). Partition-model predictive dosimetry relies on differential tumor-to-nontumor perfusion evaluated on pretreatment 99m Tc-macroaggregated albumin (MAA) SPECT/CT. The aim of this study was to evaluate agreement between the predictive dosimetry of 99m Tc-MAA SPECT/CT and posttreatment dosimetry based on 90 Y time-of-flight (TOF) PET/CT. We compared the 99m Tc-MAA SPECT/CT results for 27 treatment sessions (25 HCC patients, 41 tumors) with 90 Y SIRT (7 glass spheres, 20 resin spheres) and the posttreatment 90 Y TOF PET/CT results. Three-dimensional voxelized dose maps were computed from the 99m Tc-MAA SPECT/CT and 90 Y TOF PET/CT data. Mean absorbed dose ([Formula: see text]) was evaluated to compute the predicted-to-actual dose ratio ([Formula: see text]) in tumor volumes (TVs) and nontumor volumes (NTVs) for glass and resin spheres. The Lin concordance ([Formula: see text]) was used to measure accuracy ([Formula: see text]) and precision (ρ). Administered activity ranged from 0.8 to 1.9 GBq for glass spheres and from 0.6 to 3.4 GBq for resin spheres, and the respective TVs ranged from 2 to 125 mL and from 6 to 1,828 mL. The mean dose [Formula: see text] was 240 Gy for glass and 122 Gy for resin in TVs and 72 Gy for glass and 47 Gy for resin in NTVs. [Formula: see text] was 1.46 ± 0.58 (0.65-2.53) for glass and 1.16 ± 0.41 (0.54-2.54) for resin, and the respective values for [Formula: see text] were 0.88 ± 0.15 (0.56-1.00) and 0.86 ± 0.2 (0.58-1.35). DR variability was substantially lower in NTVs than in TVs. The Lin concordance between [Formula: see text] and [Formula: see text] (resin) was significantly better for tumors larger than 150 mL than for tumors 150 mL or smaller ([Formula: see text] = 0.93 and [Formula: see text] = 0.95 vs. [Formula: see text] = 0.57 and [Formula: see text] = 0.93; P < 0.05). In 90 Y radioembolization

Internal dosimetry technical basis manual

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

Not Available

1990-12-20

The internal dosimetry program at the Savannah River Site (SRS) consists of radiation protection programs and activities used to detect and evaluate intakes of radioactive material by radiation workers. Examples of such programs are: air monitoring; surface contamination monitoring; personal contamination surveys; radiobioassay; and dose assessment. The objectives of the internal dosimetry program are to demonstrate that the workplace is under control and that workers are not being exposed to radioactive material, and to detect and assess inadvertent intakes in the workplace. The Savannah River Site Internal Dosimetry Technical Basis Manual (TBM) is intended to provide a technical and philosophicalmore » discussion of the radiobioassay and dose assessment aspects of the internal dosimetry program. Detailed information on air, surface, and personal contamination surveillance programs is not given in this manual except for how these programs interface with routine and special bioassay programs.« less

Dosimetry for Small and Nonstandard Fields

NASA Astrophysics Data System (ADS)

Junell, Stephanie L.

The proposed small and non-standard field dosimetry protocol from the joint International Atomic Energy Agency (IAEA) and American Association of Physicist in Medicine working group introduces new reference field conditions for ionization chamber based reference dosimetry. Absorbed dose beam quality conversion factors (kQ factors) corresponding to this formalism were determined for three different models of ionization chambers: a Farmer-type ionization chamber, a thimble ionization chamber, and a small volume ionization chamber. Beam quality correction factor measurements were made in a specially developed cylindrical polymethyl methacrylate (PMMA) phantom and a water phantom using thermoluminescent dosimeters (TLDs) and alanine dosimeters to determine dose to water. The TLD system for absorbed dose to water determination in high energy photon and electron beams was fully characterized as part of this dissertation. The behavior of the beam quality correction factor was observed as it transfers the calibration coefficient from the University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) 60Co reference beam to the small field calibration conditions of the small field formalism. TLD-determined beam quality correction factors for the calibration conditions investigated ranged from 0.97 to 1.30 and had associated standard deviations from 1% to 3%. The alanine-determined beam quality correction factors ranged from 0.996 to 1.293. Volume averaging effects were observed with the Farmer-type ionization chamber in the small static field conditions. The proposed small and non-standard field dosimetry protocols new composite-field reference condition demonstrated its potential to reduce or remove ionization chamber volume dependancies, but the measured beam quality correction factors were not equal to the standard CoP's kQ, indicating a change in beam quality in the small and non-standard field dosimetry protocols new composite-field reference condition

[Automatic Extraction and Analysis of Dosimetry Data in Radiotherapy Plans].

PubMed

Song, Wei; Zhao, Di; Lu, Hong; Zhang, Biyun; Ma, Jun; Yu, Dahai

To improve the efficiency and accuracy of extraction and analysis of dosimetry data in radiotherapy plans for a batch of patients. With the interface function provided in Matlab platform, a program was written to extract the dosimetry data exported from treatment planning system in DICOM RT format and exported the dose-volume data to an Excel file with the SPSS compatible format. This method was compared with manual operation for 14 gastric carcinoma patients to validate the efficiency and accuracy. The output Excel data were compatible with SPSS in format, the dosimetry data error for PTV dose interval of 90%-98%, PTV dose interval of 99%-106% and all OARs were -3.48E-5 ± 3.01E-5, -1.11E-3 ± 7.68E-4, -7.85E-5 ± 9.91E-5 respectively. Compared with manual operation, the time required was reduced from 5.3 h to 0.19 h and input error was reduced from 0.002 to 0. The automatic extraction of dosimetry data in DICOM RT format for batch patients, the SPSS compatible data exportation, quick analysis were achieved in this paper. The efficiency of clinical researches based on dosimetry data analysis of large number of patients will be improved with this methods.

Nuclear accident dosimetry intercomparison studies

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

Sims, C.S.

1989-09-01

Twenty-two nuclear accident dosimetry intercomparison studies utilizing the fast-pulse Health Physics Research Reactor at the Oak Ridge National Laboratory have been conducted since 1965. These studies have provided a total of 62 different organizations a forum for discussion of criticality accident dosimetry, an opportunity to test their neutron and gamma-ray dosimetry systems under a variety of simulated criticality accident conditions, and the experience of comparing results with reference dose values as well as with the measured results obtained by others making measurements under identical conditions. Sixty-nine nuclear accidents (27 with unmoderated neutron energy spectra and 42 with eight different shieldedmore » spectra) have been simulated in the studies. Neutron doses were in the 0.2-8.5 Gy range and gamma doses in the 0.1-2.0 Gy range. A total of 2,289 dose measurements (1,311 neutron, 978 gamma) were made during the intercomparisons. The primary methods of neutron dosimetry were activation foils, thermoluminescent dosimeters, and blood sodium activation. The main methods of gamma dose measurement were thermoluminescent dosimeters, radiophotoluminescent glass, and film. About 68% of the neutron measurements met the accuracy guidelines (+/- 25%) and about 52% of the gamma measurements met the accuracy criterion (+/- 20%) for accident dosimetry.« less

TLD assessment of mouse dosimetry during microCT imaging

PubMed Central

Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

2008-01-01

Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm3 CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0±5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0±6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0±4.0 mGy and 97.0±5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0±5.0 mGy. The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality. PMID:18841837

Sci—Fri PM: Topics — 01: A monte carlo model of a miniature low-energy x-ray tube using EGSnrc

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

Watson, P; Seuntjens, J

The INTRABEAM system (Carl Zeiss, Oberkochen, Germany) is a miniature x-ray generator for use in intraoperative radiotherapy and brachytherapy. The device accelerates electrons to up to 50 keV, which are then steered down an evacuated needle probe to strike a thin gold target. For accurate dosimetry of the INTRABEAM system, it is important that the photon spectrum be well understood. Measurements based on air-kerma are heavily impacted by photon spectra, particularly for low photon energies due to the large photoelectric contribution in air mass energy absorption coefficient. While low energy photons have little clinical significance at treatment depths, they maymore » have a large effect on air-kerma measurements. In this work, we have developed an EGSnrc-based monte carlo (MC) model of the Zeiss INTRABEAM system to study the source photon spectra and half-value layers (HVLs) of the bare probe and with various spherical applicators. HVLs were calculated using the analytical attenuation of air-kerma spectra. The calculated bare probe spectrum was compared with simulated and measured results taken from literature. Differences in the L-line energies of gold were found between the spectra predicted by EGSnrc and Geant4. This is due to M and N shell averaging during atomic transitions in EGSnrc. The calculated HVLs of the bare probe and spherical applicators are consistent with literature reported measured values.« less

Unexplained overexposures on physical dosimetry reported by biological dosimetry.

PubMed

Montoro, A; Almonacid, M; Villaescusa, J I; Verdu, G

2009-01-01

The Medical Service of the Radiation Protection Service from the University Hospital La Fe (Valencia, Spain), carries out medical examinations of the workers occupationally exposed to ionising radiation. The Biological Dosimetry Laboratory is developing its activity since 2001. Up to now, the activities have been focused in performing biological dosimetry studies of Interventionists workers from La Fe Hospital. Recently, the Laboratory has been authorized by the Health Authority in the Valencian Community. Unexplained overexposures of workers and patients are also studied. Workers suspected of being overexposed to ionising radiation were referred for investigation by cytogenetic analysis. Two of these were from Hospitals of the Valencian Community and one belonged to an uranium mine from Portugal. Hospital workers had a physical dose by thermoluminiscence dosimeters (TLD) that exceeded the established limit. The worker of the uranium mine received a dose from a lost source of Cesium 137 with an activity of 170 mCi. All three cases showed normal values after the hematological analysis. Finally, the aim of this study consist to determine whether the dose showed by the dosimeter is reliable or not. In the case of workers that wore dosimeter, it is concluded that the doses measured by dosimeter are not corresponding to real doses. Hospital worker with a physical dose of 2.6 Sv and 0.269 Sv had an estimated absorbed dose by biological dosimetry of 0.076 Gy (0-0.165 Gy) and 0 Gy (0-0.089 Gy), respectively. In case of the mine worker an estimated absorbed dose of 0.073 Gy (0-0.159 Gy) was obtained by biological dosimetry. In all cases we used the odds ratio to present the results due to a very low frequency of observed aberrations [1].

Quantitative evaluation of patient-specific quality assurance using online dosimetry system

NASA Astrophysics Data System (ADS)

Jung, Jae-Yong; Shin, Young-Ju; Sohn, Seung-Chang; Min, Jung-Whan; Kim, Yon-Lae; Kim, Dong-Su; Choe, Bo-Young; Suh, Tae-Suk

2018-01-01

In this study, we investigated the clinical performance of an online dosimetry system (Mobius FX system, MFX) by 1) dosimetric plan verification using gamma passing rates and dose volume metrics and 2) error-detection capability evaluation by deliberately introduced machine error. Eighteen volumetric modulated arc therapy (VMAT) plans were studied. To evaluate the clinical performance of the MFX, we used gamma analysis and dose volume histogram (DVH) analysis. In addition, to evaluate the error-detection capability, we used gamma analysis and DVH analysis utilizing three types of deliberately introduced errors (Type 1: gantry angle-independent multi-leaf collimator (MLC) error, Type 2: gantry angle-dependent MLC error, and Type 3: gantry angle error). A dosimetric verification comparison of physical dosimetry system (Delt4PT) and online dosimetry system (MFX), gamma passing rates of the two dosimetry systems showed very good agreement with treatment planning system (TPS) calculation. For the average dose difference between the TPS calculation and the MFX measurement, most of the dose metrics showed good agreement within a tolerance of 3%. For the error-detection comparison of Delta4PT and MFX, the gamma passing rates of the two dosimetry systems did not meet the 90% acceptance criterion with the magnitude of error exceeding 2 mm and 1.5 ◦, respectively, for error plans of Types 1, 2, and 3. For delivery with all error types, the average dose difference of PTV due to error magnitude showed good agreement between calculated TPS and measured MFX within 1%. Overall, the results of the online dosimetry system showed very good agreement with those of the physical dosimetry system. Our results suggest that a log file-based online dosimetry system is a very suitable verification tool for accurate and efficient clinical routines for patient-specific quality assurance (QA).

A broad-group cross-section library based on ENDF/B-VII.0 for fast neutron dosimetry Applications

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

Alpan, F.A.

2011-07-01

A new ENDF/B-VII.0-based coupled 44-neutron, 20-gamma-ray-group cross-section library was developed to investigate the latest evaluated nuclear data file (ENDF) ,in comparison to ENDF/B-VI.3 used in BUGLE-96, as well as to generate an objective-specific library. The objectives selected for this work consisted of dosimetry calculations for in-vessel and ex-vessel reactor locations, iron atom displacement calculations for reactor internals and pressure vessel, and {sup 58}Ni(n,{gamma}) calculation that is important for gas generation in the baffle plate. The new library was generated based on the contribution and point-wise cross-section-driven (CPXSD) methodology and was applied to one of the most widely used benchmarks, themore » Oak Ridge National Laboratory Pool Critical Assembly benchmark problem. In addition to the new library, BUGLE-96 and an ENDF/B-VII.0-based coupled 47-neutron, 20-gamma-ray-group cross-section library was generated and used with both SNLRML and IRDF dosimetry cross sections to compute reaction rates. All reaction rates computed by the multigroup libraries are within {+-} 20 % of measurement data and meet the U. S. Nuclear Regulatory Commission acceptance criterion for reactor vessel neutron exposure evaluations specified in Regulatory Guide 1.190. (authors)« less

Twenty new ISO standards on dosimetry for radiation processing

NASA Astrophysics Data System (ADS)

Farrar, H., IV

2000-03-01

Twenty standards on essentially all aspects of dosimetry for radiation processing were published as new ISO standards in December 1998. The standards are based on 20 standard practices and guides developed over the past 14 years by Subcommittee E10.01 of the American Society for Testing and Materials (ASTM). The transformation to ISO standards using the 'fast track' process under ISO Technical Committee 85 (ISO/TC85) commenced in 1995 and resulted in some overlap of technical information between three of the new standards and the existing ISO Standard 11137 Sterilization of health care products — Requirements for validation and routine control — Radiation sterilization. Although the technical information in these four standards was consistent, compromise wording in the scopes of the three new ISO standards to establish precedence for use were adopted. Two of the new ISO standards are specifically for food irradiation applications, but the majority apply to all forms of gamma, X-ray, and electron beam radiation processing, including dosimetry for sterilization of health care products and the radiation processing of fruit, vegetables, meats, spices, processed foods, plastics, inks, medical wastes, and paper. Most of the standards provide exact procedures for using individual dosimetry systems or for characterizing various types of irradiation facilities, but one covers the selection and calibration of dosimetry systems, and another covers the treatment of uncertainties using the new ISO Type A and Type B evaluations. Unfortunately, nine of the 20 standards just adopted by the ISO are not the most recent versions of these standards and are therefore already out of date. To help solve this problem, efforts are being made to develop procedures to coordinate the ASTM and ISO development and revision processes for these and future ASTM-originating dosimetry standards. In the meantime, an additional four dosimetry standards have recently been published by the ASTM but

Eye lens dosimetry in interventional cardiology: results of staff dose measurements and link to patient dose levels.

PubMed

Antic, V; Ciraj-Bjelac, O; Rehani, M; Aleksandric, S; Arandjic, D; Ostojic, M

2013-01-01

Workers involved in interventional cardiology procedures receive high eye lens dose if protection is not used. Currently, there is no suitable method for routine use for the measurement of eye dose. Since most angiography machines are equipped with suitable patient dosemeters, deriving factors linking staff eye doses to the patient doses can be helpful. In this study the patient kerma-area product, cumulative dose at an interventional reference point and eye dose in terms of Hp(3) of the cardiologists, nurses and radiographers for interventional cardiology procedures have been measured. Correlations between the patient dose and the staff eye dose were obtained. The mean eye dose was 121 µSv for the first operator, 33 µSv for the second operator/nurse and 12 µSv for radiographer. Normalised eye lens doses per unit kerma-area product were 0.94 µSv Gy⁻¹ cm⁻² for the first operator, 0.33 µSv Gy⁻¹ cm⁻² for the second operator/nurse and 0.16 µSv Gy⁻¹ cm⁻² for radiographers. Statistical analysis indicated that there is a weak but significant (p < 0.01) correlation between the eye dose and the kerma-area product for all three staff categories. These values are based on a local practice and may provide useful reference for other studies for validation and for wider utilisation in assessing the eye dose using patient dose values.

The work programme of EURADOS on internal and external dosimetry.

PubMed

Rühm, W; Bottollier-Depois, J F; Gilvin, P; Harrison, R; Knežević, Ž; Lopez, M A; Tanner, R; Vargas, A; Woda, C

2018-01-01

Since the early 1980s, the European Radiation Dosimetry Group (EURADOS) has been maintaining a network of institutions interested in the dosimetry of ionising radiation. As of 2017, this network includes more than 70 institutions (research centres, dosimetry services, university institutes, etc.), and the EURADOS database lists more than 500 scientists who contribute to the EURADOS mission, which is to promote research and technical development in dosimetry and its implementation into practice, and to contribute to harmonisation of dosimetry in Europe and its conformance with international practices. The EURADOS working programme is organised into eight working groups dealing with environmental, computational, internal, and retrospective dosimetry; dosimetry in medical imaging; dosimetry in radiotherapy; dosimetry in high-energy radiation fields; and harmonisation of individual monitoring. Results are published as freely available EURADOS reports and in the peer-reviewed scientific literature. Moreover, EURADOS organises winter schools and training courses on various aspects relevant for radiation dosimetry, and formulates the strategic research needs in dosimetry important for Europe. This paper gives an overview on the most important EURADOS activities. More details can be found at www.eurados.org .

Estimation of mean glandular dose for contrast enhanced digital mammography: factors for use with the UK, European and IAEA breast dosimetry protocols

NASA Astrophysics Data System (ADS)

Dance, D. R.; Young, K. C.

2014-05-01

The UK, European and IAEA protocols for breast dosimetry in mammography use tabulations of conversion factors, which relate measurements of incident air kerma to the mean glandular dose to the breast. To supplement the existing tabulations, a Monte Carlo computer program has been used to calculate conversion factors for the high-energy spectra used for contrast enhanced digital mammography. The calculations were made for the x-ray spectra from a tungsten target (tube voltage range 40-50 kV) filtered by 0.28, 0.30 and 0.32 mm of copper, and from molybdenum and rhodium targets (tube voltage range 40-49 kV), each filtered by 0.30 mm of copper. The g-factors for all of these spectra were plotted for each breast thickness as a function of half value layer (HVL) and were found to lie on smooth curves within 0.3%. These reflect the fact that the characteristic x-rays present in the spectra from molybdenum and rhodium are heavily filtered and all the spectra are essentially Bremsstrahlung. As a consequence, the s-factor previously used in the dosimetry protocols to adjust for different target/filter combinations can be taken as unity for all of the spectra considered. Tables of g-factors and c-factors are provided for breast thicknesses in the range 20-110 mm and HVLs in the range 2.4-3.6 mm of aluminium. The tables of c-factors are given for breast glandularities in the range 0.1%-100% and for typical glandularities for women in the age bands 40-49 and 50-64 attending the UK national breast screening programme.

Comparison for Air Kerma from Radiation Protection Gamma-ray Beams with Brazilian Network - 2016/2017

NASA Astrophysics Data System (ADS)

Cabral, TS; da Silva, CNM; Potiens, MPA; Soares, CMA; Silveira, RR; Khoury, H.; Saito, V.; Fernandes, E.; Cardoso, WF; de Oliveira, HPS; Pires, MA; de Amorim, AS; Balthar, M.

2018-03-01

The results of the comparison involving 9 laboratories in Brazil are reported. The measured quantity was the air kerma in 137Cs and 60Co, at the level of radioprotection. The comparison was conducted by the National Laboratory Metrology of Ionizing Radiation (LNMRI/IRD) from October 2016 to March 2017. The largest deviation between the calibration coefficients was 0.8% for 137Cs and 0.7% for 60Co. This proficiency exercise proved the technical capacity of the Brazilian calibration network in radiation monitors and the results were used by some in the implementation of the standard ISO/IEC 17025.

PREFACE: Third International Conference on Radiotherapy Gel Dosimetry

NASA Astrophysics Data System (ADS)

DeDeene, Yves; Baldock, Clive

2004-01-01

Gel dosimetry is not merely another dosimetry technique. Gel dosimeters are integrating dosimeters that enable dose verification in three dimensions. The application of a 3D dosimetry technique in the clinic would give a real push to the implementation of advanced high-precision radiotherapy technologies in many institutes. It can be expected that with the recent developments in the field towards more user-friendly gel systems and imaging modalities, gel dosimetry will become a vital link in the chain of high-precision radiation cancer therapy in the near future. Many researchers all over the world have contributed to the emerging technology of gel dosimetry. The research field of gel dosimetry is recognized to be very broad from polymer and analytical chemistry and material research to imaging technologies. The DOSGEL conferences in the past have proven to be an important forum at which material scientists, chemists, medical physicists, magnetic resonance imaging and radiation specialists brought together a critical mass of thoughts, findings and considerations. DOSGEL 2004 has been endorsed by many international, supra-national and national medical physics organizations and publishers. These proceedings contain 51 papers that cover various aspects of gel dosimetry.

Monte Carlo simulations in radiotherapy dosimetry.

PubMed

Andreo, Pedro

2018-06-27

The use of the Monte Carlo (MC) method in radiotherapy dosimetry has increased almost exponentially in the last decades. Its widespread use in the field has converted this computer simulation technique in a common tool for reference and treatment planning dosimetry calculations. This work reviews the different MC calculations made on dosimetric quantities, like stopping-power ratios and perturbation correction factors required for reference ionization chamber dosimetry, as well as the fully realistic MC simulations currently available on clinical accelerators, detectors and patient treatment planning. Issues are raised that include the necessity for consistency in the data throughout the entire dosimetry chain in reference dosimetry, and how Bragg-Gray theory breaks down for small photon fields. Both aspects are less critical for MC treatment planning applications, but there are important constraints like tissue characterization and its patient-to-patient variability, which together with the conversion between dose-to-water and dose-to-tissue, are analysed in detail. Although these constraints are common to all methods and algorithms used in different types of treatment planning systems, they make uncertainties involved in MC treatment planning to still remain "uncertain".

Response of LiF:Mg,Ti thermoluminescent dosimeters at photon energies relevant to the dosimetry of brachytherapy (<1 MeV)

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

Tedgren, Aasa Carlsson; Hedman, Angelica; Grindborg, Jan-Erik

2011-10-15

Purpose: High energy photon beams are used in calibrating dosimeters for use in brachytherapy since absorbed dose to water can be determined accurately and with traceability to primary standards in such beams, using calibrated ion chambers and standard dosimetry protocols. For use in brachytherapy, beam quality correction factors are needed, which include corrections for differences in mass energy absorption properties between water and detector as well as variations in detector response (intrinsic efficiency) with radiation quality, caused by variations in the density of ionization (linear energy transfer (LET) -distributions) along the secondary electron tracks. The aim of this work wasmore » to investigate experimentally the detector response of LiF:Mg,Ti thermoluminescent dosimeters (TLD) for photon energies below 1 MeV relative to {sup 60}Co and to address discrepancies between the results found in recent publications of detector response. Methods: LiF:Mg,Ti dosimeters of formulation MTS-N Poland were irradiated to known values of air kerma free-in-air in x-ray beams at tube voltages 25-250 kV, in {sup 137}Cs- and {sup 60}Co-beams at the Swedish Secondary Standards Dosimetry Laboratory. Conversions from air kerma free-in-air into values of mean absorbed dose in the dosimeters in the actual irradiation geometries were made using EGSnrc Monte Carlo simulations. X-ray energy spectra were measured or calculated for the actual beams. Detector response relative to that for {sup 60}Co was determined at each beam quality. Results: An increase in relative response was seen for all beam qualities ranging from 8% at tube voltage 25 kV (effective energy 13 keV) to 3%-4% at 250 kV (122 keV effective energy) and {sup 137}Cs with a minimum at 80 keV effective energy (tube voltage 180 kV). The variation with effective energy was similar to that reported by Davis et al.[Radiat. Prot. Dosim. 106, 33-43 (2003)] with our values being systematically lower by 2%-4%. Compared to

Response of LiF:Mg,Ti thermoluminescent dosimeters at photon energies relevant to the dosimetry of brachytherapy (<1 MeV).

PubMed

Tedgren, Asa Carlsson; Hedman, Angelica; Grindborg, Jan-Erik; Carlsson, Gudrun Alm

2011-10-01

High energy photon beams are used in calibrating dosimeters for use in brachytherapy since absorbed dose to water can be determined accurately and with traceability to primary standards in such beams, using calibrated ion chambers and standard dosimetry protocols. For use in brachytherapy, beam quality correction factors are needed, which include corrections for differences in mass energy absorption properties between water and detector as well as variations in detector response (intrinsic efficiency) with radiation quality, caused by variations in the density of ionization (linear energy transfer (LET) -distributions) along the secondary electron tracks. The aim of this work was to investigate experimentally the detector response of LiF:Mg,Ti thermoluminescent dosimeters (TLD) for photon energies below 1 MeV relative to (60)Co and to address discrepancies between the results found in recent publications of detector response. LiF:Mg,Ti dosimeters of formulation MTS-N Poland were irradiated to known values of air kerma free-in-air in x-ray beams at tube voltages 25-250 kV, in (137)Cs- and (60)Co-beams at the Swedish Secondary Standards Dosimetry Laboratory. Conversions from air kerma free-in-air into values of mean absorbed dose in the dosimeters in the actual irradiation geometries were made using EGSnrc Monte Carlo simulations. X-ray energy spectra were measured or calculated for the actual beams. Detector response relative to that for (60)Co was determined at each beam quality. An increase in relative response was seen for all beam qualities ranging from 8% at tube voltage 25 kV (effective energy 13 keV) to 3%-4% at 250 kV (122 keV effective energy) and (137)Cs with a minimum at 80 keV effective energy (tube voltage 180 kV). The variation with effective energy was similar to that reported by Davis et al. [Radiat. Prot. Dosim. 106, 33-43 (2003)] with our values being systematically lower by 2%-4%. Compared to the results by Nunn et al. [Med. Phys. 35, 1861

Skeletal dosimetry models for alpha-particles for use in molecular radiotherapy

NASA Astrophysics Data System (ADS)

Watchman, Christopher J.

Molecular radiotherapy is a cancer treatment methodology whereby a radionuclide is combined with a biologically active molecule to preferentially target cancer cells. Alpha-particle emitting radionuclides show significant potential for use in molecular radiotherapy due to the short range of the alpha-particles in tissue and their high rates of energy deposition. Current radiation dosimetry models used to assess alpha emitter dose in the skeleton were developed originally for occupational applications. In medical dosimetry, individual variability in uptake, translocation and other biological factors can result in poor correlation of clinical outcome with marrow dose estimates determined using existing skeletal models. Methods presented in this work were developed in response to the need for dosimetry models which account for these biological and patient-specific factors. Dosimetry models are presented for trabecular bone alpha particle dosimetry as well as a model for cortical bone dosimetry. These radiation transport models are the 3D chord-based infinite spongiosa transport model (3D-CBIST) and the chord-based infinite cortical transport model (CBICT), respectively. Absorbed fraction data for several skeletal tissues for several subjects are presented. Each modeling strategy accounts for biological parameters, such as bone marrow cellularity, not previously incorporated into alpha-particle skeletal dosimetry models used in radiation protection. Using these data a study investigating the variability in alpha-particle absorbed fractions in the human skeleton is also presented. Data is also offered relating skeletal tissue masses in individual bone sites for a range of ages. These data are necessary for dose calculations and have previously only been available as whole body tissue masses. A revised 3D-CBIST model is also presented which allows for changes in endosteum thickness to account for revised target cell location of tissues involved in the radiological

Predicting lung dosimetry of inhaled particleborne benzo[a]pyrene using physiologically based pharmacokinetic modeling

PubMed Central

Campbell, Jerry; Franzen, Allison; Van Landingham, Cynthia; Lumpkin, Michael; Crowell, Susan; Meredith, Clive; Loccisano, Anne; Gentry, Robinan; Clewell, Harvey

2016-01-01

Abstract Benzo[a]pyrene (BaP) is a by-product of incomplete combustion of fossil fuels and plant/wood products, including tobacco. A physiologically based pharmacokinetic (PBPK) model for BaP for the rat was extended to simulate inhalation exposures to BaP in rats and humans including particle deposition and dissolution of absorbed BaP and renal elimination of 3-hydroxy benzo[a]pyrene (3-OH BaP) in humans. The clearance of particle-associated BaP from lung based on existing data in rats and dogs suggest that the process is bi-phasic. An initial rapid clearance was represented by BaP released from particles followed by a slower first-order clearance that follows particle kinetics. Parameter values for BaP-particle dissociation were estimated using inhalation data from isolated/ventilated/perfused rat lungs and optimized in the extended inhalation model using available rat data. Simulations of acute inhalation exposures in rats identified specific data needs including systemic elimination of BaP metabolites, diffusion-limited transfer rates of BaP from lung tissue to blood and the quantitative role of macrophage-mediated and ciliated clearance mechanisms. The updated BaP model provides very good prediction of the urinary 3-OH BaP concentrations and the relative difference between measured 3-OH BaP in nonsmokers versus smokers. This PBPK model for inhaled BaP is a preliminary tool for quantifying lung BaP dosimetry in rat and humans and was used to prioritize data needs that would provide significant model refinement and robust internal dosimetry capabilities. PMID:27569524

A method to improve the effectiveness of diode in vivo dosimetry.

PubMed

Alecu, R; Alecu, M; Ochran, T G

1998-05-01

A routine diode in vivo dosimetry program based on a combination of entrance and exit dose measurements was clinically implemented in the radiation oncology department of Grace Hospital, Detroit, in January 1995. The delivered dose has been monitored by taking weekly measurements. The calibration of the diodes and the in vivo dosimetry protocol for this new, more effective type of dose verification is presented. The problems encountered within the program are discussed along with our solutions.

Collision-kerma conversion between dose-to-tissue and dose-to-water by photon energy-fluence corrections in low-energy brachytherapy.

PubMed

Giménez-Alventosa, Vicent; Antunes, Paula C G; Vijande, Javier; Ballester, Facundo; Pérez-Calatayud, José; Andreo, Pedro

2017-01-07

The AAPM TG-43 brachytherapy dosimetry formalism, introduced in 1995, has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations, except in the vicinity of the source capsule. Subsequent dosimetry developments, based on Monte Carlo calculations or analytical solutions of transport equations, do not rely on the CPE assumption and determine directly the dose to different tissues. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seeds is proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences. State-of-the art Monte Carlo calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone), which in all cases include a realistic modelling of low-energy brachytherapy sources in order to benchmark the formalism proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases (e.g. bone tissue).

Collision-kerma conversion between dose-to-tissue and dose-to-water by photon energy-fluence corrections in low-energy brachytherapy

NASA Astrophysics Data System (ADS)

Giménez-Alventosa, Vicent; Antunes, Paula C. G.; Vijande, Javier; Ballester, Facundo; Pérez-Calatayud, José; Andreo, Pedro

2017-01-01

The AAPM TG-43 brachytherapy dosimetry formalism, introduced in 1995, has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations, except in the vicinity of the source capsule. Subsequent dosimetry developments, based on Monte Carlo calculations or analytical solutions of transport equations, do not rely on the CPE assumption and determine directly the dose to different tissues. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seeds is proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences. State-of-the art Monte Carlo calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone), which in all cases include a realistic modelling of low-energy brachytherapy sources in order to benchmark the formalism proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases (e.g. bone tissue).

Implementation of alanine/EPR as transfer dosimetry system in a radiotherapy audit programme in Belgium.

PubMed

Schaeken, B; Cuypers, R; Lelie, S; Schroeyers, W; Schreurs, S; Janssens, H; Verellen, D

2011-04-01

A measurement procedure based on alanine/electron paramagnetic resonance (EPR) dosimetry was implemented successfully providing simple, stable, and accurate dose-to-water (D(w)) measurements. The correspondence between alanine and ionization chamber measurements in reference conditions was excellent. Alanine/EMR dosimetry might be a valuable alternative to thermoluminescent (TLD) and ionization chamber based measuring procedures in radiotherapy audits. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

WE-AB-204-11: Development of a Nuclear Medicine Dosimetry Module for the GPU-Based Monte Carlo Code ARCHER

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

Liu, T; Lin, H; Xu, X

Purpose: To develop a nuclear medicine dosimetry module for the GPU-based Monte Carlo code ARCHER. Methods: We have developed a nuclear medicine dosimetry module for the fast Monte Carlo code ARCHER. The coupled electron-photon Monte Carlo transport kernel included in ARCHER is built upon the Dose Planning Method code (DPM). The developed module manages the radioactive decay simulation by consecutively tracking several types of radiation on a per disintegration basis using the statistical sampling method. Optimization techniques such as persistent threads and prefetching are studied and implemented. The developed module is verified against the VIDA code, which is based onmore » Geant4 toolkit and has previously been verified against OLINDA/EXM. A voxelized geometry is used in the preliminary test: a sphere made of ICRP soft tissue is surrounded by a box filled with water. Uniform activity distribution of I-131 is assumed in the sphere. Results: The self-absorption dose factors (mGy/MBqs) of the sphere with varying diameters are calculated by ARCHER and VIDA respectively. ARCHER’s result is in agreement with VIDA’s that are obtained from a previous publication. VIDA takes hours of CPU time to finish the computation, while it takes ARCHER 4.31 seconds for the 12.4-cm uniform activity sphere case. For a fairer CPU-GPU comparison, more effort will be made to eliminate the algorithmic differences. Conclusion: The coupled electron-photon Monte Carlo code ARCHER has been extended to radioactive decay simulation for nuclear medicine dosimetry. The developed code exhibits good performance in our preliminary test. The GPU-based Monte Carlo code is developed with grant support from the National Institute of Biomedical Imaging and Bioengineering through an R01 grant (R01EB015478)« less

An automated voxelized dosimetry tool for radionuclide therapy based on serial quantitative SPECT/CT imaging

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

Jackson, Price A.; Kron, Tomas; Beauregard, Jean-Mathieu

2013-11-15

Purpose: To create an accurate map of the distribution of radiation dose deposition in healthy and target tissues during radionuclide therapy.Methods: Serial quantitative SPECT/CT images were acquired at 4, 24, and 72 h for 28 {sup 177}Lu-octreotate peptide receptor radionuclide therapy (PRRT) administrations in 17 patients with advanced neuroendocrine tumors. Deformable image registration was combined with an in-house programming algorithm to interpolate pharmacokinetic uptake and clearance at a voxel level. The resultant cumulated activity image series are comprised of values representing the total number of decays within each voxel's volume. For PRRT, cumulated activity was translated to absorbed dose basedmore » on Monte Carlo-determined voxel S-values at a combination of long and short ranges. These dosimetric image sets were compared for mean radiation absorbed dose to at-risk organs using a conventional MIRD protocol (OLINDA 1.1).Results: Absorbed dose values to solid organs (liver, kidneys, and spleen) were within 10% using both techniques. Dose estimates to marrow were greater using the voxelized protocol, attributed to the software incorporating crossfire effect from nearby tumor volumes.Conclusions: The technique presented offers an efficient, automated tool for PRRT dosimetry based on serial post-therapy imaging. Following retrospective analysis, this method of high-resolution dosimetry may allow physicians to prescribe activity based on required dose to tumor volume or radiation limits to healthy tissue in individual patients.« less

SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation

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

Welch, M; Jaffray, D; Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON

Purpose: Technological advances have revolutionized preclinical radiation research to enable precise radiation delivery in preclinical models. Kilovoltage x-rays and complex geometries in preclinical radiation studies challenge conventional dosimetry methods. Previously developed gel-based dosimetry provides a viable means of accommodating complex geometries and accurately reporting dose at kV energies. This paper will describe the development and evaluation of gel-based ferrous xylenol-orange (FXG) dosimetry using a 7T preclinical imaging system. Methods: To confirm water equivalence, Zeff values were calculated for the FXG material, water and ICRU defined soft tissue. Proton T1 relaxivity response in FXG was measured using a preclinical 7T MRmore » and a small animal irradiator for a dose range of 1–22 Gy. FXG was contained in 50 ml centrifuge tubes and irradiated with a 225 kVp x-ray beam at a nominal dose rate of 2.3 Gy/min. Pre and post irradiation maps of the T1 relaxivity were collected using variable TR spin-echo imaging (TE 6.65 ms; TR 500, 750, 1000, 1500, 2000, 3000 and 5000 ms) with 2 mm thick slices, 0.325 mm/pixel, 3 averages and an acquisition time of 26 minutes. A linear fit to the change in relaxation rate (1/T1) for the delivered doses reported the gel sensitivity in units of ms{sup -1}Gy{sup -1}. Irradiation and imaging studies were repeated using three batches of gel over 72 hrs. Results: FXG has a Zeff of 3.8 for the 225 kVp spectrum used; differing from water and ICRU defined soft tissue by 0.5% and 2.5%, respectively. The average sensitivity for the FXG dosimeter was 31.5 ± 0.7 ms{sup -1}Gy{sup -1} (R{sup 2} = 0.9957) with a y-intercept of −29.4 ± 9.0 ms{sup -1}. Conclusion: Preliminary results for the FXG dosimeter properties, sensitivity, and dose linearity at preclinical energies is promising. Future work will explore anatomically relevant tissue inclusions to test MR performance. Student funding provided by The Terry Fox

Probabilistic Reverse dOsimetry Estimating Exposure Distribution (PROcEED)

EPA Pesticide Factsheets

PROcEED is a web-based application used to conduct probabilistic reverse dosimetry calculations.The tool is used for estimating a distribution of exposure concentrations likely to have produced biomarker concentrations measured in a population.

Hanford internal dosimetry program manual

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

Carbaugh, E.H.; Sula, M.J.; Bihl, D.E.

1989-10-01

This document describes the Hanford Internal Dosimetry program. Program Services include administrating the bioassay monitoring program, evaluating and documenting assessments of internal exposure and dose, ensuring that analytical laboratories conform to requirements, selecting and applying appropriate models and procedures for evaluating internal radionuclide deposition and the resulting dose, and technically guiding and supporting Hanford contractors in matters regarding internal dosimetry. 13 refs., 16 figs., 42 tabs.

Development of a portable graphite calorimeter for radiation dosimetry.

PubMed

Sakama, Makoto; Kanai, Tatsuaki; Fukumura, Akifumi

2008-01-01

We developed and performance-tested a portable graphite calorimeter designed to measure the absolute dosimetry of various beams including heavy-ion beams, based on a flexible and convenient means of measurement. This measurement system is fully remote-controlled by the GPIB system. This system uses a digital PID (Proportional, Integral, Derivative) control method based on the LabVIEW software. It was possible to attain stable conditions in a shorter time by this system. The standard deviation of the measurements using the calorimeter was 0.79% at a dose rate of 0.8 Gy/min in 17 calorimeter runs for a (60)Co photon beam. The overall uncertainties for the absorbed dose to graphite and water of the (60)Co photon beam using the developed calorimeter were 0.89% and 1.35%, respectively. Estimations of the correction factors due to vacuum gaps, impurities in the core, the dose gradient and the radiation profile were included in the uncertainties. The absorbed doses to graphite and water irradiated by the (60)Co photon beam were compared with dosimetry measurements obtained using three ionization chambers. The absorbed doses to graphite and water estimated by the two dosimetry methods agreed within 0.1% and 0.3%, respectively.

Real-time dosimetry in radiotherapy using tailored optical fibers

NASA Astrophysics Data System (ADS)

Rahman, A. K. M. Mizanur; Zubair, H. T.; Begum, Mahfuza; Abdul-Rashid, H. A.; Yusoff, Z.; Omar, Nasr Y. M.; Ung, N. M.; Mat-Sharif, K. A.; Bradley, D. A.

2016-05-01

Real-time dosimetry plays an important role for accurate patient-dose measurement during radiotherapy. A tiny piece of laboratory fabricated Ge-doped optical fiber has been investigated as a radioluminescence (RL) sensor for real-time dosimetry over the dose range from 1 Gy to 8 Gy under 6 MV photon beam by LINAC. Fiber-coupled software-based RL prototype system was used to assess essential dosimetric characteristics including dose response linearity, dose rate dependency, sensitivity, repeatability and output dependence on field sizes. The consistency level of RL photon counts versus dose rate was also compared with that of standard Al2O3:C chips. Sensitivity of Ge-doped fiber were found to be sufficiently sensitive for practical use and also provided linear dose responses for various dose rates from 100 cGy/min to 600 cGy/min using both 6 MV photon and 6 MeV electron beams. SEM-EDX analysis was performed to identify Ge-dopant concentration level within the optical fiber RL material. Accumulated doses were also estimated using simple integral technique and the error was found to be around less than 1% under dissimilar dose rates or repeat measurements. The evaluation of the Ge-doped optical fiber based RL dosimeter system indicates its potential in medical dosimetry.

SU-E-J-214: MR Protocol Development to Visualize Sirius MRI Markers in Prostate Brachytherapy Patients for MR-Based Post-Implant Dosimetry

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

Lim, T; Wang, J; Frank, S

Purpose: The current CT-based post-implant dosimetry allows precise seed localization but limited anatomical delineation. Switching to MR-based post-implant dosimetry is confounded by imprecise seed localization. One approach is to place positive-contrast markers (Sirius) adjacent to the negative-contrast seeds. This patient study aims to assess the utility of a 3D fast spoiled gradient-recalled echo (FSPGR) sequence to visualize Sirius markers for post-implant dosimetry. Methods: MRI images were acquired in prostate implant patients (n=10) on Day 0 (day-of-implant) and Day 30. The post-implant MR protocol consisted of 3D T2-weighted fast-spin-echo (FSE), T2-weighted 2D-FSE (axial) and T1-weighted 2D-FSE (axial/sagittal/coronal). We incorporated a 3D-FSPGRmore » sequence into the post-implant MR protocol to visualize the Sirius markers. Patients were scanned with different number-of-excitations (6, 8, 10), field-of-view (10cm, 14cm, 18cm), slice thickness (1mm, 0.8mm), flip angle (14 degrees, 20 degrees), bandwidth (122.070 Hz/pixel, 325.508 Hz/pixel, 390.625 Hz/pixel), phase encoding steps (160, 192, 224, 256), frequency-encoding direction (right/left, anterior/posterior), echo-time type (minimum-full, out-of-phase), field strength (1.5T, 3T), contrast (with, without), scanner vendor (Siemens, GE), coil (endorectal-coil only, endorectal-and-torso-coil, torsocoil only), endorectal-coil filling (30cc, 50cc) and endorectal-coil filling type (air, perfluorocarbon [PFC]). For post-implant dosimetric evaluation with greater anatomical detail, 3D-FSE images were fused with 3D-FSPGR images. For comparison with CT-based post-implant dosimetry, CT images were fused with 3D-FSPGR images. Results: The 3D-FSPGR sequence facilitated visualization of markers in patients. Marker visualization helped distinguish signal voids as seeds versus needle tracks for more definitive MR-based post-implant dosimetry. On the CT-MR fused images, the distance between the seed on CT to MR

Edema and Seed Displacements Affect Intraoperative Permanent Prostate Brachytherapy Dosimetry

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

Westendorp, Hendrik, E-mail: r.westendorp@radiotherapiegroep.nl; Nuver, Tonnis T.; Department of Radiation Oncology, Radiotherapiegroep Behandellocatie Deventer, Deventer

Purpose: We sought to identify the intraoperative displacement patterns of seeds and to evaluate the correlation of intraoperative dosimetry with day 30 for permanent prostate brachytherapy. Methods and Materials: We analyzed the data from 699 patients. Intraoperative dosimetry was acquired using transrectal ultrasonography (TRUS) and C-arm cone beam computed tomography (CBCT). Intraoperative dosimetry (minimal dose to 40%-95% of the volume [D{sub 40}-D{sub 95}]) was compared with the day 30 dosimetry for both modalities. An additional edema-compensating comparison was performed for D{sub 90}. Stranded seeds were linked between TRUS and CBCT using an automatic and fast linking procedure. Displacement patterns weremore » analyzed for each seed implantation location. Results: On average, an intraoperative (TRUS to CBCT) D{sub 90} decline of 10.6% ± 7.4% was observed. Intraoperative CBCT D{sub 90} showed a greater correlation (R{sup 2} = 0.33) with respect to Day 30 than did TRUS (R{sup 2} = 0.17). Compensating for edema, the correlation increased to 0.41 for CBCT and 0.38 for TRUS. The mean absolute intraoperative seed displacement was 3.9 ± 2.0 mm. The largest seed displacements were observed near the rectal wall. The central and posterior seeds showed less caudal displacement than lateral and anterior seeds. Seeds that were implanted closer to the base showed more divergence than seeds close to the apex. Conclusions: Intraoperative CBCT D{sub 90} showed a greater correlation with the day 30 dosimetry than intraoperative TRUS. Edema seemed to cause most of the systematic difference between the intraoperative and day 30 dosimetry. Seeds near the rectal wall showed the most displacement, comparing TRUS and CBCT, probably because of TRUS probe–induced prostate deformation.« less

SU-E-T-552: Monte Carlo Calculation of Correction Factors for a Free-Air Ionization Chamber in Support of a National Air-Kerma Standard for Electronic Brachytherapy

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

Mille, M; Bergstrom, P

2015-06-15

Purpose: To use Monte Carlo radiation transport methods to calculate correction factors for a free-air ionization chamber in support of a national air-kerma standard for low-energy, miniature x-ray sources used for electronic brachytherapy (eBx). Methods: The NIST is establishing a calibration service for well-type ionization chambers used to characterize the strength of eBx sources prior to clinical use. The calibration approach involves establishing the well-chamber’s response to an eBx source whose air-kerma rate at a 50 cm distance is determined through a primary measurement performed using the Lamperti free-air ionization chamber. However, the free-air chamber measurements of charge or currentmore » can only be related to the reference air-kerma standard after applying several corrections, some of which are best determined via Monte Carlo simulation. To this end, a detailed geometric model of the Lamperti chamber was developed in the EGSnrc code based on the engineering drawings of the instrument. The egs-fac user code in EGSnrc was then used to calculate energy-dependent correction factors which account for missing or undesired ionization arising from effects such as: (1) attenuation and scatter of the x-rays in air; (2) primary electrons escaping the charge collection region; (3) lack of charged particle equilibrium; (4) atomic fluorescence and bremsstrahlung radiation. Results: Energy-dependent correction factors were calculated assuming a monoenergetic point source with the photon energy ranging from 2 keV to 60 keV in 2 keV increments. Sufficient photon histories were simulated so that the Monte Carlo statistical uncertainty of the correction factors was less than 0.01%. The correction factors for a specific eBx source will be determined by integrating these tabulated results over its measured x-ray spectrum. Conclusion: The correction factors calculated in this work are important for establishing a national standard for eBx which will help ensure

The Importance of Dosimetry Standardization in Radiobiology

PubMed Central

Desrosiers, Marc; DeWerd, Larry; Deye, James; Lindsay, Patricia; Murphy, Mark K; Mitch, Michael; Macchiarini, Francesca; Stojadinovic, Strahinja; Stone, Helen

2013-01-01

Radiation dose is central to much of radiobiological research. Precision and accuracy of dose measurements and reporting of the measurement details should be sufficient to allow the work to be interpreted and repeated and to allow valid comparisons to be made, both in the same laboratory and by other laboratories. Despite this, a careful reading of published manuscripts suggests that measurement and reporting of radiation dosimetry and setup for radiobiology research is frequently inadequate, thus undermining the reliability and reproducibility of the findings. To address these problems and propose a course of action, the National Cancer Institute (NCI), the National Institute of Allergy and Infectious Diseases (NIAID), and the National Institute of Standards and Technology (NIST) brought together representatives of the radiobiology and radiation physics communities in a workshop in September, 2011. The workshop participants arrived at a number of specific recommendations as enumerated in this paper and they expressed the desirability of creating dosimetry standard operating procedures (SOPs) for cell culture and for small and large animal experiments. It was also felt that these SOPs would be most useful if they are made widely available through mechanism(s) such as the web, where they can provide guidance to both radiobiologists and radiation physicists, be cited in publications, and be updated as the field and needs evolve. Other broad areas covered were the need for continuing education through tutorials at national conferences, and for journals to establish standards for reporting dosimetry. This workshop did not address issues of dosimetry for studies involving radiation focused at the sub-cellular level, internally-administered radionuclides, biodosimetry based on biological markers of radiation exposure, or dose reconstruction for epidemiological studies. PMID:26401441

WE-E-BRE-01: An Image-Based Skeletal Dosimetry Model for the ICRP Reference Adult Female - Internal Electron Sources

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

O'Reilly, S; Maynard, M; Marshall, E

Purpose: Limitations seen in previous skeletal dosimetry models, which are still employed in commonly used software today, include the lack of consideration of electron escape and cross-fire from cortical bone, the modeling of infinite spongiosa, the disregard of the effect of varying cellularity on active marrow self-irradiation, and the lack of use of the more recent ICRP definition of a 50 micron surrogate tissue region for the osteoprogenitor cells - shallow marrow. These limitations were addressed in the present dosimetry model. Methods: Electron transport was completed to determine specific absorbed fractions to active marrow and shallow marrow of the skeletalmore » regions of the adult female. The bone macrostructure was obtained from the whole-body hybrid computational phantom of the UF series of reference phantoms, while the bone microstructure was derived from microCT images of skeletal region samples taken from a 45 year-old female cadaver. The target tissue regions were active marrow and shallow marrow. The source tissues were active marrow, inactive marrow, trabecular bone volume, trabecular bone surfaces, cortical bone volume and cortical bone surfaces. The marrow cellularity was varied from 10 to 100 percent for active marrow self-irradiation. A total of 33 discrete electron energies, ranging from 1 keV to 10 MeV, were either simulated or modeled analytically. Results: The method of combining macro- and microstructure absorbed fractions calculated using MCNPX electron transport was found to yield results similar to those determined with the PIRT model for the UF adult male in the Hough et al. study. Conclusion: The calculated skeletal averaged absorbed fractions for each source-target combination were found to follow similar trends of more recent dosimetry models (image-based models) and did not follow current models used in nuclear medicine dosimetry at high energies (due to that models use of an infinite expanse of trabecular spongiosa)« less

Sixth international radiopharmaceutical dosimetry symposium: Proceedings. Volume 2

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

S.-Stelson, A.T.; Stabin, M.G.; Sparks, R.B.

1999-01-01

This conference was held May 7--10 in Gatlinburg, Tennessee. The purpose of this conference was to provide a multidisciplinary forum for exchange of state-of-the-art information on radiopharmaceutical dosimetry. Attention is focused on the following: quantitative analysis and treatment planning; cellular and small-scale dosimetry; dosimetric models; radiopharmaceutical kinetics and dosimetry; and animal models, extrapolation, and uncertainty.

Determination of the Kwall correction factor for a cylindrical ionization chamber to measure air-kerma in 60Co gamma beams.

PubMed

Laitano, R F; Toni, M P; Pimpinella, M; Bovi, M

2002-07-21

The factor Kwall to correct for photon attenuation and scatter in the wall of ionization chambers for 60Co air-kerma measurement has been traditionally determined by a procedure based on a linear extrapolation of the chamber current to zero wall thickness. Monte Carlo calculations by Rogers and Bielajew (1990 Phys. Med. Biol. 35 1065-78) provided evidence, mostly for chambers of cylindrical and spherical geometry, of appreciable deviations between the calculated values of Kwall and those obtained by the traditional extrapolation procedure. In the present work an experimental method other than the traditional extrapolation procedure was used to determine the Kwall factor. In this method the dependence of the ionization current in a cylindrical chamber was analysed as a function of an effective wall thickness in place of the physical (radial) wall thickness traditionally considered in this type of measurement. To this end the chamber wall was ideally divided into distinct regions and for each region an effective thickness to which the chamber current correlates was determined. A Monte Carlo calculation of attenuation and scatter effects in the different regions of the chamber wall was also made to compare calculation to measurement results. The Kwall values experimentally determined in this work agree within 0.2% with the Monte Carlo calculation. The agreement between these independent methods and the appreciable deviation (up to about 1%) between the results of both these methods and those obtained by the traditional extrapolation procedure support the conclusion that the two independent methods providing comparable results are correct and the traditional extrapolation procedure is likely to be wrong. The numerical results of the present study refer to a cylindrical cavity chamber like that adopted as the Italian national air-kerma standard at INMRI-ENEA (Italy). The method used in this study applies, however, to any other chamber of the same type.

Dose verification of eye plaque brachytherapy using spectroscopic dosimetry.

PubMed

Jarema, T; Cutajar, D; Weaver, M; Petasecca, M; Lerch, M; Kejda, A; Rosenfeld, A

2016-09-01

Eye plaque brachytherapy has been developed and refined for the last 80 years, demonstrating effective results in the treatment of ocular malignancies. Current dosimetry techniques for eye plaque brachytherapy (such as TLD- and film-based techniques) are time consuming and cannot be used prior to treatment in a sterile environment. The measurement of the expected dose distribution within the eye, prior to insertion within the clinical setting, would be advantageous, as any errors in source loading will lead to an erroneous dose distribution and inferior treatment outcomes. This study investigated the use of spectroscopic dosimetry techniques for real-time quality assurance of I-125 based eye plaques, immediately prior to insertion. A silicon detector based probe, operating in spectroscopy mode was constructed, containing a small (1 mm(3)) silicon detector, mounted within a ceramic holder, all encapsulated within a rubber sheath to prevent water infiltration of the electronics. Preliminary tests of the prototype demonstrated that the depth dose distribution through the central axis of an I-125 based eye plaque may be determined from AAPM Task Group 43 recommendations to a deviation of 6 % at 3 mm depth, 7 % at 5 mm depth, 1 % at 10 mm depth and 13 % at 20 mm depth, with the deviations attributed to the construction of the probe. A new probe design aims to reduce these discrepancies, however the concept of spectroscopic dosimetry shows great promise for use in eye plaque quality assurance in the clinical setting.

Key comparison BIPM.RI(I)-K5 of the air kerma standards of the ININ, Mexico and the BIPM in 137Cs gamma radiation

NASA Astrophysics Data System (ADS)

Kessler, C.; Burns, D. T.; Alvarez Romero, J. T.; De la Cruz Hernández, D.; Cabrera Vertti, M. R.; Tovar-Muñoz, V. M.

2015-01-01

A direct comparison of the standards for air kerma of the Instituto Nacional de Investigaciones Nucleares (ININ), Mexico, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in February 2015. The comparison result, evaluated as a ratio of the ININ and the BIPM standards for air kerma, is 1.0048 with a combined standard uncertainty of 2.0 × 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).

3D dosimetry by optical-CT scanning

NASA Astrophysics Data System (ADS)

Oldham, Mark

2006-12-01

The need for an accurate, practical, low-cost 3D dosimetry system is becoming ever more critical as modern dose delivery techniques increase in complexity and sophistication. A recent report from the Radiological Physics Center (RPC) (1), revealed that 38% of institutions failed the head-and-neck IMRT phantom credentialing test at the first attempt. This was despite generous passing criteria (within 7% dose-difference or 4mm distance-to-agreement) evaluated at a half-dozen points and a single axial plane. The question that arises from this disturbing finding is - what percentage of institutions would have failed if a comprehensive 3D measurement had been feasible, rather than measurements restricted to the central film-plane and TLD points? This question can only be adequately answered by a comprehensive 3D-dosimetry system, which presents a compelling argument for its development as a clinically viable low cost dosimetry solution. Optical-CT dosimetry is perhaps the closest system to providing such a comprehensive solution. In this article, we review the origins and recent developments of optical-CT dosimetry systems. The principle focus is on first generation systems known to have highest accuracy but longer scan times.

Automatic neutron dosimetry system based on fluorescent nuclear track detector technology.

PubMed

Akselrod, M S; Fomenko, V V; Bartz, J A; Haslett, T L

2014-10-01

For the first time, the authors are describing an automatic fluorescent nuclear track detector (FNTD) reader for neutron dosimetry. FNTD is a luminescent integrating type of detector made of aluminium oxide crystals that does not require electronics or batteries during irradiation. Non-destructive optical readout of the detector is performed using a confocal laser scanning fluorescence imaging with near-diffraction limited resolution. The fully automatic table-top reader allows one to load up to 216 detectors on a tray, read their engraved IDs using a CCD camera and optical character recognition, scan and process simultaneously two types of images in fluorescent and reflected laser light contrast to eliminate false-positive tracks related to surface and volume crystal imperfections. The FNTD dosimetry system allows one to measure neutron doses from 0.1 mSv to 20 Sv and covers neutron energies from thermal to 20 MeV. The reader is characterised by a robust, compact optical design, fast data processing electronics and user-friendly software. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A dual two dimensional electronic portal imaging device transit dosimetry model based on an empirical quadratic formalism

PubMed Central

Metwaly, M; Glegg, M; Baggarley, S P; Elliott, A

2015-01-01

Objective: This study describes a two dimensional electronic portal imaging device (EPID) transit dosimetry model that can predict either: (1) in-phantom exit dose, or (2) EPID transit dose, for treatment verification. Methods: The model was based on a quadratic equation that relates the reduction in intensity to the equivalent path length (EPL) of the attenuator. In this study, two sets of quadratic equation coefficients were derived from calibration dose planes measured with EPID and ionization chamber in water under reference conditions. With two sets of coefficients, EPL can be calculated from either EPID or treatment planning system (TPS) dose planes. Consequently, either the in-phantom exit dose or the EPID transit dose can be predicted from the EPL. The model was tested with two open, five wedge and seven sliding window prostate and head and neck intensity-modulated radiation therapy (IMRT) fields on phantoms. Results were analysed using absolute gamma analysis (3%/3 mm). Results: The open fields gamma pass rates were >96.8% for all comparisons. For wedge and IMRT fields, comparisons between predicted and TPS-computed in-phantom exit dose resulted in mean gamma pass rate of 97.4% (range, 92.3–100%). As for the comparisons between predicted and measured EPID transit dose, the mean gamma pass rate was 97.5% (range, 92.6–100%). Conclusion: An EPID transit dosimetry model that can predict in-phantom exit dose and EPID transit dose was described and proven to be valid. Advances in knowledge: The described model is practical, generic and flexible to encourage widespread implementation of EPID dosimetry for the improvement of patients' safety in radiotherapy. PMID:25969867

Tumor and red bone marrow dosimetry: comparison of methods for prospective treatment planning in pretargeted radioimmunotherapy.

PubMed

Woliner-van der Weg, Wietske; Schoffelen, Rafke; Hobbs, Robert F; Gotthardt, Martin; Goldenberg, David M; Sharkey, Robert M; Slump, Cornelis H; van der Graaf, Winette Ta; Oyen, Wim Jg; Boerman, Otto C; Sgouros, George; Visser, Eric P

2015-12-01

Red bone marrow (RBM) toxicity is dose-limiting in (pretargeted) radioimmunotherapy (RIT). Previous blood-based and two-dimensional (2D) image-based methods have failed to show a clear dose-response relationship. We developed a three-dimensional (3D) image-based RBM dosimetry approach using the Monte Carlo-based 3D radiobiological dosimetry (3D-RD) software and determined its additional value for predicting RBM toxicity. RBM doses were calculated for 13 colorectal cancer patients after pretargeted RIT with the two-step administration of an anti-CEA × anti-HSG bispecific monoclonal antibody and a (177)Lu-labeled di-HSG-peptide. 3D-RD RBM dosimetry was based on the lumbar vertebrae, delineated on single photon emission computed tomography (SPECT) scans acquired directly, 3, 24, and 72 h after (177)Lu administration. RBM doses were correlated to hematologic effects, according to NCI-CTC v3 and compared with conventional 2D cranium-based and blood-based dosimetry results. Tumor doses were calculated with 3D-RD, which has not been possible with 2D dosimetry. Tumor-to-RBM dose ratios were calculated and compared for (177)Lu-based pretargeted RIT and simulated pretargeted RIT with (90)Y. 3D-RD RBM doses of all seven patients who developed thrombocytopenia were higher (range 0.43 to 0.97 Gy) than that of the six patients without thrombocytopenia (range 0.12 to 0.39 Gy), except in one patient (0.47 Gy) without thrombocytopenia but with grade 2 leucopenia. Blood and 2D image-based RBM doses for patients with grade 1 to 2 thrombocytopenia were in the same range as in patients without thrombocytopenia (0.14 to 0.29 and 0.11 to 0.26 Gy, respectively). Blood-based RBM doses for two grade 3 to 4 patients were higher (0.66 and 0.51 Gy, respectively) than the others, and the cranium-based dose of only the grade 4 patient was higher (0.34 Gy). Tumor-to-RBM dose ratios would increase by 25% on average when treating with (90)Y instead of (177)Lu. 3D dosimetry identifies

Nonuniform Irradiation of the Canine Intestine. 2. Dosimetry

DTIC Science & Technology

1990-01-01

irradiation is accurate assessment In vivo dosimetry was done using Harshaw (Solon, Ohio) TLD - 100 lith- of the injury after either accidental or... vivo TLD dosimetry system allowed measure- 5 and 6. The dose was determined from the median TLD ment of the °Co dose deposited in the canine small...provide replicate measurements. Two separate dosimetry tubes were deveoped (Fig. 1). The first contained 30 TLD cap- doses (1). Nevertheless, current

Dosimetry of ionising radiation in modern radiation oncology

NASA Astrophysics Data System (ADS)

Kron, Tomas; Lehmann, Joerg; Greer, Peter B.

2016-07-01

Dosimetry of ionising radiation is a well-established and mature branch of physical sciences with many applications in medicine and biology. In particular radiotherapy relies on dosimetry for optimisation of cancer treatment and avoidance of severe toxicity for patients. Several novel developments in radiotherapy have introduced new challenges for dosimetry with small and dynamically changing radiation fields being central to many of these applications such as stereotactic ablative body radiotherapy and intensity modulated radiation therapy. There is also an increasing awareness of low doses given to structures not in the target region and the associated risk of secondary cancer induction. Here accurate dosimetry is important not only for treatment optimisation but also for the generation of data that can inform radiation protection approaches in the future. The article introduces some of the challenges and highlights the interdependence of dosimetric calculations and measurements. Dosimetric concepts are explored in the context of six application fields: reference dosimetry, small fields, low dose out of field, in vivo dosimetry, brachytherapy and auditing of radiotherapy practice. Recent developments of dosimeters that can be used for these purposes are discussed using spatial resolution and number of dimensions for measurement as sorting criteria. While dosimetry is ever evolving to address the needs of advancing applications of radiation in medicine two fundamental issues remain: the accuracy of the measurement from a scientific perspective and the importance to link the measurement to a clinically relevant question. This review aims to provide an update on both of these.

A reusable OSL-film for 2D radiotherapy dosimetry

NASA Astrophysics Data System (ADS)

Wouter, Crijns; Dirk, Vandenbroucke; Paul, Leblans; Tom, Depuydt

2017-11-01

Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Z eff). The current work studied the applicability of a 2D OSL-film with a reduced Z eff as (IMRT/VMAT) dosimeter. Based on their commercial OSL-film experience, Agfa Healthcare N.V. produced a new experimental OSL-film for RT dosimetry. This film had a lower effective atomic number compared to the films used in radiology. Typical 2D dosimeter requirements such as uniformity, dose response, signal stability with time, and angular dependence were evaluated. Additionally, the impact of a possible residual energy dependence was assessed for the infield as well as the out-of-field region of both static beams and standard intensity modulated patterns (chair and pyramid). The OSL-film’s reusable nature allowed for a film specific absolute and linear calibration including a flood-field uniformity correction. The OSL-film was scanned with a CR-15X engine based reader using a strict timing (i.e. 4 min after ‘beam on’ or as soon as possible) to account for spontaneous recombination. The OSL-film had good basic response properties: non-uniformities  ⩽2.6%, a linear dose response (0-32 Gy), a linear signal decay (0.5% min-1) over the 20 min measured, and limited angular dependence  ⩽2.6%. Due to variations of the energy spectrum, larger dose differences were noted outside the central region of the homogenous phantom and outside both static and IMRT fields. However, the OSL-film’s measured dose differences of the IMRT patterns were lower than those of Gafchromic EBT measurements ([-1.6%, 2.1%] versus [-2.9%, 3.6%]). The current OSL-film could be used as a reusable high resolution dosimeter with read-out immediately after

A reusable OSL-film for 2D radiotherapy dosimetry.

PubMed

Wouter, Crijns; Dirk, Vandenbroucke; Paul, Leblans; Tom, Depuydt

2017-10-19

Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Z eff ). The current work studied the applicability of a 2D OSL-film with a reduced Z eff as (IMRT/VMAT) dosimeter. Based on their commercial OSL-film experience, Agfa Healthcare N.V. produced a new experimental OSL-film for RT dosimetry. This film had a lower effective atomic number compared to the films used in radiology. Typical 2D dosimeter requirements such as uniformity, dose response, signal stability with time, and angular dependence were evaluated. Additionally, the impact of a possible residual energy dependence was assessed for the infield as well as the out-of-field region of both static beams and standard intensity modulated patterns (chair and pyramid). The OSL-film's reusable nature allowed for a film specific absolute and linear calibration including a flood-field uniformity correction. The OSL-film was scanned with a CR-15X engine based reader using a strict timing (i.e. 4 min after 'beam on' or as soon as possible) to account for spontaneous recombination. The OSL-film had good basic response properties: non-uniformities  ⩽2.6%, a linear dose response (0-32 Gy), a linear signal decay (0.5% min -1 ) over the 20 min measured, and limited angular dependence  ⩽2.6%. Due to variations of the energy spectrum, larger dose differences were noted outside the central region of the homogenous phantom and outside both static and IMRT fields. However, the OSL-film's measured dose differences of the IMRT patterns were lower than those of Gafchromic EBT measurements ([-1.6%, 2.1%] versus [-2.9%, 3.6%]). The current OSL-film could be used as a reusable high resolution dosimeter with read-out immediately after irradiation

Verification of an on line in vivo semiconductor dosimetry system for TBI with two TLD procedures.

PubMed

Sánchez-Doblado, F; Terrón, J A; Sánchez-Nieto, B; Arráns, R; Errazquin, L; Biggs, D; Lee, C; Núñez, L; Delgado, A; Muñiz, J L

1995-01-01

This work presents the verification of an on line in vivo dosimetry system based on semiconductors. Software and hardware has been designed to convert the diode signal into absorbed dose. Final verification was made in the form of an intercomparison with two independent thermoluminiscent (TLD) dosimetry systems, under TBI conditions.

The physics of small megavoltage photon beam dosimetry.

PubMed

Andreo, Pedro

2018-02-01

The increased interest during recent years in the use of small megavoltage photon beams in advanced radiotherapy techniques has led to the development of dosimetry recommendations by different national and international organizations. Their requirement of data suitable for the different clinical options available, regarding treatment units and dosimetry equipment, has generated a considerable amount of research by the scientific community during the last decade. The multiple publications in the field have led not only to the availability of new invaluable data, but have also contributed substantially to an improved understanding of the physics of their dosimetry. This work provides an overview of the most important aspects that govern the physics of small megavoltage photon beam dosimetry. Copyright © 2017 Elsevier B.V. All rights reserved.

Electron paramagnetic resonance (EPR) dosimetry using lithium formate in radiotherapy: comparison with thermoluminescence (TL) dosimetry using lithium fluoride rods.

PubMed

Vestad, Tor Arne; Malinen, Eirik; Olsen, Dag Rune; Hole, Eli Olaug; Sagstuen, Einar

2004-10-21

Solid-state radiation dosimetry by electron paramagnetic resonance (EPR) spectroscopy and thermoluminescence (TL) was utilized for the determination of absorbed doses in the range of 0.5-2.5 Gy. The dosimeter materials used were lithium formate and lithium fluoride (TLD-100 rods) for EPR dosimetry and TL dosimetry, respectively. 60Co gamma-rays and 4, 6, 10 and 15 MV x-rays were employed. The main objectives were to compare the variation in dosimeter reading of the respective dosimetry systems and to determine the photon energy dependence of the two dosimeter materials. The EPR dosimeter sensitivity was constant over the dose range in question, while the TL sensitivity increased by more than 5% from 0.5 to 2.5 Gy, thus displaying a supralinear dose response. The average relative standard deviation in the dosimeter reading per dose was 3.0% and 1.2% for the EPR and TL procedures, respectively. For EPR dosimeters, the relative standard deviation declined significantly from 4.3% to 1.1% over the dose range in question. The dose-to-water energy response for the megavoltage x-ray beams relative to 60Co gamma-rays was in the range of 0.990-0.979 and 0.984-0.962 for lithium formate and lithium fluoride, respectively. The results show that EPR dosimetry with lithium formate provides dose estimates with a precision comparable to that of TL dosimetry (using lithium fluoride) for doses above 2 Gy, and that lithium formate is slightly less dependent on megavoltage photon beam energy than lithium fluoride.

Electron paramagnetic resonance (EPR) dosimetry using lithium formate in radiotherapy: comparison with thermoluminescence (TL) dosimetry using lithium fluoride rods

NASA Astrophysics Data System (ADS)

Vestad, Tor Arne; Malinen, Eirik; Rune Olsen, Dag; Olaug Hole, Eli; Sagstuen, Einar

2004-10-01

Solid-state radiation dosimetry by electron paramagnetic resonance (EPR) spectroscopy and thermoluminescence (TL) was utilized for the determination of absorbed doses in the range of 0.5-2.5 Gy. The dosimeter materials used were lithium formate and lithium fluoride (TLD-100 rods) for EPR dosimetry and TL dosimetry, respectively. 60Co ggr-rays and 4, 6, 10 and 15 MV x-rays were employed. The main objectives were to compare the variation in dosimeter reading of the respective dosimetry systems and to determine the photon energy dependence of the two dosimeter materials. The EPR dosimeter sensitivity was constant over the dose range in question, while the TL sensitivity increased by more than 5% from 0.5 to 2.5 Gy, thus displaying a supralinear dose response. The average relative standard deviation in the dosimeter reading per dose was 3.0% and 1.2% for the EPR and TL procedures, respectively. For EPR dosimeters, the relative standard deviation declined significantly from 4.3% to 1.1% over the dose range in question. The dose-to-water energy response for the megavoltage x-ray beams relative to 60Co ggr-rays was in the range of 0.990-0.979 and 0.984-0.962 for lithium formate and lithium fluoride, respectively. The results show that EPR dosimetry with lithium formate provides dose estimates with a precision comparable to that of TL dosimetry (using lithium fluoride) for doses above 2 Gy, and that lithium formate is slightly less dependent on megavoltage photon beam energy than lithium fluoride.

Dosimetry of high-energy electron linac produced photoneutrons and the bremsstrahlung gamma-rays using TLD-500 and TLD-700 dosimeter pairs

NASA Astrophysics Data System (ADS)

Mukherjee, Bhaskar; Makowski, Dariusz; Simrock, Stefan

2005-06-01

The neutron and gamma doses are crucial to interpreting the radiation effects in microelectronic devices operating in a high-energy accelerator environment. This report highlights a method for an accurate estimation of photoneutron and the accompanying bremsstrahlung (gamma) doses produced by a 450 MeV electron linear accelerator (linac) operating in pulsed mode. The principle is based on the analysis of thermoluminescence glow-curves of TLD-500 (Aluminium Oxide) and TLD-700 (Lithium Fluoride) dosimeter pairs. The gamma and fast neutron response of the TLD-500 and TLD-700 dosimeter pairs were calibrated with a 60Co (gamma) and a 241Am-Be (α, n) neutron standard-source, respectively. The Kinetic Energy Released in Materials (kerma) conversion factor for photoneutrons was evaluated by folding the neutron kerma (dose) distribution in 7LiF (the main component of the TLD-700 dosimeter) with the energy spectra of the 241Am-Be (α, n) neutrons and electron accelerator produced photoneutrons. The neutron kerma conversion factors for 241Am-Be neutrons and photoneutrons were calculated to be 2.52×10 -3 and 1.37×10 -3 μGy/a.u. respectively. The bremsstrahlung (gamma) dose conversion factor was evaluated to be 7.32×10 -4 μGy/a.u. The above method has been successfully utilised to assess the photoneutron and bremsstrahlung doses from a 450 MeV electron linac operating at DESY Research Centre in Hamburg, Germany.

Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities.

PubMed

Behrens, R

2012-09-01

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, H(p)(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to H(p)(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037.

Calibration of a mosfet detection system for 6-MV in vivo dosimetry.

PubMed

Scalchi, P; Francescon, P

1998-03-01

dosimetry within 5%. Ionization chamber and MOSFET midplane dosimetry in inhomogeneous phantoms are in agreement within 2%. MOSFET characteristics are suitable for the in vivo dosimetry relevant to 6-MV treatments, both in normal and TBI setup. The TBI midplane dosimetry using MOSFETs is valid also in the presence of the lung, which is the most critical organ, and allows verifying that calculation of the lung attenuator thicknesses based only on the density is not correct. Our MOSFET dosimetry system can be used also to determine the surface dose by using the water-equivalent depth and extrapolation methods. This procedure depends on the field size used.

Dosimetry with diamond detectors

NASA Astrophysics Data System (ADS)

Gervino, G.; Marino, C.; Silvestri, F.; Lavagno, A.; Truc, F.

2010-05-01

In this paper we present the dosimetry analysis in terms of stability and repeatability of the signal and dose rate dependence of a synthetic single crystal diamond grown by Chemical Vapor Deposition (CVD) technique. The measurements carried out by 5 MeV X-ray photons beam show very promising results, even if the dose rate detector response points out that the charge trapping centers distribution is not uniform inside the crystal volume. This handicap that affects the detectors performances, must be ascribed to the growing process. Synthetic single crystal diamonds could be a valuable alternative to air ionization chambers for quality beam control and for intensity modulated radiation therapy beams dosimetry.

SU-G-201-10: Experimental Determination of Modified TG-43 Dosimetry Parameters for the Xoft Axxent® Electronic Brachytherapy Source

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

Simiele, S; Palmer, B; DeWerd, L

Purpose: The establishment of an air kerma rate standard at NIST for the Xoft Axxent{sup ®} electronic brachytherapy source (Axxent{sup ®} source) motivated the establishment of a modified TG-43 dosimetry formalism. This work measures the modified dosimetry parameters for the Axxent{sup ®} source in the absence of a treatment applicator for implementation in Xoft’s treatment planning system. Methods: The dose-rate conversion coefficient (DRCC), radial dose function (RDF) values, and polar anisotropy (PA) were measured using TLD-100 microcubes with NIST-calibrated sources. The DRCC and RDF measurements were performed in liquid water using an annulus of Virtual Water™ designed to align themore » TLDs at the height of the anode at fixed radii from the source. The PA was measured at several distances from the source in a PMMA phantom. MCNP-determined absorbed dose energy dependence correction factors were used to convert from dose to TLD to dose to liquid water for the DRCC, RDF, and PA measurements. The intrinsic energy dependence correction factor from the work of Pike was used. The AKR was determined using a NIST-calibrated HDR1000 Plus well-type ionization chamber. Results: The DRCC was determined to be 8.6 (cGy/hr)/(µGy/min). The radial dose values were determined to be 1.00 (1cm), 0.60 (2cm), 0.42 (3cm), and 0.32 (4cm), with agreement ranging from (5.7% to 10.9%) from the work of Hiatt et al. 2015 and agreement from (2.8% to 6.8%) with internal MCNP simulations. Conclusion: This work presents a complete dataset of modified TG-43 dosimetry parameters for the Axxent{sup ®} source in the absence of an applicator. Prior to this study a DRCC had not been measured for the Axxent{sup ®} source. This data will be used for calculating dose distributions for patients receiving treatment with the Axxent{sup ®} source in Xoft’s breast balloon and vaginal applicators, and for intraoperative radiotherapy. Sources and partial funding for this work were provided

Clinical application of the OneDose™ Patient Dosimetry System for total body irradiation

NASA Astrophysics Data System (ADS)

Best, S.; Ralston, A.; Suchowerska, N.

2005-12-01

The OneDose™ Patient Dosimetry System (Sicel Technologies) is a new dosimeter based on metal oxide semiconductor field-effect transistor technology and designed for the in vivo measurement of patient dose during radiotherapy. In vivo dosimetry for total body irradiation (TBI) is challenging due to the extended treatment distance, low dose rates and beam spoilers. Phantom results confirm the suitability of the dosimeter for TBI in terms of inherent build-up, post-irradiation fading, accuracy, reproducibility, linearity and temperature dependence. Directional dependence is significant and should be taken into account. The OneDose™ dosimeters were also trialed in vivo for two TBI patients and the dose measured compared to conventional dosimeter measurements using an ionization chamber and thermoluminescent dosimeters (TLD), with agreement to within 2.2% and 3.9%, respectively. Phantom and patient results confirm that the OneDose™ patient dosimetry system is a practical and convenient alternative to TLDs for TBI in vivo dosimetry. For increased confidence in results with this dosimeter, we recommend that two dosimeters be used for each site of interest.

Clinical application of the OneDose Patient Dosimetry System for total body irradiation.

PubMed

Best, S; Ralston, A; Suchowerska, N

2005-12-21

The OneDose Patient Dosimetry System (Sicel Technologies) is a new dosimeter based on metal oxide semiconductor field-effect transistor technology and designed for the in vivo measurement of patient dose during radiotherapy. In vivo dosimetry for total body irradiation (TBI) is challenging due to the extended treatment distance, low dose rates and beam spoilers. Phantom results confirm the suitability of the dosimeter for TBI in terms of inherent build-up, post-irradiation fading, accuracy, reproducibility, linearity and temperature dependence. Directional dependence is significant and should be taken into account. The OneDose dosimeters were also trialed in vivo for two TBI patients and the dose measured compared to conventional dosimeter measurements using an ionization chamber and thermoluminescent dosimeters (TLD), with agreement to within 2.2% and 3.9%, respectively. Phantom and patient results confirm that the OneDose patient dosimetry system is a practical and convenient alternative to TLDs for TBI in vivo dosimetry. For increased confidence in results with this dosimeter, we recommend that two dosimeters be used for each site of interest.

The IROC Houston Quality Assurance Program: Potential benefits of 3D dosimetry

NASA Astrophysics Data System (ADS)

Followill, D. S.; Molineu, H. A.; Lafratta, R.; Ibbott, G. S.

2017-05-01

The IROC Houston QA Center has provided QA core support for NCI clinical trials by ensuring that radiation doses delivered to trial patients are accurate and comparable between participating institutions. Within its QA program, IROC Houston uses anthropomorphic QA phantoms to credential sites. It is these phantoms that have the highest potential to benefit from the use of 3D dosimeters. Credentialing is performed to verify that institutions that are using advanced technologies to deliver complex treatment plans that conform to targets. This makes it increasingly difficult to assure the intended calculated dose is being delivered correctly using current techniques that are 2D-based. A 3D dosimeter such as PRESAGE® is able to provide a complete 3D measured dosimetry dataset with one treatment plan delivery. In our preliminary studies, the 3D dosimeters in our H&N and spine phantoms were found to be appropriate for remote dosimetry for relative dose measurements. To implement 3D dosimetry in IROC Houston’s phantoms, the benefit of this significant change to its current infrastructure would have to be assessed and further work would be needed before bringing 3D dosimeters into the phantom dosimetry program.

Computer Aided Dosimetry and Verification of Exposure to Radiation

DTIC Science & Technology

2002-06-01

Event matrix 2. Hematopoietic * Absolute blood counts * Relative blood counts 3. Dosimetry * TLD * EPDQuantitative * Radiation survey * Whole body...EI1 Defence Research and Recherche et developpement Development Canada pour la d6fense Canada DEFENCE •mI•DEFENSE Computer Aided Dosimetry and...Aided Dosimetry and Verification of Exposure to Radiation Edward Waller SAIC Canada Robert Z Stodilka Radiation Effects Group, Space Systems and

Development, validation, and implementation of a patient-specific Monte Carlo 3D internal dosimetry platform

NASA Astrophysics Data System (ADS)

Besemer, Abigail E.

Targeted radionuclide therapy is emerging as an attractive treatment option for a broad spectrum of tumor types because it has the potential to simultaneously eradicate both the primary tumor site as well as the metastatic disease throughout the body. Patient-specific absorbed dose calculations for radionuclide therapies are important for reducing the risk of normal tissue complications and optimizing tumor response. However, the only FDA approved software for internal dosimetry calculates doses based on the MIRD methodology which estimates mean organ doses using activity-to-dose scaling factors tabulated from standard phantom geometries. Despite the improved dosimetric accuracy afforded by direct Monte Carlo dosimetry methods these methods are not widely used in routine clinical practice because of the complexity of implementation, lack of relevant standard protocols, and longer dose calculation times. The main goal of this work was to develop a Monte Carlo internal dosimetry platform in order to (1) calculate patient-specific voxelized dose distributions in a clinically feasible time frame, (2) examine and quantify the dosimetric impact of various parameters and methodologies used in 3D internal dosimetry methods, and (3) develop a multi-criteria treatment planning optimization framework for multi-radiopharmaceutical combination therapies. This platform utilizes serial PET/CT or SPECT/CT images to calculate voxelized 3D internal dose distributions with the Monte Carlo code Geant4. Dosimetry can be computed for any diagnostic or therapeutic radiopharmaceutical and for both pre-clinical and clinical applications. In this work, the platform's dosimetry calculations were successfully validated against previously published reference doses values calculated in standard phantoms for a variety of radionuclides, over a wide range of photon and electron energies, and for many different organs and tumor sizes. Retrospective dosimetry was also calculated for various pre

Key comparison BIPM.RI(I)-K5 of the air-kerma standards of the SMU, Slovakia and the BIPM in 137Cs gamma radiation

NASA Astrophysics Data System (ADS)

Kessler, C.; Burns, D.; Durný, N.

2018-01-01

The first direct comparison of the standards for air kerma of the Slovak Institute of Metrology (SMU), Slovakia and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in June 2017. The comparison result, evaluated as a ratio of the SMU and the BIPM standards for air kerma, is 1.0051 with a combined standard uncertainty of 2.7 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 2 parts in 104. The results are analysed and presented in terms of degrees of equivalence, suitable 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).

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the SMU, Slovakia and the BIPM in 60Co gamma radiation

NASA Astrophysics Data System (ADS)

Kessler, C.; Burns, D.; Durný, N.

2018-01-01

A key comparison of the standards for air kerma of the Slovak Institute of Metrology (SMU), Slovakia and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in June 2017. The comparison result, evaluated as a ratio of the SMU and the BIPM standards for air kerma, is 1.0042 with a combined standard uncertainty of 2.7 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 2 parts in 104. The results are analysed and presented in terms of degrees of equivalence, suitable 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).

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the MKEH, Hungary and the BIPM in 60Co gamma radiation

NASA Astrophysics Data System (ADS)

Kessler, C.; Burns, D.; Machula, G.

2018-01-01

A comparison of the standards for air kerma of the Hungarian Trade Licensing Office (MKEH), Hungary and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in March 2016. The comparison result, evaluated as a ratio of the MKEH and the BIPM standards for air kerma, is 1.0047 with a combined standard uncertainty of 1.9 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 2.6 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable 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).

Prediction of internal dosimetry and toxicity of volatile chemicals in rats using physiologically based pharmacokinetic modeling: carbon tetrachloride as a model compound

EPA Science Inventory

Prediction of internal dosimetry and toxicity of volatile chemicals in rats using physiologically based pharmacokinetic modeling: carbon tetrachloride as a model compound D.N. Williams1, J.E. Simmons2, J.V. Bruckner3, and M.V. Evans2 1ORISE, Oak Ridge, TN 37831-0117; 2US EPA/ORD/...

Introduction of a deformable x-ray CT polymer gel dosimetry system

NASA Astrophysics Data System (ADS)

Maynard, E.; Heath, E.; Hilts, M.; Jirasek, A.

2018-04-01

This study introduces the first 3D deformable dosimetry system based on x-ray computed tomography (CT) polymer gel dosimetry and establishes the setup reproducibility, deformation characteristics and dose response of the system. A N-isopropylacrylamide (NIPAM)-based gel formulation optimized for x-ray CT gel dosimetry was used, with a latex balloon serving as the deformable container and low-density polyethylene and polyvinyl alcohol providing additional oxygen barrier. Deformable gels were irradiated with a 6 MV calibration pattern to determine dosimetric response and a dosimetrically uniform plan to determine the spatial uniformity of the response. Wax beads were added to each gel as fiducial markers to track the deformation and setup of the gel dosimeters. From positions of the beads on CT images the setup reproducibility and the limits and reproducibility of gel deformation were determined. Comparison of gel measurements with Monte Carlo dose calculations found excellent dosimetric accuracy, comparable to that of an established non-deformable dosimetry system, with a mean dose discrepancy of 1.5% in the low-dose gradient region and a gamma pass rate of 97.9% using a 3%/3 mm criterion. The deformable dosimeter also showed good overall spatial dose uniformity throughout the dosimeter with some discrepancies within 20 mm of the edge of the container. Tracking of the beads within the dosimeter found that sub-millimetre setup accuracy is achievable with this system. The dosimeter was able to deform and relax when externally compressed by up to 30 mm without sustaining any permanent damage. Internal deformations in 3D produced average marker movements of up to 12 mm along the direction of compression. These deformations were also shown to be reproducible over 100 consecutive deformations. This work has established several important characteristics of a new deformable dosimetry system which shows promise for future clinical applications, including the

Pilot program on patient dosimetry in pediatric interventional cardiology in Chile

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

Ubeda, Carlos; Vano, Eliseo; Miranda, Patricia

2012-05-15

Purpose: The aim of this study was to present the results of a pilot program on patient dosimetry carried out in Chile during the last 5 yr, using a biplane x-ray angiography system settled for pediatrics. This research was conducted in Latin America under the auspices of the International Atomic Energy Agency (IAEA) supporting programs on radiological protection (RP) of patients. Methods: Patient age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time, and two dosimetric quantities [air kerma-area product (P{sub ka}) and cumulative dose (CD) at the patient entrance reference point] were recorded formore » each procedure. Results: The study includes 544 patients grouped into four age groups. The distributions by age group were 150 for <1 yr; 203 for 1 to <5 yr; 97 for 5 to <10 yr; and 94 for 10 to <16 yr. Median values of P{sub ka} and CD for the four age groups were 0.94, 1.46, 2.13, and 5.03 Gy cm{sup 2} and 23.9, 26.8, 33.5, and 51.6 mGy, respectively. No significant statistical differences were found between diagnostic and therapeutic procedures. A moderate correlation (r = 0.64) was seen between P{sub ka} and patient weight. Conclusions: The dose values reported in this paper were lower than those published in the previous work for the same age groups as a result of the optimization actions carried out by cardiologists and medical physicists with the support of the IAEA. Methodology and results will be used as a starting point for a wider survey in Chile and Latin America with the goal to obtain regional diagnostic reference levels as recently recommended by the International Commission on Radiological Protection for interventional procedures.« less

Gene expression-based dosimetry by dose and time in mice following acute radiation exposure.

PubMed

Tucker, James D; Divine, George W; Grever, William E; Thomas, Robert A; Joiner, Michael C; Smolinski, Joseph M; Auner, Gregory W

2013-01-01

Rapid and reliable methods for performing biological dosimetry are of paramount importance in the event of a large-scale nuclear event. Traditional dosimetry approaches lack the requisite rapid assessment capability, ease of use, portability and low cost, which are factors needed for triaging a large number of victims. Here we describe the results of experiments in which mice were acutely exposed to (60)Co gamma rays at doses of 0 (control) to 10 Gy. Blood was obtained from irradiated mice 0.5, 1, 2, 3, 5, and 7 days after exposure. mRNA expression levels of 106 selected genes were obtained by reverse-transcription real time PCR. Stepwise regression of dose received against individual gene transcript expression levels provided optimal dosimetry at each time point. The results indicate that only 4-7 different gene transcripts are needed to explain ≥ 0.69 of the variance (R(2)), and that receiver-operator characteristics, a measure of sensitivity and specificity, of ≥ 0.93 for these statistical models were achieved at each time point. These models provide an excellent description of the relationship between the actual and predicted doses up to 6 Gy. At doses of 8 and 10 Gy there appears to be saturation of the radiation-response signals with a corresponding diminution of accuracy. These results suggest that similar analyses in humans may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations.

Retrospective dosimetry analyses of reactor vessel cladding samples

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

Greenwood, L. R.; Soderquist, C. Z.; Fero, A. H.

2011-07-01

Reactor pressure vessel cladding samples for Ringhals Units 3 and 4 in Sweden were analyzed using retrospective reactor dosimetry techniques. The objective was to provide the best estimates of the neutron fluence for comparison with neutron transport calculations. A total of 51 stainless steel samples consisting of chips weighing approximately 100 to 200 mg were removed from selected locations around the pressure vessel and were sent to Pacific Northwest National Laboratory for analysis. The samples were fully characterized and analyzed for radioactive isotopes, with special interest in the presence of Nb-93m. The RPV cladding retrospective dosimetry results will be combinedmore » with a re-evaluation of the surveillance capsule dosimetry and with ex-vessel neutron dosimetry results to form a comprehensive 3D comparison of measurements to calculations performed with 3D deterministic transport code. (authors)« less

SU-E-T-90: Accuracy of Calibration of Lithium-6 and -7 Enriched LiF TLDs for Neutron Measurements in High Energy Radiotherapy

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

Keehan, S; Franich, R; Taylor, M

Purpose: To determine the potential error involved in the interpretation of neutron measurements from medical linear accelerators (linacs) using TLD-600H and TLD-700H if standard AmBe and {sup 252}Cf neutron sources are used for calibration without proper inclusion of neutron energy spectrum information. Methods: The Kerma due to neutrons can be calculated from the energy released by various nuclear interactions (elastic and inelastic scatter, (n,α), (n,p), (n,d), (n,t), (n,2n), etc.). The response of each TLD can be considered the sum of the neutron and gamma components; each proportional to the Kerma. Using the difference between the measured TLD responses and themore » ratio of the calculated Kerma for each material, the neutron component of the response can be calculated. The Monte Carlo code MCNP6 has been used to calculate the neutron energy spectra resulting from photonuclear interactions in a Varian 21EX linac. TLDs have been exposed to the mixed (γ-n) field produced by a linac and AmBe and {sup 252}Cf standard neutron sources. Results: For dosimetry of neutrons from AmBe or {sup 252}Cf sources, assuming TLD-700H insensitivity to neutrons will Result in 10% or 20% overestimation of neutron doses respectively.For dosimetry of neutrons produced in a Varian 21EX, applying a calibration factor derived from a standard AmBe or {sup 252}Cf source will Result in an overestimation of neutron fluence, by as much as a factor of 47.The assumption of TLD-700H insensitivity to neutrons produced by linacs leads to a negligible error due to the extremely high Kerma ratio (600H/700H) of 3000 for the assumed neutron spectrum. Conclusion: Lithium-enriched TLDs calibrated with AmBe and/or {sup 252}Cf neutron sources are not accurate for use under the neutron energy spectrum produced by a medical linear accelerator.« less

STATUS REPORT: EVIDENCE BASED ADVANCES IN INHALATION DOSIMETRY FOR GASES WITH EFFECTS IN THE LOWER RESPIRATORY TRACT AND IN THE BODY

EPA Science Inventory

This report summarizes the status of specific inhalation dosimetry procedures for gases as outlined in U.S. EPA’s 1994 Methods for Derivation of Inhalation Reference Concentrations and Applications of Inhalation Dosimetry (U.S. EPA 1994) and reviews recent scientific advances in...

Monte Carlo-based diode design for correction-less small field dosimetry.

PubMed

Charles, P H; Crowe, S B; Kairn, T; Knight, R T; Hill, B; Kenny, J; Langton, C M; Trapp, J V

2013-07-07

Due to their small collecting volume, diodes are commonly used in small field dosimetry. However, the relative sensitivity of a diode increases with decreasing small field size. Conversely, small air gaps have been shown to cause a significant decrease in the sensitivity of a detector as the field size is decreased. Therefore, this study uses Monte Carlo simulations to look at introducing air upstream to diodes such that they measure with a constant sensitivity across all field sizes in small field dosimetry. Varying thicknesses of air were introduced onto the upstream end of two commercial diodes (PTW 60016 photon diode and PTW 60017 electron diode), as well as a theoretical unenclosed silicon chip using field sizes as small as 5 mm × 5 mm. The metric D(w,Q)/D(Det,Q) used in this study represents the ratio of the dose to a point of water to the dose to the diode active volume, for a particular field size and location. The optimal thickness of air required to provide a constant sensitivity across all small field sizes was found by plotting D(w,Q)/D(Det,Q) as a function of introduced air gap size for various field sizes, and finding the intersection point of these plots. That is, the point at which D(w,Q)/D(Det,Q) was constant for all field sizes was found. The optimal thickness of air was calculated to be 3.3, 1.15 and 0.10 mm for the photon diode, electron diode and unenclosed silicon chip, respectively. The variation in these results was due to the different design of each detector. When calculated with the new diode design incorporating the upstream air gap, k(f(clin),f(msr))(Q(clin),Q(msr)) was equal to unity to within statistical uncertainty (0.5%) for all three diodes. Cross-axis profile measurements were also improved with the new detector design. The upstream air gap could be implanted on the commercial diodes via a cap consisting of the air cavity surrounded by water equivalent material. The results for the unclosed silicon chip show that an ideal small

Specific issues in small animal dosimetry and irradiator calibration

PubMed Central

Yoshizumi, Terry; Brady, Samuel L.; Robbins, Mike E.; Bourland, J. Daniel

2013-01-01

Purpose In response to the increased risk of radiological terrorist attack, a network of Centers for Medical Countermeasures against Radiation (CMCR) has been established in the United States, focusing on evaluating animal model responses to uniform, relatively homogenous whole- or partial-body radiation exposures at relatively high dose rates. The success of such studies is dependent not only on robust animal models but on accurate and reproducible dosimetry within and across CMCR. To address this issue, the Education and Training Core of the Duke University School of Medicine CMCR organised a one-day workshop on small animal dosimetry. Topics included accuracy in animal dosimetry accuracy, characteristics and differences of cesium-137 and X-ray irradiators, methods for dose measurement, and design of experimental irradiation geometries for uniform dose distributions. This paper summarises the information presented and discussed. Conclusions Without ensuring accurate and reproducible dosimetry the development and assessment of the efficacy of putative countermeasures will not prove successful. Radiation physics support is needed, but is often the weakest link in the small animal dosimetry chain. We recommend: (i) A user training program for new irradiator users, (ii) subsequent training updates, and (iii) the establishment of a national small animal dosimetry center for all CMCR members. PMID:21961967

Whole-remnant and maximum-voxel SPECT/CT dosimetry in {sup 131}I-NaI treatments of differentiated thyroid cancer

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

Mínguez, Pablo, E-mail: pablo.minguezgabina@osakid

Purpose: To investigate the possible differences between SPECT/CT based whole-remnant and maximum-voxel dosimetry in patients receiving radio-iodine ablation treatment of differentiated thyroid cancer (DTC). Methods: Eighteen DTC patients were administered 1.11 GBq of {sup 131}I-NaI after near-total thyroidectomy and rhTSH stimulation. Two patients had two remnants, so in total dosimetry was performed for 20 sites. Three SPECT/CT scans were performed for each patient at 1, 2, and 3–7 days after administration. The activity, the remnant mass, and the maximum-voxel activity were determined from these images and from a recovery-coefficient curve derived from experimental phantom measurements. The cumulated activity was estimatedmore » using trapezoidal-exponential integration. Finally, the absorbed dose was calculated using S-values for unit-density spheres in whole-remnant dosimetry and S-values for voxels in maximum-voxel dosimetry. Results: The mean absorbed dose obtained from whole-remnant dosimetry was 40 Gy (range 2–176 Gy) and from maximum-voxel dosimetry 34 Gy (range 2–145 Gy). For any given patient, the activity concentrations for each of the three time-points were approximately the same for the two methods. The effective half-lives varied (R = 0.865), mainly due to discrepancies in estimation of the longer effective half-lives. On average, absorbed doses obtained from whole-remnant dosimetry were 1.2 ± 0.2 (1 SD) higher than for maximum-voxel dosimetry, mainly due to differences in the S-values. The method-related differences were however small in comparison to the wide range of absorbed doses obtained in patients. Conclusions: Simple and consistent procedures for SPECT/CT based whole-volume and maximum-voxel dosimetry have been described, both based on experimentally determined recovery coefficients. Generally the results from the two approaches are consistent, although there is a small, systematic difference in the absorbed dose due to differences

Radiation dosimetry with fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; Gagliardi, G.; De Natale, P.

2014-05-01

The measurement and monitoring of radiation dose delivered in patient tissues is a critical aspect in radiation therapy. Various dosimeters have proven effective in measuring radiations at low doses. However, there is a growing demand for new dosimeters based on small, non-invasive and high resolution devices. Here we report on a miniature dosimeter based on an optical fiber cavity. We demonstrate an ultimate detection limit of 160 mGy with an effective interaction region of 6 x 10-4 mm3. Due to its reliability, compactness and biomedical dose level sensitivity, our system shows itself suitable for applications in radiation therapy dosimetry.

NOTE: Investigating the potential of polymer gel dosimetry for interventional radiology: first results

NASA Astrophysics Data System (ADS)

Antoniou, P. E.; Bousbouras, P.; Sandaltzopoulos, R.; Kaldoudi, E.

2008-04-01

Complex interventional radiology (IR) procedures contribute an increasing percentage of the overall medical radiation exposure of the population making accurate dosimetry a challenge. Magnetic resonance (MR) based polymer gel dosimetry has been widely employed in complex dosimetric problems in radiotherapy. The aim of this note is to investigate the feasibility of normoxic gel dosimetry in IR. Dose response, energy dependence and dose rate dependence were investigated in irradiation set-ups relevant to IR for a particular normoxic gel, based on methacrylic acid (MAA) as the monomer and including tetrakis-hydroxy-methyl-phosphonium chloride (THPC) as antioxidant. The gel presents a linear dose response beyond a 25 cGy threshold. No significant energy dependence was observed in the useful range of interventional radiology (80-110 kVp). A linear correlation between the gel response and dose rate was observed in the range of dose rates relevant to IR (5-8 cGy min-1). These results demonstrate a reduction of gel sensitivity at very low dose rate levels. A possible explanation of this effect is suggested.

International Standardization of the Clinical Dosimetry of Beta Radiation Brachytherapy Sources: Progress of an ISO Standard

NASA Astrophysics Data System (ADS)

Soares, Christopher

2006-03-01

In 2004 a new work item proposal (NWIP) was accepted by the International Organization for Standardization (ISO) Technical Committee 85 (TC85 -- Nuclear Energy), Subcommittee 2 (Radiation Protection) for the development of a standard for the clinical dosimetry of beta radiation sources used for brachytherapy. To develop this standard, a new Working Group (WG 22 - Ionizing Radiation Dosimetry and Protocols in Medical Applications) was formed. The standard is based on the work of an ad-hoc working group initiated by the Dosimetry task group of the Deutsches Insitiut für Normung (DIN). Initially the work was geared mainly towards the needs of intravascular brachytherapy, but with the decline of this application, more focus has been placed on the challenges of accurate dosimetry for the concave eye plaques used to treat ocular melanoma. Guidance is given for dosimetry formalisms, reference data to be used, calibrations, measurement methods, modeling, uncertainty determinations, treatment planning and reporting, and clinical quality control. The document is currently undergoing review by the ISO member bodies for acceptance as a Committee Draft (CD) with publication of the final standard expected by 2007. There are opportunities for other ISO standards for medical dosimetry within the framework of WG22.

Overview of physical dosimetry methods for triage application integrated in the new European network RENEB.

PubMed

Trompier, François; Burbidge, Christopher; Bassinet, Céline; Baumann, Marion; Bortolin, Emanuela; De Angelis, Cinzia; Eakins, Jonathan; Della Monaca, Sara; Fattibene, Paola; Quattrini, Maria Cristina; Tanner, Rick; Wieser, Albrecht; Woda, Clemens

2017-01-01

In the EC-funded project RENEB (Realizing the European Network in Biodosimetry), physical methods applied to fortuitous dosimetric materials are used to complement biological dosimetry, to increase dose assessment capacity for large-scale radiation/nuclear accidents. This paper describes the work performed to implement Optically Stimulated Luminescence (OSL) and Electron Paramagnetic Resonance (EPR) dosimetry techniques. OSL is applied to electronic components and EPR to touch-screen glass from mobile phones. To implement these new approaches, several blind tests and inter-laboratory comparisons (ILC) were organized for each assay. OSL systems have shown good performances. EPR systems also show good performance in controlled conditions, but ILC have also demonstrated that post-irradiation exposure to sunlight increases the complexity of the EPR signal analysis. Physically-based dosimetry techniques present high capacity, new possibilities for accident dosimetry, especially in the case of large-scale events. Some of the techniques applied can be considered as operational (e.g. OSL on Surface Mounting Devices [SMD]) and provide a large increase of measurement capacity for existing networks. Other techniques and devices currently undergoing validation or development in Europe could lead to considerable increases in the capacity of the RENEB accident dosimetry network.

Thermoluminescence Dosimetry (TLD) and its Application in Medical Physics

NASA Astrophysics Data System (ADS)

Azorín Nieto, Juan

2004-09-01

Radiation dosimetry is fundamental in Medical Physics, involving patients and phantom dosimetry. In both cases thermoluminescence dosimetry (TLD) is the most appropriate technique for measuring the absorbed dose. In this paper thermoluminescence phenomenon as well as the use of TLD in radiodiagnosis and radiotherapy for in vivo or in phantom measurements is discussed. Some results of measurements made in radiotherapy and radiodiagnosis using home made LiF:Mg,Cu,P+PTFE TLD are presented.

Evaluation and implementation of triple‐channel radiochromic film dosimetry in brachytherapy

PubMed Central

Bradley, David; Nisbet, Andrew

2014-01-01

The measurement of dose distributions in clinical brachytherapy, for the purpose of quality control, commissioning or dosimetric audit, is challenging and requires development. Radiochromic film dosimetry with a commercial flatbed scanner may be suitable, but careful methodologies are required to control various sources of uncertainty. Triple‐channel dosimetry has recently been utilized in external beam radiotherapy to improve the accuracy of film dosimetry, but its use in brachytherapy, with characteristic high maximum doses, steep dose gradients, and small scales, has been less well researched. We investigate the use of advanced film dosimetry techniques for brachytherapy dosimetry, evaluating uncertainties and assessing the mitigation afforded by triple‐channel dosimetry. We present results on postirradiation film darkening, lateral scanner effect, film surface perturbation, film active layer thickness, film curling, and examples of the measurement of clinical brachytherapy dose distributions. The lateral scanner effect in brachytherapy film dosimetry can be very significant, up to 23% dose increase at 14 Gy, at ± 9 cm lateral from the scanner axis for simple single‐channel dosimetry. Triple‐channel dosimetry mitigates the effect, but still limits the useable width of a typical scanner to less than 8 cm at high dose levels to give dose uncertainty to within 1%. Triple‐channel dosimetry separates dose and dose‐independent signal components, and effectively removes disturbances caused by film thickness variation and surface perturbations in the examples considered in this work. The use of reference dose films scanned simultaneously with brachytherapy test films is recommended to account for scanner variations from calibration conditions. Postirradiation darkening, which is a continual logarithmic function with time, must be taken into account between the reference and test films. Finally, films must be flat when scanned to avoid the Callier�

Synchrotron-based coherent scatter x-ray projection imaging using an array of monoenergetic pencil beams.

PubMed

Landheer, Karl; Johns, Paul C

2012-09-01

Traditional projection x-ray imaging utilizes only the information from the primary photons. Low-angle coherent scatter images can be acquired simultaneous to the primary images and provide additional information. In medical applications scatter imaging can improve x-ray contrast or reduce dose using information that is currently discarded in radiological images to augment the transmitted radiation information. Other applications include non-destructive testing and security. A system at the Canadian Light Source synchrotron was configured which utilizes multiple pencil beams (up to five) to create both primary and coherent scatter projection images, simultaneously. The sample was scanned through the beams using an automated step-and-shoot setup. Pixels were acquired in a hexagonal lattice to maximize packing efficiency. The typical pitch was between 1.0 and 1.6 mm. A Maximum Likelihood-Expectation Maximization-based iterative method was used to disentangle the overlapping information from the flat panel digital x-ray detector. The pixel value of the coherent scatter image was generated by integrating the radial profile (scatter intensity versus scattering angle) over an angular range. Different angular ranges maximize the contrast between different materials of interest. A five-beam primary and scatter image set (which had a pixel beam time of 990 ms and total scan time of 56 min) of a porcine phantom is included. For comparison a single-beam coherent scatter image of the same phantom is included. The muscle-fat contrast was 0.10 ± 0.01 and 1.16 ± 0.03 for the five-beam primary and scatter images, respectively. The air kerma was measured free in air using aluminum oxide optically stimulated luminescent dosimeters. The total area-averaged air kerma for the scan was measured to be 7.2 ± 0.4 cGy although due to difficulties in small-beam dosimetry this number could be inaccurate.

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

Williamson, Jeffrey F.

This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as amore » means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.« less

Personal exposure to mobile phone frequencies and well-being in adults: a cross-sectional study based on dosimetry.

PubMed

Thomas, Silke; Kühnlein, Anja; Heinrich, Sabine; Praml, Georg; Nowak, Dennis; von Kries, Rüdiger; Radon, Katja

2008-09-01

The use of mobile phone telecommunication has increased in recent years. In parallel, there is growing concern about possible adverse health effects of cellular phone networks. We used personal dosimetry to investigate the association between exposure to mobile phone frequencies and well-being in adults. A random population-based sample of 329 adults living in four different Bavarian towns was assembled for the study. Using a dosimeter (ESM-140 Maschek Electronics), we obtained an exposure profile over 24 h for three mobile phone frequency ranges (measurement interval 1 s, limit of determination 0.05 V/m). Exposure levels over waking hours were totalled and expressed as mean percentage of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference level. Each participant reported acute symptoms in a day-long diary. Data on five groups of chronic symptoms and potential confounders were assessed during an interview. The overall exposure to high-frequency electromagnetic fields was markedly below the ICNIRP reference level. We did not find any statistically significant association between the exposure and chronic symptoms or between the exposure and acute symptoms. Larger studies using mobile phone dosimetry are warranted to confirm these findings. Copyright 2008 Wiley-Liss, Inc.

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

PubMed

Ogden, K; Roskopf, M; Scalzetti, E

2012-06-01

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

Effect of fluoroscopic X-ray beam spectrum on air-kerma measurement accuracy: implications for establishing correction coefficients on interventional fluoroscopes with KAP meters.

PubMed

Wunderle, Kevin A; Rakowski, Joseph T; Dong, Frank F

2016-05-08

The first goal of this study was to investigate the accuracy of the displayed reference plane air kerma (Ka,r) or air kerma-area product (Pk,a) over a broad spectrum of X-ray beam qualities on clinically used interventional fluoroscopes incorporating air kerma-area product meters (KAP meters) to measure X-ray output. The second goal was to investigate the accuracy of a correction coefficient (CC) determined at a single beam quality and applied to the measured Ka,r over a broad spectrum of beam qualities. Eleven state-of-the-art interventional fluoroscopes were evaluated, consisting of eight Siemens Artis zee and Artis Q systems and three Philips Allura FD systems. A separate calibrated 60 cc ionization chamber (external chamber) was used to determine the accuracy of the KAP meter over a broad range of clinically used beam qualities. For typical adult beam qualities, applying a single CC deter-mined at 100 kVp with copper (Cu) in the beam resulted in a deviation of < 5% due to beam quality variation. This result indicates that applying a CC determined using The American Association of Physicists in Medicine Task Group 190 protocol or a similar protocol provides very good accuracy as compared to the allowed ± 35% deviation of the KAP meter in this limited beam quality range. For interventional fluoroscopes dedicated to or routinely used to perform pediatric interventions, using a CC established with a low kVp (~ 55-60 kVp) and large amount of Cu filtration (~ 0.6-0.9 mm) may result in greater accuracy as compared to using the 100 kVp values. KAP meter responses indicate that fluoroscope vendors are likely normalizing or otherwise influencing the KAP meter output data. Although this may provide improved accuracy in some instances, there is the potential for large discrete errors to occur, and these errors may be difficult to identify.

Optical dosimetry of radiotherapy beams using Cherenkov radiation: the relationship between light emission and dose.

PubMed

Glaser, Adam K; Zhang, Rongxiao; Gladstone, David J; Pogue, Brian W

2014-07-21

Recent studies have proposed that light emitted by the Cherenkov effect may be used for a number of radiation therapy dosimetry applications. There is a correlation between the captured light and expected dose under certain conditions, yet discrepancies have also been observed and a complete examination of the theoretical differences has not been done. In this study, a fundamental comparison between the Cherenkov emission and absorbed dose was explored for x-ray photons, electrons, and protons using both a theoretical and Monte Carlo-based analysis. Based on the findings of where dose correlates with Cherenkov emission, it was concluded that for x-ray photons the light emission would be optimally suited for narrow beam stereotactic radiation therapy and surgery validation studies, for verification of dynamic intensity-modulated and volumetric modulated arc therapy treatment plans in water tanks, near monoenergetic sources (e.g., Co-60 and brachy therapy sources) and also for entrance and exit surface imaging dosimetry of both narrow and broad beams. For electron use, Cherenkov emission was found to be only suitable for surface dosimetry applications. Finally, for proton dosimetry, there exists a fundamental lack of Cherenkov emission at the Bragg peak, making the technique of little use, although post-irradiation detection of light emission from radioisotopes could prove to be useful.

Occupational exposure to the whole body, extremities and to the eye lens in interventional radiology in Poland, as based on personnel dosimetry records at IFJ PAN

NASA Astrophysics Data System (ADS)

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

2014-11-01

We report results of measurements of Hp(10) from whole body dosimeters (about 53 thousand readouts), of Hp(0.07) from finger ring dosimeters (23 thousand readouts) and of Hp(3) from eye lens dosimeters (100 readouts), issued in the years 2010-12 to over 150 medical departments in Poland which apply X-rays in radiology, interventional radiology (haemodynamic, angiology, cardiac surgery), urology, orthopaedics, electrophysiology or electro-cardiology. In all measurements thermoluminescence detectors (TLD) were used: the well-known standard MTS-N (LiF:Mg, Ti) for whole body and extremity dosimetry, and the high-sensitivity MCP-N (LiF:Mg, Cu, P) for eye lens dosimetry and environmental monitoring. We analysed the data base of the accredited Laboratory of Individual and Environmental Dosimetry (LADIS) at the Institute of Nuclear Physics PAN which offers its dosimetry service to these departments on a regular basis. We found that in the population of radiation workers that studied over the years 2010-2012 in 84%, 87%, and 34% of Hp(10), Hp(0.07) and Hp(3) measurements, respectively, the level of 0.1 mSv/quarter did not exceed, indicating lack of their occupational exposure. In the remaining 16%, 13% and 66% of individual cases, the 0.1 mSv/quarter exceeded, occasionally reaching several hundreds of mSv/quarter.

A radiation quality correction factor k for well-type ionization chambers for the measurement of the reference air kerma rate of (60)Co HDR brachytherapy sources.

PubMed

Schüller, Andreas; Meier, Markus; Selbach, Hans-Joachim; Ankerhold, Ulrike

2015-07-01

The aim of this study was to investigate whether a chamber-type-specific radiation quality correction factor kQ can be determined in order to measure the reference air kerma rate of (60)Co high-dose-rate (HDR) brachytherapy sources with acceptable uncertainty by means of a well-type ionization chamber calibrated for (192)Ir HDR sources. The calibration coefficients of 35 well-type ionization chambers of two different chamber types for radiation fields of (60)Co and (192)Ir HDR brachytherapy sources were determined experimentally. A radiation quality correction factor kQ was determined as the ratio of the calibration coefficients for (60)Co and (192)Ir. The dependence on chamber-to-chamber variations, source-to-source variations, and source strength was investigated. For the PTW Tx33004 (Nucletron source dosimetry system (SDS)) well-type chamber, the type-specific radiation quality correction factor kQ is 1.19. Note that this value is valid for chambers with the serial number, SN ≥ 315 (Nucletron SDS SN ≥ 548) onward only. For the Standard Imaging HDR 1000 Plus well-type chambers, the type-specific correction factor kQ is 1.05. Both kQ values are independent of the source strengths in the complete clinically relevant range. The relative expanded uncertainty (k = 2) of kQ is UkQ = 2.1% for both chamber types. The calibration coefficient of a well-type chamber for radiation fields of (60)Co HDR brachytherapy sources can be calculated from a given calibration coefficient for (192)Ir radiation by using a chamber-type-specific radiation quality correction factor kQ. However, the uncertainty of a (60)Co calibration coefficient calculated via kQ is at least twice as large as that for a direct calibration with a (60)Co source.

Advanced dosimetry systems for the space transport and space station

NASA Technical Reports Server (NTRS)

Wailly, L. F.; Schneider, M. F.; Clark, B. C.

1972-01-01

Advanced dosimetry system concepts are described that will provide automated and instantaneous measurement of dose and particle spectra. Systems are proposed for measuring dose rate from cosmic radiation background to greater than 3600 rads/hr. Charged particle spectrometers, both internal and external to the spacecraft, are described for determining mixed field energy spectra and particle fluxes for both real time onboard and ground-based computer evaluation of the radiation hazard. Automated passive dosimetry systems consisting of thermoluminescent dosimeters and activation techniques are proposed for recording the dose levels for twelve or more crew members. This system will allow automatic onboard readout and data storage of the accumulated dose and can be transmitted to ground after readout or data records recovered with each crew rotation.

a New ENDF/B-VII.0 Based Multigroup Cross-Section Library for Reactor Dosimetry

NASA Astrophysics Data System (ADS)

Alpan, F. A.; Anderson, S. L.

2009-08-01

The latest of the ENDF/B libraries, ENDF/B-VII.0 was released in December 2006. In this paper, the ENDF/B-VII.O evaluations were used in generating a new coupled neutron/gamma multigroup library having the same group structure of VITAMIN-B6, i.e., the 199-neutron, 42-gamma group library. The new library was generated utilizing NJOY99.259 for pre-processing and the AMPX modules for post-processing of cross sections. An ENDF/B-VI.3 based VITAMIN-B6-like library was also generated. The fine-group libraries and the ENDF/B-VI.3 based 47-neutron, 20-gamma group BUGLE-96 library were used with the discrete ordinates code DORT to obtain a three-dimensional synthesized flux distribution from r, r-θ, and r-z models for a standard Westinghouse 3-loop design reactor. Reaction rates were calculated for ex-vessel neutron dosimetry containing 63Cu(n,α)60Co, 46Ti(n,p)46Sc, 54Fe(n,P)54Mn, 58Ni(n,P)58Co, 238U(n,f)137Cs, 237Np(n,f)137Cs, and 59Co(n,γ)60Co (bare and cadmium covered) reactions. Results were compared to measurements. In comparing the 199-neutron, 42-gamma group ENDF/B-VI.3 and ENDF/B-VII.O libraries, it was observed that the ENDF/B-VI.3 based library results were in better agreement with measurements. There is a maximum difference of 7% (for the 63Cu(n,α)60Co reaction rate calculation) between ENDF/B-VI.3 and ENDF/B-VII.O. Differences between ENDF/B-VI.3 and ENDF/B-VII.O libraries are due to 16O, 1H, 90Zr, 91Zr, 92Zr, 238U, and 239Pu evaluations. Both ENDF/B-VI.3 and ENDF/B-VII.O library calculated reaction rates are within 20% of measurement and meet the criterion specified in the U. S. Nuclear Regulatory Commission Regulatory Guide 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence."

TU-D-209-01: Dosimetry of Diagnostic Work Up Mammography

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

Jallow, N; Sechopoulos, I

2016-06-15

Purpose: To investigate patient average glandular dose (AGD) characteristics of diagnostic mammography. Methods: The techniques used to image 14420 patients who received diagnostic work up mammography from October 2008 to December 2014 at one academic hospital were retrospectively collected. The most common diagnostic views and the techniques used for each according to compressed breast thickness were determined. For all techniques, 1st half value layer and air kerma output per tube current-exposure time product were measured; then the incident air kerma for each acquisition was calculated. The values for normalized glandular dose (DgN) were obtained with a validated Monte Carlo simulationmore » of mammographic acquisition. The mono-energetic DgN results were combined according to relative fluence using the TASMICS model to obtain DgN coefficients for each spectrum. The spectral DgN and calculated incident air kerma were used to estimate AGD of patients with breast thickness ranging from 2 to 8 cm. Results: The most common views utilized during diagnostic mammography were magnification craniocaudal (24%), magnification mediolateral (19%), spot craniocaudal (28%), and spot mediolateral oblique (24%). The AGD increased with increasing breast thickness for both the magnification and spot views. The AGD for a 5.5 cm thick breast was approximately 6.8 mGy and 2.2 mGy for the magnification and spot views, respectively. The AGD ranged from 3.6 mGy to 6.8 mGy for the magnification views and from 1.0 mGy to 3.1 mGy for spot views. The difference in AGD between the two magnification views or the two spot views was not significant. Conclusion: These results provide information on breast dose to which screening recalled women are exposed to. In addition to understanding the dose used for common clinical imaging tests, this data could be used when comparing use of mammography for diagnostic workup to other potential modalities, such as breast tomosynthesis and breast CT.« less

Magnetic Fluid Hyperthermia for Bladder Cancer: A Preclinical Dosimetry Study

PubMed Central

Oliveira, Tiago R.; Stauffer, Paul R.; Lee, Chen-Ting; Landon, Chelsea D.; Etienne, Wiguins; Ashcraft, Kathleen A.; McNerny, Katie L.; Mashal, Alireza; Nouls, John; Maccarini, Paolo F.; Beyer, Wayne F.; Inman, Brant; Dewhirst, Mark W.

2014-01-01

Purpose This paper describes a preclinical investigation of the feasibility of thermotherapy treatment of bladder cancer with Magnetic Fluid Hyperthermia (MFH), performed by analyzing the thermal dosimetry of nanoparticle heating in a rat bladder model. Materials and Methods The bladders of twenty-five female rats were instilled with magnetite-based nanoparticles, and hyperthermia was induced using a novel small animal magnetic field applicator (Actium Biosystems, Boulder, CO). We aimed to increase the bladder lumen temperature to 42°C in <10 min and maintain that temperature for 60 min. Temperatures were measured within the bladder lumen and throughout the rat with seven fiberoptic probes (OpSens Technologies, Quebec, Canada). An MRI analysis was used to confirm the effectiveness of the catheterization method to deliver and maintain various nanoparticle volumes within the bladder. Thermal dosimetry measurements recorded the temperature rise of rat tissues for a variety of nanoparticle exposure conditions. Results Thermal dosimetry data demonstrated our ability to raise and control the temperature of rat bladder lumen ≥1°C/min to a steady-state of 42°C with minimal heating of surrounding normal tissues. MRI scans confirmed the homogenous nanoparticle distribution throughout the bladder. Conclusion These data demonstrate that our MFH system with magnetite-based nanoparticles provide well-localized heating of rat bladder lumen with effective control of temperature in the bladder and minimal heating of surrounding tissues. PMID:24050253

RCT: Module 2.04, Dosimetry, Course 8769

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

Hillmer, Kurt T.

This course will introduce the types of instruments used to measure external and internal radiation to people. Dosimetry is the quantitative assessment of radiation received by the human body. Several types of dosimeters are used worldwide. This information is valuable to all radiological control personnel because dosimeters are the only direct method to measure and document personnel radiation exposure and ensure regulatory compliance with applicable limits. This course will cover dosimetry terms, Department of Energy (DOE) limits, Los Alamos National Laboratory (LANL) administrative guidelines, thermoluminescent dosimeters (TLDs), LANL dosimetry, and bioassay assessment methods. This course will prepare the student withmore » the skills necessary for radiological control technician (RCT) qualification by passing quizzes, tests, and the RCT Comprehensive Phase 1, Unit 2 Examination (TEST 27566) and providing in-thefield skills.« less

Clinical impact of (99m)Tc-MAA SPECT/CT-based dosimetry in the radioembolization of liver malignancies with (90)Y-loaded microspheres.

PubMed

Garin, Etienne; Rolland, Yan; Laffont, Sophie; Edeline, Julien

2016-03-01

Radioembolization with (90)Y-loaded microspheres is increasingly used in the treatment of primary and secondary liver cancer. Technetium-99 m macroaggregated albumin (MAA) scintigraphy is used as a surrogate of microsphere distribution to assess lung or digestive shunting prior to therapy, based on tumoral targeting and dosimetry. To date, this has been the sole pre-therapeutic tool available for such evaluation. Several dosimetric approaches have been described using both glass and resin microspheres in hepatocellular carcinoma (HCC) and liver metastasis. Given that each product offers different specific activities and numbers of spheres injected, their radiobiological properties are believed to lightly differ. This paper summarizes and discusses the available studies focused on MAA-based dosimetry, particularly concentrating on potential confounding factors like clinical context, tumor size, cirrhosis, previous or concomitant therapy, and product used. In terms of the impact of tumoral dose in HCC, the results were concordant and a response relationship and tumoral threshold dose was clearly identified, especially in studies using glass microspheres. Tumoral dose has also been found to influence survival. The concept of treatment intensification has recently been introduced, yet despite several studies publishing interesting findings on the tumor dose-metastasis relationship, no consensus has been reached, and further clarification is thus required. Nor has the maximal tolerated dose to the liver been well documented, requiring more accurate evaluation. Lung dose was well described, despite recently identified factors influencing its evaluation, requiring further assessment. Conclusion: MAA SPECT/CT dosimetry is accurate in HCC and can now be used in order to achieve a fully customized approach, including treatment intensification. Yet further studies are warranted for the metastasis setting and evaluating the maximal tolerated liver dose.

Ion-kill dosimetry

NASA Technical Reports Server (NTRS)

Katz, R.; Cucinotta, F. A.; Fromm, M.; Chambaudet, A.

2001-01-01

Unanticipated late effects in neutron and heavy ion therapy, not attributable to overdose, imply a qualitative difference between low and high LET therapy. We identify that difference as 'ion kill', associated with the spectrum of z/beta in the radiation field, whose measurement we label 'ion-kill dosimetry'.

Design of a head phantom produced on a 3D rapid prototyping printer and comparison with a RANDO and 3M lucite head phantom in eye dosimetry applications

NASA Astrophysics Data System (ADS)

Homolka, Peter; Figl, Michael; Wartak, Andreas; Glanzer, Mathias; Dünkelmeyer, Martina; Hojreh, Azadeh; Hummel, Johann

2017-04-01

An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using a photo-cured acrylic resin to best allow tissue equivalence. Thus Hp(3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface. A comparison of dose reduction factors (DRFs) of a common lead glasses model has also been performed. Eye dose per incident air kerma were comparable between all three phantoms (printed phantom: 1.40, standard error (SE) 0.04; RANDO: 1.36, SE 0.03; 3M: 1.37, SE 0.03). Doses to the forehead were identical to eye surface doses for the printed phantom and the RANDO head (ratio 1.00 SE 0.04, and 0.99 SE 0.03, respectively). In the 3M Lucite skull phantom dose on the forehead was 15% lower than dose to the eyes attributable to phantom properties. DRF of a sport frame style leaded glasses model with 0.75 mm lead equivalence measured were 6.8 SE 0.5, 9.3 SE 0.4 and 10.5 SE 0.5 for the RANDO head, the printed phantom, and the 3M Lucite head phantom, respectively, for frontal irradiation. A comparison of doses measured in 3 mm depth and on the surface of the eyes in the printed phantom revealed no difference larger than standard errors from TLD dosimetry. 3D printing offers an interesting opportunity for phantom design with increasing potential as printers allowing combinations of tissue substitutes will become available. Variations between phantoms may provide a useful indication of uncertainty budgets when using phantom measurements to estimate individual personnel doses.

Design of a head phantom produced on a 3D rapid prototyping printer and comparison with a RANDO and 3M lucite head phantom in eye dosimetry applications.

PubMed

Homolka, Peter; Figl, Michael; Wartak, Andreas; Glanzer, Mathias; Dünkelmeyer, Martina; Hojreh, Azadeh; Hummel, Johann

2017-04-21

An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using a photo-cured acrylic resin to best allow tissue equivalence. Thus H p (3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface. A comparison of dose reduction factors (DRFs) of a common lead glasses model has also been performed. Eye dose per incident air kerma were comparable between all three phantoms (printed phantom: 1.40, standard error (SE) 0.04; RANDO: 1.36, SE 0.03; 3M: 1.37, SE 0.03). Doses to the forehead were identical to eye surface doses for the printed phantom and the RANDO head (ratio 1.00 SE 0.04, and 0.99 SE 0.03, respectively). In the 3M Lucite skull phantom dose on the forehead was 15% lower than dose to the eyes attributable to phantom properties. DRF of a sport frame style leaded glasses model with 0.75 mm lead equivalence measured were 6.8 SE 0.5, 9.3 SE 0.4 and 10.5 SE 0.5 for the RANDO head, the printed phantom, and the 3M Lucite head phantom, respectively, for frontal irradiation. A comparison of doses measured in 3 mm depth and on the surface of the eyes in the printed phantom revealed no difference larger than standard errors from TLD dosimetry. 3D printing offers an interesting opportunity for phantom design with increasing potential as printers allowing combinations of tissue substitutes will become available. Variations between phantoms may provide a useful indication of uncertainty budgets when using phantom measurements to estimate individual personnel doses.

Technical considerations for implementation of x-ray CT polymer gel dosimetry.

PubMed

Hilts, M; Jirasek, A; Duzenli, C

2005-04-21

Gel dosimetry is the most promising 3D dosimetry technique in current radiation therapy practice. X-ray CT has been shown to be a feasible method of reading out polymer gel dosimeters and, with the high accessibility of CT scanners to cancer hospitals, presents an exciting possibility for clinical implementation of gel dosimetry. In this study we report on technical considerations for implementation of x-ray CT polymer gel dosimetry. Specifically phantom design, CT imaging methods, imaging time requirements and gel dose response are investigated. Where possible, recommendations are made for optimizing parameters to enhance system performance. The dose resolution achievable with an optimized system is calculated given voxel size and imaging time constraints. Results are compared with MRI and optical CT polymer gel dosimetry results available in the literature.

Dosimetry-based treatment for Graves' disease.

PubMed

Hyer, Steve L; Pratt, Brenda; Gray, Matthew; Chittenden, Sarah; Du, Yong; Harmer, Clive L; Flux, Glenn D

2018-06-01

The aim of this retrospective study was to assess the long-term outcome of a personalized dosimetry approach in Graves' disease aiming to render patients euthyroid from a planned thyroid absorbed dose of 60 Gy. A total of 284 patients with Graves' disease were followed prospectively following administration of radioiodine calculated to deliver an absorbed dose of 60 Gy. Patients with cardiac disease were excluded. Outcomes were analysed at yearly intervals for up to 10 years with a median follow-up of 37.5 months. A single radioiodine administration was sufficient to render a patient either euthyroid or hypothyroid in 175 (62%) patients, the remainder requiring further radioiodine. The median radioactivity required to deliver 60 Gy was 77 MBq. Less than 2% patients required 400-600 MBq, the standard activity administered in many centres. In the cohort receiving a single administration, 38, 32 and 26% were euthyroid on no specific thyroid medication at 3, 5 and 10 years, respectively. Larger thyroid volumes were associated with the need for further therapy. The presence of nodules on ultrasonography did not adversely affect treatment outcome. A personalized dosimetric approach delayed the long-term onset of hypothyroidism in 26% of patients. This was achieved using much lower administered activities than currently recommended. Future studies will aim to identify those patients who would benefit most from this approach.

Dosimetry of 64Cu-DOTA-AE105, a PET tracer for uPAR imaging.

PubMed

Persson, Morten; El Ali, Henrik H; Binderup, Tina; Pfeifer, Andreas; Madsen, Jacob; Rasmussen, Palle; Kjaer, Andreas

2014-03-01

(64)Cu-DOTA-AE105 is a novel positron emission tomography (PET) tracer specific to the human urokinase-type plasminogen activator receptor (uPAR). In preparation of using this tracer in humans, as a new promising method to distinguish between indolent and aggressive cancers, we have performed PET studies in mice to evaluate the in vivo biodistribution and estimate human dosimetry of (64)Cu-DOTA-AE105. Five mice received iv tail injection of (64)Cu-DOTA-AE105 and were PET/CT scanned 1, 4.5 and 22 h post injection. Volume-of-interest (VOI) were manually drawn on the following organs: heart, lung, liver, kidney, spleen, intestine, muscle, bone and bladder. The activity concentrations in the mentioned organs [%ID/g] were used for the dosimetry calculation. The %ID/g of each organ at 1, 4.5 and 22 h was scaled to human value based on a difference between organ and body weights. The scaled values were then exported to OLINDA software for computation of the human absorbed doses. The residence times as well as effective dose equivalent for male and female could be obtained for each organ. To validate this approach, of human projection using mouse data, five mice received iv tail injection of another (64)Cu-DOTA peptide-based tracer, (64)Cu-DOTA-TATE, and underwent same procedure as just described. The human dosimetry estimates were then compared with observed human dosimetry estimate recently found in a first-in-man study using (64)Cu-DOTA-TATE. Human estimates of (64)Cu-DOTA-AE105 revealed the heart wall to receive the highest dose (0.0918 mSv/MBq) followed by the liver (0.0815 mSv/MBq), All other organs/tissue were estimated to receive doses in the range of 0.02-0.04 mSv/MBq. The mean effective whole-body dose of (64)Cu-DOTA-AE105 was estimated to be 0.0317 mSv/MBq. Relatively good correlation between human predicted and observed dosimetry estimates for (64)Cu-DOTA-TATE was found. Importantly, the effective whole body dose was predicted with very high precision

Comparison of the NIST and BIPM Air-Kerma Standards for Measurements in the Low-Energy X-Ray Range

PubMed Central

Burns, D. T.; Lamperti, P.; O’Brien, M.

1999-01-01

A direct comparison was made between the air-kerma standards used for the measurement of low-energy x rays at the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). The comparison was carried out at the BIPM using the BIPM reference beam qualities in the range from 10 kV to 100 kV. The results show the standards to be in agreement to around 0.5 % at reference beam qualities up to 50 kV and at 100 kV. The result at the 80 kV beam quality is less favorable, with agreement at the 1 % level.

Recent Progress in Electromagnetic Absorption and Dosimetry in Biological Systems.

DTIC Science & Technology

1978-12-21

AEROSPACE M!DICAL RESEARCH LABORATORY NAVAL AIR STATION PENSACOLA, FLORIDA 32508 L4 oj6L I SUMMARY PAGE Ti9(PROSLEM Dosimetry , as a subset of research In...absonce of sound dosimetry design, lacks credibility. This study provides a usable orientation in present and future dosimetric technology through a...leading experiment; while at other times experimental results lead the way. Progress In absorption and dosimetry Is still urderway, and higher degrees

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

PubMed Central

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

2010-01-01

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

Advanced proton beam dosimetry part II: Monte Carlo vs. pencil beam-based planning for lung cancer.

PubMed

Maes, Dominic; Saini, Jatinder; Zeng, Jing; Rengan, Ramesh; Wong, Tony; Bowen, Stephen R

2018-04-01

Proton pencil beam (PB) dose calculation algorithms have limited accuracy within heterogeneous tissues of lung cancer patients, which may be addressed by modern commercial Monte Carlo (MC) algorithms. We investigated clinical pencil beam scanning (PBS) dose differences between PB and MC-based treatment planning for lung cancer patients. With IRB approval, a comparative dosimetric analysis between RayStation MC and PB dose engines was performed on ten patient plans. PBS gantry plans were generated using single-field optimization technique to maintain target coverage under range and setup uncertainties. Dose differences between PB-optimized (PBopt), MC-recalculated (MCrecalc), and MC-optimized (MCopt) plans were recorded for the following region-of-interest metrics: clinical target volume (CTV) V95, CTV homogeneity index (HI), total lung V20, total lung V RX (relative lung volume receiving prescribed dose or higher), and global maximum dose. The impact of PB-based and MC-based planning on robustness to systematic perturbation of range (±3% density) and setup (±3 mm isotropic) was assessed. Pairwise differences in dose parameters were evaluated through non-parametric Friedman and Wilcoxon sign-rank testing. In this ten-patient sample, CTV V95 decreased significantly from 99-100% for PBopt to 77-94% for MCrecalc and recovered to 99-100% for MCopt (P<10 -5 ). The median CTV HI (D95/D5) decreased from 0.98 for PBopt to 0.91 for MCrecalc and increased to 0.95 for MCopt (P<10 -3 ). CTV D95 robustness to range and setup errors improved under MCopt (ΔD95 =-1%) compared to MCrecalc (ΔD95 =-6%, P=0.006). No changes in lung dosimetry were observed for large volumes receiving low to intermediate doses (e.g., V20), while differences between PB-based and MC-based planning were noted for small volumes receiving high doses (e.g., V RX ). Global maximum patient dose increased from 106% for PBopt to 109% for MCrecalc and 112% for MCopt (P<10 -3 ). MC dosimetry revealed a reduction

Advanced proton beam dosimetry part II: Monte Carlo vs. pencil beam-based planning for lung cancer

PubMed Central

Maes, Dominic; Saini, Jatinder; Zeng, Jing; Rengan, Ramesh; Wong, Tony

2018-01-01

Background Proton pencil beam (PB) dose calculation algorithms have limited accuracy within heterogeneous tissues of lung cancer patients, which may be addressed by modern commercial Monte Carlo (MC) algorithms. We investigated clinical pencil beam scanning (PBS) dose differences between PB and MC-based treatment planning for lung cancer patients. Methods With IRB approval, a comparative dosimetric analysis between RayStation MC and PB dose engines was performed on ten patient plans. PBS gantry plans were generated using single-field optimization technique to maintain target coverage under range and setup uncertainties. Dose differences between PB-optimized (PBopt), MC-recalculated (MCrecalc), and MC-optimized (MCopt) plans were recorded for the following region-of-interest metrics: clinical target volume (CTV) V95, CTV homogeneity index (HI), total lung V20, total lung VRX (relative lung volume receiving prescribed dose or higher), and global maximum dose. The impact of PB-based and MC-based planning on robustness to systematic perturbation of range (±3% density) and setup (±3 mm isotropic) was assessed. Pairwise differences in dose parameters were evaluated through non-parametric Friedman and Wilcoxon sign-rank testing. Results In this ten-patient sample, CTV V95 decreased significantly from 99–100% for PBopt to 77–94% for MCrecalc and recovered to 99–100% for MCopt (P<10−5). The median CTV HI (D95/D5) decreased from 0.98 for PBopt to 0.91 for MCrecalc and increased to 0.95 for MCopt (P<10−3). CTV D95 robustness to range and setup errors improved under MCopt (ΔD95 =−1%) compared to MCrecalc (ΔD95 =−6%, P=0.006). No changes in lung dosimetry were observed for large volumes receiving low to intermediate doses (e.g., V20), while differences between PB-based and MC-based planning were noted for small volumes receiving high doses (e.g., VRX). Global maximum patient dose increased from 106% for PBopt to 109% for MCrecalc and 112% for MCopt (P<10−3

Czech results at criticality dosimetry intercomparison 2002.

PubMed

Frantisek, Spurný; Jaroslav, Trousil

2004-01-01

Two criticality dosimetry systems were tested by Czech participants during the intercomparison held in Valduc, France, June 2002. The first consisted of the thermoluminescent detectors (TLDs) (Al-P glasses) and Si-diodes as passive neutron dosemeters. Second, it was studied to what extent the individual dosemeters used in the Czech routine personal dosimetry service can give a reliable estimation of criticality accident exposure. It was found that the first system furnishes quite reliable estimation of accidental doses. For routine individual dosimetry system, no important problems were encountered in the case of photon dosemeters (TLDs, film badge). For etched track detectors in contact with the 232Th or 235U-Al alloy, the track density saturation for the spark counting method limits the upper dose at approximately 1 Gy for neutrons with the energy >1 MeV.

Optically stimulated luminescence (OSL) dosimetry in medicine.

PubMed

Yukihara, E G; McKeever, S W S

2008-10-21

This paper reviews fundamental and practical aspects of optically stimulated luminescence (OSL) dosimetry pertaining to applications in medicine, having particularly in mind new researchers and medical physicists interested in gaining familiarity with the field. A basic phenomenological model for OSL is presented and the key processes affecting the outcome of an OSL measurement are discussed. Practical aspects discussed include stimulation modalities (continuous-wave OSL, pulsed OSL and linear modulation OSL), basic experimental setup, available OSL readers, optical fiber systems and basic properties of available OSL dosimeters. Finally, results from the recent literature on applications of OSL in radiotherapy, radiodiagnostics and heavy charged particle dosimetry are discussed in light of the theoretical and practical framework presented in this review. Open questions and future challenges in OSL dosimetry are highlighted as a guide to the research needed to further advance the field.

Online dosimetry for temoporfin-mediated interstitial photodynamic therapy using the canine prostate as model

NASA Astrophysics Data System (ADS)

Swartling, Johannes; Höglund, Odd V.; Hansson, Kerstin; Södersten, Fredrik; Axelsson, Johan; Lagerstedt, Anne-Sofie

2016-02-01

Online light dosimetry with real-time feedback was applied for temoporfin-mediated interstitial photodynamic therapy (PDT) of dog prostate. The aim was to investigate the performance of online dosimetry by studying the correlation between light dose plans and the tissue response, i.e., extent of induced tissue necrosis and damage to surrounding organs at risk. Light-dose planning software provided dose plans, including light source positions and light doses, based on ultrasound images. A laser instrument provided therapeutic light and dosimetric measurements. The procedure was designed to closely emulate the procedure for whole-prostate PDT in humans with prostate cancer. Nine healthy dogs were subjected to the procedure according to a light-dose escalation plan. About 0.15 mg/kg temoporfin was administered 72 h before the procedure. The results of the procedure were assessed by magnetic resonance imaging, and gross pathology and histopathology of excised tissue. Light dose planning and online dosimetry clearly resulted in more focused effect and less damage to surrounding tissue than interstitial PDT without dosimetry. A light energy dose-response relationship was established where the threshold dose to induce prostate gland necrosis was estimated from 20 to 30 J/cm2.

DRDC Ottawa Participation in the SILENE Accident Dosimetry Intercomparison Exercise. June 10-21, 2002

DTIC Science & Technology

2002-11-01

of CaF2:Mn and A120 3 TLDs for gamma-ray dosimetry ). In addition, DRDC Ottawa has recently substantially expanded its efforts in radiation dosimetry ...use of any real- time electronic dosimeter. Foils have long been proposed and used for criticality dosimetry (as well as for general monitoring of...ray Dosimetry DRDC Ottawa offers a number (over five) of various thermoluminescence dosimetry ( TLD ) systems. The choice of any particular TLD depends

MIRD Pamphlet No. 23: Quantitative SPECT for Patient-Specific 3-Dimensional Dosimetry in Internal Radionuclide Therapy

PubMed Central

Dewaraja, Yuni K.; Frey, Eric C.; Sgouros, George; Brill, A. Bertrand; Roberson, Peter; Zanzonico, Pat B.; Ljungberg, Michael

2012-01-01

In internal radionuclide therapy, a growing interest in voxel-level estimates of tissue-absorbed dose has been driven by the desire to report radiobiologic quantities that account for the biologic consequences of both spatial and temporal nonuniformities in these dose estimates. This report presents an overview of 3-dimensional SPECT methods and requirements for internal dosimetry at both regional and voxel levels. Combined SPECT/CT image-based methods are emphasized, because the CT-derived anatomic information allows one to address multiple technical factors that affect SPECT quantification while facilitating the patient-specific voxel-level dosimetry calculation itself. SPECT imaging and reconstruction techniques for quantification in radionuclide therapy are not necessarily the same as those designed to optimize diagnostic imaging quality. The current overview is intended as an introduction to an upcoming series of MIRD pamphlets with detailed radionuclide-specific recommendations intended to provide best-practice SPECT quantification–based guidance for radionuclide dosimetry. PMID:22743252

Comparison of intraoperative dosimetric implant representation with postimplant dosimetry in patients receiving prostate brachytherapy.

PubMed

Stone, Nelson N; Hong, Suzanne; Lo, Yeh-Chi; Howard, Victor; Stock, Richard G

2003-01-01

To compare the results of intraoperative dosimetry with those of CT-based postimplant dosimetry in patients undergoing prostate seed implantation. Seventy-seven patients with T1-T3 prostate cancer received an ultrasound-guided permanent seed implant (36 received (125)I, 7 (103)Pd, and 34 a partial (103)Pd implant plus external beam radiation therapy). The implantation was augmented with an intraoperative dosimetric planning system. After the peripheral needles were placed, 5-mm axial images were acquired into the treatment planning system. Soft tissue structures (prostate, urethra, and rectum) were contoured, and exact needle positions were registered. Seeds were placed with an applicator, and their positions were entered into the planning system. The dose distributions for the implant were calculated after interior needle and seed placement. Postimplant dosimetry was performed 1 month later on the basis of CT imaging. Prostate and urethral doses were compared, by using paired t tests, for the real-time dosimetry in the operating room (OR) and the postimplant dosimetry. The mean preimplant prostate volume was 39.8 cm(3), the postneedle planning volume was 41.5 cm(3) (p<0.001), and the 1-month CT volume was 43.6 cm(3) (p<0.001). The mean difference between the OR dose received by 90% of the prostate (D(90)) and the CT D(90) was 3.4% (95% confidence interval, 2.5-6.6%; p=0.034). The mean dose to 30% of the urethra was 120% of prescription in the OR and 138% on CT. The mean difference was 18% (95% confidence interval, 13-24%; p<0.001). Although small differences exist between the OR and CT dosimetry results, these data suggest that this intraoperative implant dosimetric representation system provides a close match to the actual delivered doses. These data support the use of this system to modify the implant during surgery to achieve more consistent dosimetry results.

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the IST-LPSR, Portugal and the BIPM in 60Co gamma radiation

NASA Astrophysics Data System (ADS)

Kessler, C.; Burns, D.; Cardoso, J.

2018-01-01

A comparison of the standards for air kerma of the Instituto Superior Técnico, Laboratório de Proteção e Segurança Radiológica (IST-LPSR), Portugal and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in December 2015. The comparison result, evaluated as a ratio of the IST-LPSR and the BIPM standards for air kerma, is 1.0026 with a combined standard uncertainty of 1.7 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 1.1 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable 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).

MO-B-BRB-03: 3D Dosimetry in the Clinic: Validating Special Techniques

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

Juang, T.

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

MO-B-BRB-01: 3D Dosimetry in the Clinic: Background and Motivation

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

Schreiner, L.

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

Multichannel film dosimetry with nonuniformity correction.

PubMed

Micke, Andre; Lewis, David F; Yu, Xiang

2011-05-01

A new method to evaluate radiochromic film dosimetry data scanned in multiple color channels is presented. This work was undertaken to demonstrate that the multichannel method is fundamentally superior to the traditional single channel method. The multichannel method allows for the separation and removal of the nondose-dependent portions of a film image leaving a residual image that is dependent only on absorbed dose. Radiochromic films were exposed to 10 x 10 cm radiation fields (Co-60 and 6 MV) at doses up to about 300 cGy. The films were scanned in red-blue-green (RGB) format on a flatbed color scanner and measured to build calibration tables relating the absorbed dose to the response of the film in each of the color channels. Film images were converted to dose maps using two methods. The first method used the response from a single color channel and the second method used the response from all three color channels. The multichannel method allows for the separation of the scanned signal into one part that is dose-dependent and another part that is dose-independent and enables the correction of a variety of disturbances in the digitized image including nonuniformities in the active coating on the radiochromic film as well as scanner related artifacts. The fundamental mathematics of the two methods is described and the dose maps calculated from film images using the two methods are compared and analyzed. The multichannel dosimetry method was shown to be an effective way to separate out non-dose-dependent abnormalities from radiochromic dosimetry film images. The process was shown to remove disturbances in the scanned images caused by nonhomogeneity of the radiochromic film and artifacts caused by the scanner and to improve the integrity of the dose information. Multichannel dosimetry also reduces random noise in the dose images and mitigates scanner-related artifacts such as lateral position dependence. In providing an ability to calculate dose maps from data in

Ionization chamber-based reference dosimetry of intensity modulated radiation beams.

PubMed

Bouchard, Hugo; Seuntjens, Jan

2004-09-01

The present paper addresses reference dose measurements using thimble ionization chambers for quality assurance in IMRT fields. In these radiation fields, detector fluence perturbation effects invalidate the application of open-field dosimetry protocol data for the derivation of absorbed dose to water from ionization chamber measurements. We define a correction factor C(Q)IMRT to correct the absorbed dose to water calibration coefficient N(D, w)Q for fluence perturbation effects in individual segments of an IMRT delivery and developed a calculation method to evaluate the factor. The method consists of precalculating, using accurate Monte Carlo techniques, ionization chamber, type-dependent cavity air dose, and in-phantom dose to water at the reference point for zero-width pencil beams as a function of position of the pencil beams impinging on the phantom surface. These precalculated kernels are convolved with the IMRT fluence distribution to arrive at the dose-to-water-dose-to-cavity air ratio [D(a)w (IMRT)] for IMRT fields and with a 10x10 cm2 open-field fluence to arrive at the same ratio D(a)w (Q) for the 10x10 cm2 reference field. The correction factor C(Q)IMRT is then calculated as the ratio of D(a)w (IMRT) and D(a)w (Q). The calculation method was experimentally validated and the magnitude of chamber correction factors in reference dose measurements in single static and dynamic IMRT fields was studied. The results show that, for thimble-type ionization chambers the correction factor in a single, realistic dynamic IMRT field can be of the order of 10% or more. We therefore propose that for accurate reference dosimetry of complete n-beam IMRT deliveries, ionization chamber fluence perturbation correction factors must explicitly be taken into account.

Analysis of dosimetry from the H.B. Robinson unit 2 pressure vessel benchmark using RAPTOR-M3G and ALPAN

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

Fischer, G.A.

2011-07-01

Document available in abstract form only, full text of document follows: The dosimetry from the H. B. Robinson Unit 2 Pressure Vessel Benchmark is analyzed with a suite of Westinghouse-developed codes and data libraries. The radiation transport from the reactor core to the surveillance capsule and ex-vessel locations is performed by RAPTOR-M3G, a parallel deterministic radiation transport code that calculates high-resolution neutron flux information in three dimensions. The cross-section library used in this analysis is the ALPAN library, an Evaluated Nuclear Data File (ENDF)/B-VII.0-based library designed for reactor dosimetry and fluence analysis applications. Dosimetry is evaluated with the industry-standard SNLRMLmore » reactor dosimetry cross-section data library. (authors)« less

Magnetomotive Optical Coherence Elastography for Magnetic Hyperthermia Dosimetry Based on Dynamic Tissue Biomechanics

PubMed Central

Huang, Pin-Chieh; Pande, Paritosh; Ahmad, Adeel; Marjanovic, Marina; Spillman, Darold R.; Odintsov, Boris; Boppart, Stephen A.

2016-01-01

Magnetic nanoparticles (MNPs) have been used in many diagnostic and therapeutic biomedical applications over the past few decades to enhance imaging contrast, steer drugs to targets, and treat tumors via hyperthermia. Optical coherence tomography (OCT) is an optical biomedical imaging modality that relies on the detection of backscattered light to generate high-resolution cross-sectional images of biological tissue. MNPs have been utilized as imaging contrast and perturbative mechanical agents in OCT in techniques called magnetomotive OCT (MM-OCT) and magnetomotive elastography (MM-OCE), respectively. MNPs have also been independently used for magnetic hyperthermia treatments, enabling therapeutic functions such as killing tumor cells. It is well known that the localized tissue heating during hyperthermia treatments result in a change in the biomechanical properties of the tissue. Therefore, we propose a novel dosimetric technique for hyperthermia treatment based on the viscoelasticity change detected by MM-OCE, further enabling the theranostic function of MNPs. In this paper, we first review the basic principles and applications of MM-OCT, MM-OCE, and magnetic hyperthermia, and present new preliminary results supporting the concept of MM-OCE-based hyperthermia dosimetry. PMID:28163565

Radiation dosimetry for quality control of food preservation and disinfestation

NASA Astrophysics Data System (ADS)

McLaughlin, W. L.; Miller, A.; Uribe, R. M.

In the use of x and gamma rays and scanned electron beams to extend the shelf life of food by delay of sprouting and ripening, killing of microbes, and control of insect population, quality assurance is provided by standardized radiation dosimetry. By strategic placement of calibrated dosimeters that are sufficiently stable and reproducible, it is possible to monitor minimum and maximum radiation absorbed dose levels and dose uniformity for a given processed foodstuff. The dosimetry procedure is especially important in the commisioning of a process and in making adjustments of process parameters (e.g. conveyor speed) to meet changes that occur in product and source parameters (e.g. bulk density and radiation spectrum). Routine dosimetry methods and certain corrections of dosimetry data may be selected for the radiations used in typical food processes.

OSL properties of three commonly available salt brands in India for its use in accident dosimetry

NASA Astrophysics Data System (ADS)

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

2018-03-01

Thermally stimulated luminescence (TL) and Optically Stimulated Luminescence (OSL) characterization of three commonly available salt brands in India were undertaken for their application in accident dosimetry. The investigations showed that the luminescence properties differed to some extent with that reported in literature. Dosimetric properties of these salt samples showed that these can be useful in accident dosimetry. Based on the sensitization and fading behaviour of the samples a Single Aliquot Regenerative (SAR) protocol has been proposed for dose estimation.

Model-based versus specific dosimetry in diagnostic context: Comparison of three dosimetric approaches

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

Marcatili, S., E-mail: sara.marcatili@inserm.fr; Villoing, D.; Mauxion, T.

Purpose: The dosimetric assessment of novel radiotracers represents a legal requirement in most countries. While the techniques for the computation of internal absorbed dose in a therapeutic context have made huge progresses in recent years, in a diagnostic scenario the absorbed dose is usually extracted from model-based lookup tables, most often derived from International Commission on Radiological Protection (ICRP) or Medical Internal Radiation Dose (MIRD) Committee models. The level of approximation introduced by these models may impact the resulting dosimetry. The aim of this work is to establish whether a more refined approach to dosimetry can be implemented in nuclearmore » medicine diagnostics, by analyzing a specific case. Methods: The authors calculated absorbed doses to various organs in six healthy volunteers administered with flutemetamol ({sup 18}F) injection. Each patient underwent from 8 to 10 whole body 3D PET/CT scans. This dataset was analyzed using a Monte Carlo (MC) application developed in-house using the toolkit GATE that is capable to take into account patient-specific anatomy and radiotracer distribution at the voxel level. They compared the absorbed doses obtained with GATE to those calculated with two commercially available software: OLINDA/EXM and STRATOS implementing a dose voxel kernel convolution approach. Results: Absorbed doses calculated with GATE were higher than those calculated with OLINDA. The average ratio between GATE absorbed doses and OLINDA’s was 1.38 ± 0.34 σ (from 0.93 to 2.23). The discrepancy was particularly high for the thyroid, with an average GATE/OLINDA ratio of 1.97 ± 0.83 σ for the six patients. Differences between STRATOS and GATE were found to be higher. The average ratio between GATE and STRATOS absorbed doses was 2.51 ± 1.21 σ (from 1.09 to 6.06). Conclusions: This study demonstrates how the choice of the absorbed dose calculation algorithm may introduce a bias when gamma radiations are of

A reference skeletal dosimetry model for an adult male radionuclide therapy patient based on three-dimensional imaging and paired-image radiation transport

NASA Astrophysics Data System (ADS)

Shah, Amish P.

The need for improved patient-specificity of skeletal dose estimates is widely recognized in radionuclide therapy. Current clinical models for marrow dose are based on skeletal mass estimates from a variety of sources and linear chord-length distributions that do not account for particle escape into cortical bone. To predict marrow dose, these clinical models use a scheme that requires separate calculations of cumulated activity and radionuclide S values. Selection of an appropriate S value is generally limited to one of only three sources, all of which use as input the trabecular microstructure of an individual measured 25 years ago, and the tissue mass derived from different individuals measured 75 years ago. Our study proposed a new modeling approach to marrow dosimetry---the Paired Image Radiation Transport (PIRT) model---that properly accounts for both the trabecular microstructure and the cortical macrostructure of each skeletal site in a reference male radionuclide patient. The PIRT model, as applied within EGSnrc, requires two sets of input geometry: (1) an infinite voxel array of segmented microimages of the spongiosa acquired via microCT; and (2) a segmented ex-vivo CT image of the bone site macrostructure defining both the spongiosa (marrow, endosteum, and trabeculae) and the cortical bone cortex. Our study also proposed revising reference skeletal dosimetry models for the adult male cancer patient. Skeletal site-specific radionuclide S values were obtained for a 66-year-old male reference patient. The derivation for total skeletal S values were unique in that the necessary skeletal mass and electron dosimetry calculations were formulated from the same source bone site over the entire skeleton. We conclude that paired-image radiation-transport techniques provide an adoptable method by which the intricate, anisotropic trabecular microstructure of the skeletal site; and the physical size and shape of the bone can be handled together, for improved

SU-F-T-283: A Novel Device to Enable Portal Dosimetry for Flattening Filter Free Beams

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

Faught, A; Wu, Q; Adamson, J

Purpose: Varian’s electronic portal imaging device (EPID) based portal dosimetry tool is a popular and effective means of performing IMRT QA. EPIDs for older models of the TrueBeam accelerator utilize a 40cmx30cm Image Detection Unit (IDU) that saturates at the center for standard source to imager distances with high dose rate flattening filter free (FFF) beams. This makes portal dosimetry not possible and an alternative means of IMRT QA necessary. We developed a filter that would attenuate the beam to a dose rate measureable by the IDU for portal dosimetry IMRT QA. Methods: Multipurpose 304 stainless steel plates were placedmore » on an accessory tray to attenuate the beam. Profiles of an open field measured on the IDU were acquired with varying number of plates to assess the thickness needed to reduce the maximum dose rates of 6XFFF and 10XFFF beams to measurable levels. A new portal dose image prediction (PDIP) model was commissioned based on open field measurements with plates in position, and a modified beam profile was input to portal dosimetry calibration at the console to empirically correct for attenuation and scatter. The portal dosimetry tool was used to assess agreement between predicted and measured doses for open 25×25cm{sup 2} fields and intensity modulated fields using 6XFFF and 10XFFF beams. Results: Thicknesses of 2.5cm and 3.8cm of steel were required to reduce the highest dose rates to a measureable level for 6XFFF and 10XFFF, respectively. Gamma analysis using a 3%/3mm relative criterion with the filter in place and using the new PDIP model resulted in 98.2% and 93.6% of pixels passing while intensity modulated fields showed passing rates of 98.2% and 99.0%. Conclusion: Use of the filter allows for portal dosimetry to be used for IMRT QA of FFF plans in place of purchasing a second option for IMRT QA.« less

Energy-based dosimetry of low-energy, photon-emitting brachytherapy sources

NASA Astrophysics Data System (ADS)

Malin, Martha J.

Model-based dose calculation algorithms (MBDCAs) for low-energy, photon-emitting brachytherapy sources have advanced to the point where the algorithms may be used in clinical practice. Before these algorithms can be used, a methodology must be established to verify the accuracy of the source models used by the algorithms. Additionally, the source strength metric for these algorithms must be established. This work explored the feasibility of verifying the source models used by MBDCAs by measuring the differential photon fluence emitted from the encapsulation of the source. The measured fluence could be compared to that modeled by the algorithm to validate the source model. This work examined how the differential photon fluence varied with position and angle of emission from the source, and the resolution that these measurements would require for dose computations to be accurate to within 1.5%. Both the spatial and angular resolution requirements were determined. The techniques used to determine the resolution required for measurements of the differential photon fluence were applied to determine why dose-rate constants determined using a spectroscopic technique disagreed with those computed using Monte Carlo techniques. The discrepancy between the two techniques had been previously published, but the cause of the discrepancy was not known. This work determined the impact that some of the assumptions used by the spectroscopic technique had on the accuracy of the calculation. The assumption of isotropic emission was found to cause the largest discrepancy in the spectroscopic dose-rate constant. Finally, this work improved the instrumentation used to measure the rate at which energy leaves the encapsulation of a brachytherapy source. This quantity is called emitted power (EP), and is presented as a possible source strength metric for MBDCAs. A calorimeter that measured EP was designed and built. The theoretical framework that the calorimeter relied upon to measure EP

[Measurement of the air kerma using dosimeters embedded in an acrylic phantom in interventional radiology.].

PubMed

Kawabe, Atsushi; Shibuya, Koichi; Takeda, Yoshihiro

2006-01-01

Interventional radiology procedure guidelines and a measurement manual (IVR guidelines) have been published for the maintenance of interventional equipment with an objective of avoiding serious radiation-induced skin injuries. In the IVR guidelines, the positioning of a dosimeter at the interventional reference point is determined, whereas placement of a phantom is not specified. Therefore, the phantom is placed at any convenient location between the dosimeter and image intensifier. The space around the dosimeter reduces detection of scattered radiation. In this study, dosimeters (consisting of a parallel plate ionization chamber, glass dosimeter and OSL dosimeter) were embedded in the phantom surface to detected scattered radiation accurately. As a result, when dosimeters were embedded in the phantom surface, the air kerma was increased compared with that when dosimeters were placed on the phantom. This suggested that embedded dosimeters were able to detect scattered radiation from the phantom.

Protocols for the dosimetry of high-energy photon and electron beams: a comparison of the IAEA TRS-398 and previous international Codes of Practice

NASA Astrophysics Data System (ADS)

Andreo, Pedro; Saiful Huq, M.; Westermark, Mathias; Song, Haijun; Tilikidis, Aris; DeWerd, Larry; Shortt, Ken

2002-09-01

A new international Code of Practice for radiotherapy dosimetry co-sponsored by several international organizations has been published by the IAEA, TRS-398. It is based on standards of absorbed dose to water, whereas previous protocols (TRS-381 and TRS-277) were based on air kerma standards. To estimate the changes in beam calibration caused by the introduction of TRS-398, a detailed experimental comparison of the dose determination in reference conditions in high-energy photon and electron beams has been made using the different IAEA protocols. A summary of the formulation and reference conditions in the various Codes of Practice, as well as of their basic data, is presented first. Accurate measurements have been made in 25 photon and electron beams from 10 clinical accelerators using 12 different cylindrical and plane-parallel chambers, and dose ratios under different conditions of TRS-398 to the other protocols determined. A strict step-by-step checklist was followed by the two participating clinical institutions to ascertain that the resulting calculations agreed within tenths of a per cent. The maximum differences found between TRS-398 and the previous Codes of Practice TRS-277 (2nd edn) and TRS-381 are of the order of 1.5-2.0%. TRS-398 yields absorbed doses larger than the previous protocols, around 1.0% for photons (TRS-277) and for electrons (TRS-381 and TRS-277) when plane-parallel chambers are cross-calibrated. For the Markus chamber, results show a very large variation, although a fortuitous cancellation of the old stopping powers with the ND,w/NK ratios makes the overall discrepancy between TRS-398 and TRS-277 in this case smaller than for well-guarded plane-parallel chambers. Chambers of the Roos-type with a 60Co ND,w calibration yield the maximum discrepancy in absorbed dose, which varies between 1.0% and 1.5% for TRS-381 and between 1.5% and 2.0% for TRS-277. Photon beam calibrations using directly measured or calculated TPR20,10 from a percentage

SU-E-T-675: Remote Dosimetry with a Novel PRESAGE Formulation

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

Mein, S; Juang, T; Malcolm, J

2015-06-15

Purpose: 3D-gel dosimetry provides high-resolution treatment validation; however, scanners aren’t widely available. In remote dosimetry, dosimeters are shipped out from a central base institution to a remote site for irradiation, then shipped back for scanning and analysis, affording a convenient service for treatment validation to institutions lacking the necessary equipment and resources. Previous works demonstrated the high-resolution performance and temporal stability of PRESAGE. Here the newest formulation is investigated for remote dosimetry use. Methods: A new formulation of PRESAGE was created with the aim of improved color stability post irradiation. Dose sensitivity was determined by irradiating cuvettes on a Varianmore » Linac (6MV) from 0–15Gy and measuring change in optical density at 633nm. Sensitivity readings were tracked over time in a temperature control study to determine long-term stability. A large volume study was performed to evaluate the accuracy for remote dosimetry. A 1kg dosimeter was pre-scanned, irradiated on-site with an 8Gy 4field box treatment, post-scanned and shipped to Princess Margaret Hospital for remote reading on an identical scanner. Results: Dose sensitivities ranged from 0.0194–0.0295 ΔOD/(Gy*cm)—similar to previous formulations. Post-irradiated cuvettes stored at 10°C retained 100% initial sensitivity over 5 days and 98.6% over 10 weeks while cuvettes stored at room temperature fell to 95.8% after 5 days and 37.4% after 10 weeks. The immediate and 5-day scans of the 4field box dosimeter data was reconstructed, registered to the corresponding eclipse dose-distribution, and compared with analytical tools in CERR. Immediate and 5-day scans looked visually similar. Line profiles revealed close agreement aside from a slight elevation in dose at the edge in the 5-day readout. Conclusion: The remote dosimetry formulation exhibits excellent temporal stability in small volumes. While immediate and 5-day readout scans of

Improving the accuracy of ionization chamber dosimetry in small megavoltage x-ray fields

NASA Astrophysics Data System (ADS)

McNiven, Andrea L.

The dosimetry of small x-ray fields is difficult, but important, in many radiation therapy delivery methods. The accuracy of ion chambers for small field applications, however, is limited due to the relatively large size of the chamber with respect to the field size, leading to partial volume effects, lateral electronic disequilibrium and calibration difficulties. The goal of this dissertation was to investigate the use of ionization chambers for the purpose of dosimetry in small megavoltage photon beams with the aim of improving clinical dose measurements in stereotactic radiotherapy and helical tomotherapy. A new method for the direct determination of the sensitive volume of small-volume ion chambers using micro computed tomography (muCT) was investigated using four nominally identical small-volume (0.56 cm3) cylindrical ion chambers. Agreement between their measured relative volume and ionization measurements (within 2%) demonstrated the feasibility of volume determination through muCT. Cavity-gas calibration coefficients were also determined, demonstrating the promise for accurate ion chamber calibration based partially on muCT. The accuracy of relative dose factor measurements in 6MV stereotactic x-ray fields (5 to 40mm diameter) was investigated using a set of prototype plane-parallel ionization chambers (diameters of 2, 4, 10 and 20mm). Chamber and field size specific correction factors ( CSFQ ), that account for perturbation of the secondary electron fluence, were calculated using Monte Carlo simulation methods (BEAM/EGSnrc simulations). These correction factors (e.g. CSFQ = 1.76 (2mm chamber, 5mm field) allow for accurate relative dose factor (RDF) measurement when applied to ionization readings, under conditions of electronic disequilibrium. With respect to the dosimetry of helical tomotherapy, a novel application of the ion chambers was developed to characterize the fan beam size and effective dose rate. Characterization was based on an adaptation of the

Skeletal dosimetry based on µCT images of trabecular bone: update and comparisons

NASA Astrophysics Data System (ADS)

Kramer, R.; Cassola, V. F.; Vieira, J. W.; Khoury, H. J.; de Oliveira Lira, C. A. B.; Robson Brown, K.

2012-06-01

Two skeletal dosimetry methods using µCT images of human bone have recently been developed: the paired-image radiation transport (PIRT) model introduced by researchers at the University of Florida (UF) in the US and the systematic-periodic cluster (SPC) method developed by researchers at the Federal University of Pernambuco in Brazil. Both methods use µCT images of trabecular bone (TB) to model spongiosa regions of human bones containing marrow cavities segmented into soft tissue volumes of active marrow (AM), trabecular inactive marrow and the bone endosteum (BE), which is a 50 µm thick layer of marrow on all TB surfaces and on cortical bone surfaces next to TB as well as inside the medullary cavities. With respect to the radiation absorbed dose, the AM and the BE are sensitive soft tissues for the induction of leukaemia and bone cancer, respectively. The two methods differ mainly with respect to the number of bone sites and the size of the µCT images used in Monte Carlo calculations and they apply different methods to simulate exposure from radiation sources located outside the skeleton. The PIRT method calculates dosimetric quantities in isolated human bones while the SPC method uses human bones embedded in the body of a phantom which contains all relevant organs and soft tissues. Consequently, the SPC method calculates absorbed dose to the AM and to the BE from particles emitted by radionuclides concentrated in organs or from radiation sources located outside the human body in one calculation step. In order to allow for similar calculations of AM and BE absorbed doses using the PIRT method, the so-called dose response functions (DRFs) have been developed based on absorbed fractions (AFs) of energy for electrons isotropically emitted in skeletal tissues. The DRFs can be used to transform the photon fluence in homogeneous spongiosa regions into absorbed dose to AM and BE. This paper will compare AM and BE AFs of energy from electrons emitted in skeletal

In vitro dosimetry of agglomerates

NASA Astrophysics Data System (ADS)

Hirsch, V.; Kinnear, C.; Rodriguez-Lorenzo, L.; Monnier, C. A.; Rothen-Rutishauser, B.; Balog, S.; Petri-Fink, A.

2014-06-01

Agglomeration of nanoparticles in biological fluids is a pervasive phenomenon that leads to difficulty in the interpretation of results from in vitro exposure, primarily due to differing particokinetics of agglomerates to nanoparticles. Therefore, well-defined small agglomerates were designed that possessed different particokinetic profiles, and their cellular uptake was compared to a computational model of dosimetry. The approach used here paves the way for a better understanding of the impact of agglomeration on the nanoparticle-cell interaction.Agglomeration of nanoparticles in biological fluids is a pervasive phenomenon that leads to difficulty in the interpretation of results from in vitro exposure, primarily due to differing particokinetics of agglomerates to nanoparticles. Therefore, well-defined small agglomerates were designed that possessed different particokinetic profiles, and their cellular uptake was compared to a computational model of dosimetry. The approach used here paves the way for a better understanding of the impact of agglomeration on the nanoparticle-cell interaction. Electronic supplementary information (ESI) available: ITC data for tiopronin/Au-NP interactions, agglomeration kinetics at different pHs for tiopronin-coated Au-NPs, UV-Vis spectra in water, PBS and DMEM and temporal correlation functions for single Au-NPs and corresponding agglomerates, calculation of diffusion and sedimentation parameters, modelling of relative cell uptake based on the ISDD model and cytotoxicity of single Au-NPs and their agglomerates, and synthesis and cell uptake of large spherical Au-NPs. See DOI: 10.1039/c4nr00460d

SU-F-J-100: Standardized Biodistribution Template for Nuclear Medicine Dosimetry Collection and Reporting

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

Kesner, A; Poli, G; Beykan, S

Purpose: As the field of Nuclear Medicine moves forward with efforts to integrate radiation dosimetry into clinical practice we can identify the challenge posed by the lack of standardized dose calculation methods and protocols. All personalized internal dosimetry is derived by projecting biodistribution measurements into dosimetry calculations. In an effort to standardize organization of data and its reporting, we have developed, as a sequel to the EANM recommendation of “Good Dosimetry Reporting”, a freely available biodistribution template, which can be used to create a common point of reference for dosimetry data. It can be disseminated, interpreted, and used for methodmore » development widely across the field. Methods: A generalized biodistribution template was built in a comma delineated format (.csv) to be completed by users performing biodistribution measurements. The template is available for free download. The download site includes instructions and other usage details on the template. Results: This is a new resource developed for the community. It is our hope that users will consider integrating it into their dosimetry operations. Having biodistribution data available and easily accessible for all patients processed is a strategy for organizing large amounts of information. It may enable users to create their own databases that can be analyzed for multiple aspects of dosimetry operations. Furthermore, it enables population data to easily be reprocessed using different dosimetry methodologies. With respect to dosimetry-related research and publications, the biodistribution template can be included as supplementary material, and will allow others in the community to better compare calculations and results achieved. Conclusion: As dosimetry in nuclear medicine become more routinely applied in clinical applications, we, as a field, need to develop the infrastructure for handling large amounts of data. Our organ level biodistribution template can be

A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: Report of AAPM Task Group No. 138 and GEC-ESTRO

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

DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.

2011-02-15

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinicmore » for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Europeen de Curietherapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be

A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: Report of AAPM Task Group No. 138 and GEC-ESTRO

PubMed Central

DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Mitch, Michael G.; Rivard, Mark J.; Stump, Kurt E.; Thomadsen, Bruce R.; Venselaar, Jack L. M.

2011-01-01

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie–European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used

A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: report of AAPM Task Group No. 138 and GEC-ESTRO.

PubMed

DeWerd, Larry A; Ibbott, Geoffrey S; Meigooni, Ali S; Mitch, Michael G; Rivard, Mark J; Stump, Kurt E; Thomadsen, Bruce R; Venselaar, Jack L M

2011-02-01

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as

A national dosimetry audit for stereotactic ablative radiotherapy in lung.

PubMed

Distefano, Gail; Lee, Jonny; Jafari, Shakardokht; Gouldstone, Clare; Baker, Colin; Mayles, Helen; Clark, Catharine H

2017-03-01

A UK national dosimetry audit was carried out to assess the accuracy of Stereotactic Ablative Body Radiotherapy (SABR) lung treatment delivery. This mail-based audit used an anthropomorphic thorax phantom containing nine alanine pellets positioned in the lung region for dosimetry, as well as EBT3 film in the axial plane for isodose comparison. Centres used their local planning protocol/technique, creating 27 SABR plans. A range of delivery techniques including conformal, volumetric modulated arc therapy (VMAT) and Cyberknife (CK) were used with six different calculation algorithms (collapsed cone, superposition, pencil-beam (PB), AAA, Acuros and Monte Carlo). The mean difference between measured and calculated dose (excluding PB results) was 0.4±1.4% for alanine and 1.4±3.4% for film. PB differences were -6.1% and -12.9% respectively. The median of the absolute maximum isodose-to-isodose distances was 3mm (-6mm to 7mm) and 5mm (-10mm to +19mm) for the 100% and 50% isodose lines respectively. Alanine and film is an effective combination for verifying dosimetric and geometric accuracy. There were some differences across dose algorithms, and geometric accuracy was better for VMAT and CK compared with conformal techniques. The alanine dosimetry results showed that planned and delivered doses were within ±3.0% for 25/27 SABR plans. Copyright © 2017 Elsevier B.V. All rights reserved.

New image-processing and noise-reduction software reduces radiation dose during complex endovascular procedures.

PubMed

Kirkwood, Melissa L; Guild, Jeffrey B; Arbique, Gary M; Tsai, Shirling; Modrall, J Gregory; Anderson, Jon A; Rectenwald, John; Timaran, Carlos

2016-11-01

A new proprietary image-processing system known as AlluraClarity, developed by Philips Healthcare (Best, The Netherlands) for radiation-based interventional procedures, claims to lower radiation dose while preserving image quality using noise-reduction algorithms. This study determined whether the surgeon and patient radiation dose during complex endovascular procedures (CEPs) is decreased after the implementation of this new operating system. Radiation dose to operators, procedure type, reference air kerma, kerma area product, and patient body mass index were recorded during CEPs on two Philips Allura FD 20 fluoroscopy systems with and without Clarity. Operator dose during CEPs was measured using optically stimulable, luminescent nanoDot (Landauer Inc, Glenwood, Ill) detectors placed outside the lead apron at the left upper chest position. nanoDots were read using a microStar ii (Landauer Inc) medical dosimetry system. For the CEPs in the Clarity group, the radiation dose to surgeons was also measured by the DoseAware (Philips Healthcare) personal dosimetry system. Side-by-side measurements of DoseAware and nanoDots allowed for cross-calibration between systems. Operator effective dose was determined using a modified Niklason algorithm. To control for patient size and case complexity, the average fluoroscopy dose rate and the dose per radiographic frame were adjusted for body mass index differences and then compared between the groups with and without Clarity by procedure. Additional factors, for example, physician practice patterns, that may have affected operator dose were inferred by comparing the ratio of the operator dose to procedural kerma area product with and without Clarity. A one-sided Wilcoxon rank sum test was used to compare groups for radiation doses, reference air kermas, and operating practices for each procedure type. The analysis included 234 CEPs; 95 performed without Clarity and 139 with Clarity. Practice patterns of operators during

The Future of Medical Dosimetry

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

Adams, Robert D., E-mail: robert_adams@med.unc.edu

2015-07-01

The world of health care delivery is becoming increasingly complex. The purpose of this manuscript is to analyze current metrics and analytically predict future practices and principles of medical dosimetry. The results indicate five potential areas precipitating change factors: a) evolutionary and revolutionary thinking processes, b) social factors, c) economic factors, d) political factors, and e) technological factors. Outcomes indicate that significant changes will occur in the job structure and content of being a practicing medical dosimetrist. Discussion indicates potential variables that can occur within each process and change factor and how the predicted outcomes can deviate from normative values.more » Finally, based on predicted outcomes, future opportunities for medical dosimetrists are given.« less

SU-E-T-87: A TG-100 Approach for Quality Improvement of Associated Dosimetry Equipment

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

Manger, R; Pawlicki, T; Kim, G

2015-06-15

Purpose: Dosimetry protocols devote so much time to the discussion of ionization chamber choice, use and performance that is easy to forget about the importance of the associated dosimetry equipment (ADE) in radiation dosimetry - barometer, thermometer, electrometer, phantoms, triaxial cables, etc. Improper use and inaccuracy of these devices may significantly affect the accuracy of radiation dosimetry. The purpose of this study is to evaluate the risk factors in the monthly output dosimetry procedure and recommend corrective actions using a TG-100 approach. Methods: A failure mode and effects analysis (FMEA) of the monthly linac output check procedure was performed tomore » determine which steps and failure modes carried the greatest risk. In addition, a fault tree analysis (FTA) was performed to expand the initial list of failure modes making sure that none were overlooked. After determining the failure modes with the highest risk priority numbers (RPNs), 11 physicists were asked to score corrective actions based on their ease of implementation and potential impact. The results were aggregated into an impact map to determine the implementable corrective actions. Results: Three of the top five failure modes were related to the thermometer and barometer. The two highest RPN-ranked failure modes were related to barometric pressure inaccuracy due to their high lack-of-detectability scores. Six corrective actions were proposed to address barometric pressure inaccuracy, and the survey results found the following two corrective actions to be implementable: 1) send the barometer for recalibration at a calibration laboratory and 2) check the barometer accuracy against the local airport and correct for elevation. Conclusion: An FMEA on monthly output measurements displayed the importance of ADE for accurate radiation dosimetry. When brainstorming for corrective actions, an impact map is helpful for visualizing the overall impact versus the ease of implementation.« less

Application for internal dosimetry using biokinetic distribution of photons based on nuclear medicine images.

PubMed

Leal Neto, Viriato; Vieira, José Wilson; Lima, Fernando Roberto de Andrade

2014-01-01

This article presents a way to obtain estimates of dose in patients submitted to radiotherapy with basis on the analysis of regions of interest on nuclear medicine images. A software called DoRadIo (Dosimetria das Radiações Ionizantes [Ionizing Radiation Dosimetry]) was developed to receive information about source organs and target organs, generating graphical and numerical results. The nuclear medicine images utilized in the present study were obtained from catalogs provided by medical physicists. The simulations were performed with computational exposure models consisting of voxel phantoms coupled with the Monte Carlo EGSnrc code. The software was developed with the Microsoft Visual Studio 2010 Service Pack and the project template Windows Presentation Foundation for C# programming language. With the mentioned tools, the authors obtained the file for optimization of Monte Carlo simulations using the EGSnrc; organization and compaction of dosimetry results with all radioactive sources; selection of regions of interest; evaluation of grayscale intensity in regions of interest; the file of weighted sources; and, finally, all the charts and numerical results. The user interface may be adapted for use in clinical nuclear medicine as a computer-aided tool to estimate the administered activity.

An interlaboratory comparison of dosimetry for a multi-institutional radiobiological research project: Observations, problems, solutions and lessons learned.

PubMed

Seed, Thomas M; Xiao, Shiyun; Manley, Nancy; Nikolich-Zugich, Janko; Pugh, Jason; Van den Brink, Marcel; Hirabayashi, Yoko; Yasutomo, Koji; Iwama, Atsushi; Koyasu, Shigeo; Shterev, Ivo; Sempowski, Gregory; Macchiarini, Francesca; Nakachi, Kei; Kunugi, Keith C; Hammer, Clifford G; Dewerd, Lawrence A

2016-01-01

An interlaboratory comparison of radiation dosimetry was conducted to determine the accuracy of doses being used experimentally for animal exposures within a large multi-institutional research project. The background and approach to this effort are described and discussed in terms of basic findings, problems and solutions. Dosimetry tests were carried out utilizing optically stimulated luminescence (OSL) dosimeters embedded midline into mouse carcasses and thermal luminescence dosimeters (TLD) embedded midline into acrylic phantoms. The effort demonstrated that the majority (4/7) of the laboratories was able to deliver sufficiently accurate exposures having maximum dosing errors of ≤5%. Comparable rates of 'dosimetric compliance' were noted between OSL- and TLD-based tests. Data analysis showed a highly linear relationship between 'measured' and 'target' doses, with errors falling largely between 0 and 20%. Outliers were most notable for OSL-based tests, while multiple tests by 'non-compliant' laboratories using orthovoltage X-rays contributed heavily to the wide variation in dosing errors. For the dosimetrically non-compliant laboratories, the relatively high rates of dosing errors were problematic, potentially compromising the quality of ongoing radiobiological research. This dosimetry effort proved to be instructive in establishing rigorous reviews of basic dosimetry protocols ensuring that dosing errors were minimized.

Dosimetry in Thermal Neutron Irradiation Facility at BMRR

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

Hu, J. P.; Holden, N. E.; Reciniello, R. N.

Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; includingmore » (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D 2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4 - 7

Effect of respiratory motion on internal radiation dosimetry

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

Xie, Tianwu; Zaidi, Habib, E-mail: habib.zaidi@hcuge.ch; Geneva Neuroscience Center, Geneva University, Geneva CH-1205

anatomical model provides more accurate internal radiation dosimetry estimates for the lungs and abdominal organs based on realistic modeling of respiratory motion. This work also contributes to a better understanding of model-induced uncertainties in internal radiation dosimetry.« less

Dosimetry in Thermal Neutron Irradiation Facility at BMRR

NASA Astrophysics Data System (ADS)

Hu, J.-P.; Holden, N. E.; Reciniello, R. N.

2016-02-01

Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4-7% lower than

Advances in EPA’s Rapid Exposure and Dosimetry Project (Interagency Alternatives Assessment Webinar)

EPA Science Inventory

Estimates of human and ecological exposures are required as critical input to risk-based prioritization and screening of chemicals. The CSS Rapid Exposure and Dosimetry project seeks to develop the data, tools, and evaluation approaches required to generate rapid and scientifical...

Canadian Cytogenetic Emergency network (CEN) for biological dosimetry following radiological/nuclear accidents.

PubMed

Miller, Susan M; Ferrarotto, Catherine L; Vlahovich, Slavica; Wilkins, Ruth C; Boreham, Douglas R; Dolling, Jo-Anna

2007-07-01

To test the ability of the cytogenetic emergency network (CEN) of laboratories, currently under development across Canada, to provide rapid biological dosimetry using the dicentric assay for triage assessment, that could be implemented in the event of a large-scale radiation/nuclear emergency. A workshop was held in May 2004 in Toronto, Canada, to introduce the concept of CEN and recruit clinical cytogenetic laboratories at hospitals across the country. Slides were prepared for dicentric assay analysis following in vitro irradiation of blood to a range of gamma-ray doses. A minimum of 50 metaphases per slide were analyzed by 41 people at 22 different laboratories to estimate the exposure level. Dose estimates were calculated based on a dose response curve generated at Health Canada. There were a total of 104 dose estimates and 96 (92.3%) of them fell within the expected range using triage scoring criteria. Half of the laboratories analyzed 50 metaphases in dosimetry. When this network is fully operational, it will be the first of its kind in Canada able to respond to radiological/nuclear emergencies by providing triage quality biological dosimetry for a large number of samples. This network represents an alternate expansion of existing international emergency biological dosimetry cytogenetic networks.

ISDD: A computational model of particle sedimentation, diffusion and target cell dosimetry for in vitro toxicity studies

PubMed Central

2010-01-01

Background The difficulty of directly measuring cellular dose is a significant obstacle to application of target tissue dosimetry for nanoparticle and microparticle toxicity assessment, particularly for in vitro systems. As a consequence, the target tissue paradigm for dosimetry and hazard assessment of nanoparticles has largely been ignored in favor of using metrics of exposure (e.g. μg particle/mL culture medium, particle surface area/mL, particle number/mL). We have developed a computational model of solution particokinetics (sedimentation, diffusion) and dosimetry for non-interacting spherical particles and their agglomerates in monolayer cell culture systems. Particle transport to cells is calculated by simultaneous solution of Stokes Law (sedimentation) and the Stokes-Einstein equation (diffusion). Results The In vitro Sedimentation, Diffusion and Dosimetry model (ISDD) was tested against measured transport rates or cellular doses for multiple sizes of polystyrene spheres (20-1100 nm), 35 nm amorphous silica, and large agglomerates of 30 nm iron oxide particles. Overall, without adjusting any parameters, model predicted cellular doses were in close agreement with the experimental data, differing from as little as 5% to as much as three-fold, but in most cases approximately two-fold, within the limits of the accuracy of the measurement systems. Applying the model, we generalize the effects of particle size, particle density, agglomeration state and agglomerate characteristics on target cell dosimetry in vitro. Conclusions Our results confirm our hypothesis that for liquid-based in vitro systems, the dose-rates and target cell doses for all particles are not equal; they can vary significantly, in direct contrast to the assumption of dose-equivalency implicit in the use of mass-based media concentrations as metrics of exposure for dose-response assessment. The difference between equivalent nominal media concentration exposures on a μg/mL basis and target cell

Modelling and Dosimetry for Alpha-Particle Therapy

PubMed Central

Sgouros, George; Hobbs, Robert F.; Song, Hong

2015-01-01

As a consequence of the high potency and short range of alpha-particles, radiopharmaceutical therapy with alpha-particle emitting radionuclides is a promising treatment approach that is under active pre-clinical and clinical investigation. To understand and predict the biological effects of alpha-particle radiopharmaceuticals, dosimetry is required at the micro or multi-cellular scale level. At such a scale, highly non-uniform irradiation of the target volume may be expected and the utility of a single absorbed dose value to predict biological effects comes into question. It is not currently possible to measure the pharmacokinetic input required for micro scale dosimetry in humans. Accordingly, pre-clinical studies are required to provide the pharmacokinetic data for dosimetry calculations. The translation of animal data to the human requires a pharmacokinetic model that links macro- and micro-scale pharmacokinetics thereby enabling the extrapolation of micro-scale kinetics from macroscopic measurements. These considerations along with a discussion of the appropriate physical quantity and related units for alpha-particle radiopharmaceutical therapy are examined in this review. PMID:22201712

Hanford Internal Dosimetry Project manual. Revision 1

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

Carbaugh, E.H.; Bihl, D.E.; MacLellan, J.A.

1994-07-01

This document describes the Hanford Internal Dosimetry Project, as it is administered by Pacific Northwest Laboratory (PNL) in support of the US Department of Energy and its Hanford contractors. Project services include administrating the bioassay monitoring program, evaluating and documenting assessment of potential intakes and internal dose, ensuring that analytical laboratories conform to requirements, selecting and applying appropriate models and procedures for evaluating radionuclide deposition and the resulting dose, and technically guiding and supporting Hanford contractors in matters regarding internal dosimetry. Specific chapters deal with the following subjects: practices of the project, including interpretation of applicable DOE Orders, regulations, andmore » guidance into criteria for assessment, documentation, and reporting of doses; assessment of internal dose, including summary explanations of when and how assessments are performed; recording and reporting practices for internal dose; selection of workers for bioassay monitoring and establishment of type and frequency of bioassay measurements; capability and scheduling of bioassay monitoring services; recommended dosimetry response to potential internal exposure incidents; quality control and quality assurance provisions of the program.« less

Criticality accident dosimetry with ESR spectroscopy.

PubMed

d'Errico, F; Fattibene, P; Onori, S; Pantaloni, M

1996-01-01

The suitability of the ESR alanine and sugar detectors for criticality accident dosimetry was experimentally investigated during an intercomparison of dosimetry techniques. Tests were performed irradiating detectors both free-in-air and on-phantom during controlled critcality excursions at the SILENE reactor in Valduc, France. Several grays of absorbed dose were imparted in neutron gamma-ray fields of various relative intensities and spectral distributions. Analysed results confirmed the potential of these systems which can immediately provide an acute dose assessment with an average underestimate of 30%in the various fields. This performance allows for the screening of severely exposed individuals and meets the IAEA recommendations on the early estimate of accident absorbed doses.

Verification of Dosimetry Measurements with Timepix Pixel Detectors for Space Applications

NASA Technical Reports Server (NTRS)

Kroupa, M.; Pinsky, L. S.; Idarraga-Munoz, J.; Hoang, S. M.; Semones, E.; Bahadori, A.; Stoffle, N.; Rios, R.; Vykydal, Z.; Jakubek, J.;

Interferometric optical online dosimetry for selective retina treatment (SRT)

NASA Astrophysics Data System (ADS)

Stoehr, Hardo; Ptaszynski, Lars; Fritz, Andreas; Brinkmann, Ralf

2007-07-01

Selective retina treatment (SRT) is a new laser based method to treat retinal diseases associated with disorders of the retinal pigment epithelium (RPE). Applying microsecond laser pulses tissue damage spatially confined to the retinal pigment epithelium (RPE) is achieved. The RPE cell damage is caused by transient microbubbles emerging at the strongly absorbing melanin granules inside the RPE cells. Due to the spatial confinement to the RPE the photoreceptors can be spared and vision can be maintained in the treated retinal areas. A drawback for effective clinical SRT is that the laser induced lesions are ophthalmoscopically invisible. Therefore, a real-time feedback system for dosimetry is necessary in order to avoid undertreatment or unwanted collateral damage to the adjacent tissue. We develop a dosimetry system which uses optical interferometry for the detection of the transient microbubbles. The system is based on an optical fiber interferometer operated with a laser diode at 830nm. We present current results obtained with a laser slit lamp using porcine RPE explants in vitro and complete porcine eye globes ex vivo. The RPE cell damage is determined by Calcein fluorescence viability assays. With a threshold criterium for RPE cell death derived from the measured interferometric signal transients good agreement with the results of the viability assays is achieved.

Dosimetry for audit and clinical trials: challenges and requirements

NASA Astrophysics Data System (ADS)

Kron, T.; Haworth, A.; Williams, I.

2013-06-01

Many important dosimetry audit networks for radiotherapy have their roots in clinical trial quality assurance (QA). In both scenarios it is essential to test two issues: does the treatment plan conform with the clinical requirements and is the plan a reasonable representation of what is actually delivered to a patient throughout their course of treatment. Part of a sound quality program would be an external audit of these issues with verification of the equivalence of plan and treatment typically referred to as a dosimetry audit. The increasing complexity of radiotherapy planning and delivery makes audits challenging. While verification of absolute dose delivered at a reference point was the standard of external dosimetry audits two decades ago this is often deemed inadequate for verification of treatment approaches such as Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT). As such, most dosimetry audit networks have successfully introduced more complex tests of dose delivery using anthropomorphic phantoms that can be imaged, planned and treated as a patient would. The new challenge is to adapt this approach to ever more diversified radiotherapy procedures with image guided/adaptive radiotherapy, motion management and brachytherapy being the focus of current research.

A survey of current in vivo radiotherapy dosimetry practice.

PubMed

Edwards, C R; Grieveson, M H; Mountford, P J; Rolfe, P

1997-03-01

A questionnaire was sent out to 57 radiotherapy physics departments in the United Kingdom to determine the type of dosemeters used for in vivo measurements inside and outside X-ray treatment fields, and whether any correction is made for energy dependence when the dose to critical organs outside the main beam is estimated. 44 responses were received. 11 centres used a semi-conductor for central axis dosimetry compared with only two centres which used thermoluminescent dosimetry (TLD). 37 centres carried out dosimetry measurements outside the main beam; 25 centres used TLD and 12 centres used a semi-conductor detector. Of the 16 centres measuring the dose at both sites. 11 used a semi-conductor for the central axis measurement, but only four of those 11 changed to TLD for critical organ dosimetry despite the latter's lower variation in energy response. None of the centres stated that they made a correction for the variation in detector energy response when making measurements outside the main beam, indicating a need for a more detailed evaluation of the energy response of these detectors and the energy spectra outside the main beam.

Macroscopic to Microscopic Scales of Particulate Dosimetry: From Source to Fate in the Body

EPA Science Inventory

Additional perspective with regards to particle dosimetry is achieved by exploring dosimetry across a range of scales from macroscopic to microscopic in scope. Typically, one thinks of dosimetry as what happens when a particle is inhaled, where it is deposited, and how it is clea...

Innovation and the future of advanced dosimetry: 2D to 5D

NASA Astrophysics Data System (ADS)

Oldham, Mark

2017-05-01

Recent years have witnessed a remarkable evolution in the techniques, capabilities and applications of 3D dosimetry. Initially the goal was simple: to innovate new techniques capable of comprehensively measuring and verifying exquisitely intricate dose distributions from a paradigm changing emerging new therapy, IMRT. Basic questions emerged: how well were treatment planning systems modelling the complex delivery, and how could treatments be verified for safe use on patients? Since that time, equally significant leaps of innovation have continued in the technology of treatment delivery. In addition, clinical practice has been transformed by the addition of on-board imaging capabilities, which tend to hypo-fractionation strategies and margin reduction. The net result is a high stakes treatment setting where the clinical morbidity of any unintended treatment deviation is exacerbated by the combination of highly conformal dose distributions given with reduced margins with fractionation regimens unfriendly to healthy tissue. Not surprisingly this scenario is replete with challenges and opportunities for new and improved dosimetry systems. In particular tremendous interest exists in comprehensive 3D dosimetry systems, and systems that can resolve the dose in moving structures (4D) and even in deforming structures (5D). Despite significant progress in the capability of multi-dimensional dosimetry systems, it is striking that true 3D dosimetry systems are today largely found in academic institutions or specialist clinics. The reasons will be explored. We will highlight innovations occurring both in treatment delivery and in advanced dosimetry methods designed to verify them, and explore current and future opportunities for advanced dosimetry tools in clinical practice and translational research.

Applicability of Topaz Composites to Electron Dosimetry

NASA Astrophysics Data System (ADS)

Bomfim, K. S.; Souza, D. N.

2010-11-01

Thermoluminescent dosimetric topaz properties have been investigated and the results have shown that this mineral presents characteristics of a good dosimeter mainly in doses evaluation in radiotherapy with photons beams in radiotherapy. Typical applications of thermoluminescent dosimeters in radiotherapy are: in vivo dosimetry on patients (either as a routine quality assurance procedure or for dose monitoring in special cases); verification of treatment techniques; dosimetry audits; and comparisons among hospitals. The mean aim of this work was to evaluate the efficiency of topaz-Teflon pellets as thermoluminescent dosimeters in high-energy electron beams used to radiotherapy. Topaz-Teflon pellets were used as TLD.

MO-B-BRB-02: 3D Dosimetry in the Clinic: IMRT Technique Validation in Sweden

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

Ceberg, S.

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by themore » development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data

EPR/PTFE dosimetry for test reactor environments

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

Vehar, D.W.; Griffin, P.J.; Quirk, T.J.

2011-07-01

The use of Electron Paramagnetic Resonance (EPR) spectroscopy with materials such as alanine is well established as a technique for measurement of ionizing radiation absorbed dose in photon and electron fields such as Co-60, high-energy bremsstrahlung and electron-beam fields [1]. In fact, EPR/Alanine dosimetry has become a routine transfer standard for national standards bodies such as NIST and NPL. In 1992 the Radiation Metrology Laboratory (RML) at Sandia National Laboratories implemented EPR/Alanine capabilities for use in routine and calibration activities at its Co-60 and pulsed-power facilities. At that time it also investigated the usefulness of the system for measurement ofmore » absorbed dose in the mixed neutron/photon environments of reactors such as the Sandia Pulsed Reactor and the Annular Core Research Reactor used for hardness testing of electronics. The RML concluded that the neutron response of alanine was a sufficiently high fraction of the overall dosimeter response that the resulting uncertainties in the photon dose would be unacceptably large for silicon-device testing. However, it also suggested that non-hydrogenous materials such as polytetrafluoroethylene (PTFE) would exhibit smaller neutron response and might be useful in mixed environments. Preliminary research with PTFE in photon environments indicated considerable promise, but further development was not pursued at that time. Because of renewed interest in absorbed dose measurements that could better define the individual contributions of photon and neutron components to the overall dose delivered to a test object, the RML has re-initiated the development of an EPR/PTFE dosimetry system. This effort consists of three stages: 1) Identification of PTFE materials that may be suitable for dosimetry applications. It was speculated that the inconsistency of EPR signatures in the earlier samples may have been due to variability in PTFE manufacturing processes. 2) Characterization of

Hanford Internal Dosimetry Program Manual, PNL-MA-552

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

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2003-10-10

This manual is a guide to the services provided by the Hanford Internal Dosimetry Program (IDP). It describes the roles of and relationships between the IDP and site contractors, and provides recommendations and guidance for consideration in implementing bioassay monitoring and internal dosimetry elements of radiation protection programs. Guidance includes identifying conditions under which workers should be placed on bioassay programs, types, descritptions, and capabilities of measurements, suggested routine bioassay programs, limitations on services, and practices for recording and reporting results.

Monte Carlo simulations to replace film dosimetry in IMRT verification.

PubMed

Goetzfried, Thomas; Rickhey, Mark; Treutwein, Marius; Koelbl, Oliver; Bogner, Ludwig

2011-01-01

Patient-specific verification of intensity-modulated radiation therapy (IMRT) plans can be done by dosimetric measurements or by independent dose or monitor unit calculations. The aim of this study was the clinical evaluation of IMRT verification based on a fast Monte Carlo (MC) program with regard to possible benefits compared to commonly used film dosimetry. 25 head-and-neck IMRT plans were recalculated by a pencil beam based treatment planning system (TPS) using an appropriate quality assurance (QA) phantom. All plans were verified both by film and diode dosimetry and compared to MC simulations. The irradiated films, the results of diode measurements and the computed dose distributions were evaluated, and the data were compared on the basis of gamma maps and dose-difference histograms. Average deviations in the high-dose region between diode measurements and point dose calculations performed with the TPS and MC program were 0.7 ± 2.7% and 1.2 ± 3.1%, respectively. For film measurements, the mean gamma values with 3% dose difference and 3mm distance-to-agreement were 0.74 ± 0.28 (TPS as reference) with dose deviations up to 10%. Corresponding values were significantly reduced to 0.34 ± 0.09 for MC dose calculation. The total time needed for both verification procedures is comparable, however, by far less labor intensive in the case of MC simulations. The presented study showed that independent dose calculation verification of IMRT plans with a fast MC program has the potential to eclipse film dosimetry more and more in the near future. Thus, the linac-specific QA part will necessarily become more important. In combination with MC simulations and due to the simple set-up, point-dose measurements for dosimetric plausibility checks are recommended at least in the IMRT introduction phase. Copyright © 2010. Published by Elsevier GmbH.

Film dosimetry using a smart device camera: a feasibility study for point dose measurements

NASA Astrophysics Data System (ADS)

Aland, Trent; Jhala, Ekta; Kairn, Tanya; Trapp, Jamie

2017-10-01

In this work, a methodology for using a smartphone camera, in conjunction with a light-tight box operating in reflective transmission mode, is investigated as a proof of concept for use as a film dosimetry system. An imaging system was designed to allow the camera of a smartphone to be used as a pseudo densitometer. Ten pieces of Gafchromic EBT3 film were irradiated to doses up to 16.89 Gy and used to evaluate the effects of reproducibility and orientation, as well as the ability to create an accurate dose response curve for the smartphone based dosimetry system, using all three colour channels. Results were compared to a flatbed scanner system. Overall uncertainty was found to be best for the red channel with an uncertainty of 2.4% identified for film irradiated to 2.5 Gy and digitised using the smartphone system. This proof of concept exercise showed that although uncertainties still exceed a flatbed scanner system, the smartphone system may be useful for providing point dose measurements in situations where conventional flatbed scanners (or other dosimetry systems) are unavailable or unaffordable.

Film dosimetry using a smart device camera: a feasibility study for point dose measurements.

PubMed

Aland, Trent; Jhala, Ekta; Kairn, Tanya; Trapp, Jamie

2017-10-03

In this work, a methodology for using a smartphone camera, in conjunction with a light-tight box operating in reflective transmission mode, is investigated as a proof of concept for use as a film dosimetry system. An imaging system was designed to allow the camera of a smartphone to be used as a pseudo densitometer. Ten pieces of Gafchromic EBT3 film were irradiated to doses up to 16.89 Gy and used to evaluate the effects of reproducibility and orientation, as well as the ability to create an accurate dose response curve for the smartphone based dosimetry system, using all three colour channels. Results were compared to a flatbed scanner system. Overall uncertainty was found to be best for the red channel with an uncertainty of 2.4% identified for film irradiated to 2.5 Gy and digitised using the smartphone system. This proof of concept exercise showed that although uncertainties still exceed a flatbed scanner system, the smartphone system may be useful for providing point dose measurements in situations where conventional flatbed scanners (or other dosimetry systems) are unavailable or unaffordable.

Interfractional trend analysis of dose differences based on 2D transit portal dosimetry

NASA Astrophysics Data System (ADS)

Persoon, L. C. G. G.; Nijsten, S. M. J. J. G.; Wilbrink, F. J.; Podesta, M.; Snaith, J. A. D.; Lustberg, T.; van Elmpt, W. J. C.; van Gils, F.; Verhaegen, F.

2012-10-01

Dose delivery of a radiotherapy treatment can be influenced by a number of factors. It has been demonstrated that the electronic portal imaging device (EPID) is valuable for transit portal dosimetry verification. Patient related dose differences can emerge at any time during treatment and can be categorized in two types: (1) systematic—appearing repeatedly, (2) random—appearing sporadically during treatment. The aim of this study is to investigate how systematic and random information appears in 2D transit dose distributions measured in the EPID plane over the entire course of a treatment and how this information can be used to examine interfractional trends, building toward a methodology to support adaptive radiotherapy. To create a trend overview of the interfractional changes in transit dose, the predicted portal dose for the different beams is compared to a measured portal dose using a γ evaluation. For each beam of the delivered fraction, information is extracted from the γ images to differentiate systematic from random dose delivery errors. From the systematic differences of a fraction for a projected anatomical structures, several metrics are extracted like percentage pixels with |γ| > 1. We demonstrate for four example cases the trends and dose difference causes which can be detected with this method. Two sample prostate cases show the occurrence of a random and systematic difference and identify the organ that causes the difference. In a lung cancer case a trend is shown of a rapidly diminishing atelectasis (lung fluid) during the course of treatment, which was detected with this trend analysis method. The final example is a breast cancer case where we show the influence of set-up differences on the 2D transit dose. A method is presented based on 2D portal transit dosimetry to record dose changes throughout the course of treatment, and to allow trend analysis of dose discrepancies. We show in example cases that this method can identify the causes of

Development and dosimetry of a small animal lung irradiation platform

PubMed Central

McGurk, Ross; Hadley, Caroline; Jackson, Isabel L.; Vujaskovic, Zeljko

2015-01-01

Advances in large scale screening of medical counter measures for radiation-induced normal tissue toxicity are currently hampered by animal irradiation paradigms that are both inefficient and highly variable among institutions. Here, we introduce a novel high-throughput small animal irradiation platform for use in orthovoltage small animal irradiators. We used radiochromic film and metal oxide semiconductor field effect transistor detectors to examine several parameters, including 2D field uniformity, dose rate consistency, and shielding transmission. We posit that this setup will improve efficiency of drug screens by allowing for simultaneous, targeted irradiation of multiple animals, improving efficiency within a single institution. Additionally, we suggest that measurement of the described parameters in all centers conducting counter measure studies will improve the translatability of findings among institutions. We also investigated the use of tissue equivalent phantoms in performing dosimetry measurements for small animal irradiation experiments. Though these phantoms are commonly used in dosimetry, we recorded a significant difference in both the entrance and target tissue dose rates between euthanized rats and mice with implanted detectors and the corresponding phantom measurement. This suggests that measurements using these phantoms may not provide accurate dosimetry for in vivo experiments. Based on these measurements, we propose that this small animal irradiation platform can increase the capacity of animal studies by allowing for more efficient animal irradiation. We also suggest that researchers fully characterize the parameters of whatever radiation setup is in use in order to facilitate better comparison among institutions. PMID:23091878

SU-F-T-421: Dosimetry Change During Radiotherapy and Dosimetry Difference for Rigid and Deformed Registration in the Mid-Thoracic Esophageal Carcinoma

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

Tao, C; Liu, T; Chen, J

Purpose: This study aimed to analyze dosimetry changes during radiotherapy for the mid-thoracic esophageal carcinoma, and investigate dosimetry difference between rigid and deformed registration. Methods: Twelve patients with primary middle thoracic esophageal carcinoma were selected randomly. Based on first CT scanning of each patient, plans-o were generated by experience physicists. After 20 fractions treatment, the corresponding plans-re were created with second CT scanning. And then, these two CT images were rigid and deformed registration respectively, and the dose was accumulated plan-o with plan-re. The dosimetry variation of these plans (plan-o: with 30 fractions, plan-rig: the accumulated dose with rigid registrationmore » and plan-def: the accumulated dose with deformed registration) were evaluated by paired T-test. Results: The V20 value of total lung were 32.68%, 30.3% and 29.71% for plan-o, plan-rig and plan-def respectively. The mean dose of total lung was 17.19 Gy, 16.67 Gy and 16.51 Gy for plan-o plan-rig and plan-def respectively. There were significant differences between plan-o and plan-rig or plan-def for both V20 and mean dose of total lung (with p= 0.003, p= 0.000 for V20 and p=0.008, p= 0.000 for mean dose respectively). There was no significant difference between plan-rig and plan-def (with p=0.118 for V20 and p=0.384 for mean dose). The max dose of spinal-cord was 41.95 Gy, 41.48 Gy and 41.4 Gy for plan-o, plan-rig and plan-def respectively. There were no significant differences for the max dose of spinal-cord between these plans. Conclusion: The target volume changes and anatomic position displacement of mid-thoracic esophageal carcinoma should not be neglected in clinics. These changes would cause overdose in normal tissue. Therefore, it is necessary to have another CT scanning and re-plan during the mid-thoracic esophageal carcinoma radiotherapy. And the dosimetry difference between rigid and deformed fusions was not found in this

[The use of polymer gel dosimetry to measure dose distribution around metallic implants].

PubMed

Nagahata, Tomomasa; Yamaguchi, Hajime; Monzen, Hajime; Nishimura, Yasumasa

2014-10-01

A semi-solid polymer dosimetry system using agar was developed to measure the dose distribution close to metallic implants. Dosimetry of heterogeneous fields where electron density markedly varies is often problematic. This prompted us to develop a polymer gel dosimetry technique using agar to measure the dose distribution near substance boundaries. Varying the concentration of an oxygen scavenger (tetra-hydroxymethyl phosphonium chloride) showed the absorbed dose and transverse relaxation rate of the magnetic resonance signal to be linear between 3 and 12 Gy. Although a change in the dosimeter due to oxidization was observed in room air after 24 hours, no such effects were observed in the first 4 hours. The dose distribution around the metal implants was measured using agar dosimetry. The metals tested were a lead rod, a titanium hip joint, and a metallic stent. A maximum 30% dose increase was observed near the lead rod, but only a 3% increase in the absorbed dose was noted near the surface of the titanium hip joint and metallic stent. Semi-solid polymer dosimetry using agar thus appears to be a useful method for dosimetry around metallic substances.

Application for internal dosimetry using biokinetic distribution of photons based on nuclear medicine images*

PubMed Central

Leal Neto, Viriato; Vieira, José Wilson; Lima, Fernando Roberto de Andrade

2014-01-01

Objective This article presents a way to obtain estimates of dose in patients submitted to radiotherapy with basis on the analysis of regions of interest on nuclear medicine images. Materials and Methods A software called DoRadIo (Dosimetria das Radiações Ionizantes [Ionizing Radiation Dosimetry]) was developed to receive information about source organs and target organs, generating graphical and numerical results. The nuclear medicine images utilized in the present study were obtained from catalogs provided by medical physicists. The simulations were performed with computational exposure models consisting of voxel phantoms coupled with the Monte Carlo EGSnrc code. The software was developed with the Microsoft Visual Studio 2010 Service Pack and the project template Windows Presentation Foundation for C# programming language. Results With the mentioned tools, the authors obtained the file for optimization of Monte Carlo simulations using the EGSnrc; organization and compaction of dosimetry results with all radioactive sources; selection of regions of interest; evaluation of grayscale intensity in regions of interest; the file of weighted sources; and, finally, all the charts and numerical results. Conclusion The user interface may be adapted for use in clinical nuclear medicine as a computer-aided tool to estimate the administered activity. PMID:25741101

Assessment of national dosimetry quality audits results for teletherapy machines from 1989 to 2015.

PubMed

Muhammad, Wazir; Ullah, Asad; Mahmood, Khalid; Matiullah

2016-01-01

The purpose of this study was to ensure accuracy in radiation dose delivery, external dosimetry quality audit has an equal importance with routine dosimetry performed at clinics. To do so, dosimetry quality audit was organized by the Secondary Standard Dosimetry Laboratory (SSDL) of Pakistan Institute of Nuclear Science and Technology (PINSTECH) at the national level to investigate and minimize uncertainties involved in the measurement of absorbed dose, and to improve the accuracy of dose measurement at different radiotherapy hospitals. A total of 181 dosimetry quality audits (i.e., 102 of Co-60 and 79 of linear accelerators) for teletherapy units installed at 22 different sites were performed from 1989 to 2015. The percent deviation between users’ calculated/stated dose and evaluated dose (in the result of on-site dosimetry visits) were calculated and the results were analyzed with respect to the limits of ± 2.5% (ICRU "optimal model") ± 3.0% (IAEA on-site dosimetry visits limit) and ± 5.0% (ICRU minimal or "lowest acceptable" model). The results showed that out of 181 total on-site dosimetry visits, 20.44%, 16.02%, and 4.42% were out of acceptable limits of ± 2.5% ± 3.0%, and ± 5.0%, respectively. The importance of a proper ongoing quality assurance program, recommendations of the followed protocols, and properly calibrated thermometers, pressure gauges, and humidity meters at radiotherapy hospitals are essential in maintaining consistency and uniformity of absorbed dose measurements for precision in dose delivery.

SU-F-T-565: Assessment of Dosimetric Accuracy for a 3D Gel-Based Dosimetry Service

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

Rosen, B; Lam, K; Moran, J

Purpose: To assess the 3D dosimetric accuracy when using a mail-in service for square and stereotactic fields in a clinical environment. Methods: The 3D dosimetry mail-in service (3DDaaS), offered by Modus QA (London, ON), was used to measure dose distributions from a 6 MV beam of a Varian Clinac. Plastic jars filled with radiosensitive ClearView™ gel were received, CT scanned (for registration and density information), irradiated, and then mailed back to the manufacturer for optical CT readout. Three square field irradiations (2×2, 4×4, and 10×10 cm{sup 2}) were performed with jars immobilized in a water tank, and a composite small-fieldmore » stereotactic delivery was performed using an in-air holder. Dosimetric properties of the gel were quantified within the 25–50 Gy dose range using 3D optical attenuation (OA) distributions provided by the manufacturer. OA was normalized to 100% at the position of isocenter, which received 40Gy. Percentage depth dose, profiles, and 3D gamma distributions (3%/1mm criteria) were calculated to quantify feasibility for relative dosimetry. Results: Mean CT-measured density in the central (3×3×3) cm{sup 3} gel region was 40 ± 3 HU, indicating good homogeneity and near-water-equivalence. Measured and calculated central axis doses agreed to within ±3% in the 25–50 Gy dose range. For the square field irradiations, dose profiles agreed to within 1mm. Gamma analysis of the composite irradiation yielded 99.8%, 91.4%, and 79.1% passing rates for regions receiving at least 10, 5, and 2 Gy, respectively, indicating feasibility for use in high-dose regions. Absolute response varied by up to 16% between jars, indicating limitations for absolute dosimetry under the mail-in conditions. Conclusion: 3DDaaS is a novel near-water-equivalent dosimetry system accurate to within 3% dose and 1mm 3D spatial resolution, and is straightforward to use in a clinical setting. Future investigations are warranted to improve dosimeter response in

Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

NASA Astrophysics Data System (ADS)

Galeano, D. C.; Cavalcante, F. R.; Carvalho, A. B.; Hunt, J.

2014-02-01

The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature.

Study of homogeneity and inhomogeneity phantom in CUDA EGS for small field dosimetry

NASA Astrophysics Data System (ADS)

Yani, Sitti; Rhani, Mohamad Fahdillah; Haryanto, Freddy; Arif, Idam

2017-02-01

CUDA EGS was CUDA implementation to simulate transport photon in a material based on Monte Carlo algorithm for X-ray imaging. The objective of this study was to investigate the effect of inhomogeneities in inhomogeneity phantom for small field dosimetry (1×1, 2×2, 3×3, 4×4 and 5×5 cm2). Two phantoms, homogeneity and inhomogeneity phantom were used. The interaction in homogeneity and inhomogeneity phantom was dominated by Compton interaction and multiple scattering. The CUDA EGS can represent the inhomogeneity effect in small field dosimetry by combining the grayscale curve between homogeneity and inhomogeneity phantom. The grayscale curve in inhomogeneity phantom is not asymmetric because of the existence of different material in phantom.

Hanford Internal Dosimetry Program Manual, PNL-MA-552

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

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2009-09-24

This manual is a guide to the services provided by the Hanford Internal Dosimetry Program (IDP), which is operated by the Pacific Northwest National Laboratory.( ) for the U.S. Department of Energy Richland Operations Office, Office of River Protection and their Hanford Site contractors. The manual describes the roles of and relationships between the IDP and the radiation protection programs of the Hanford Site contractors. Recommendations and guidance are also provided for consideration in implementing bioassay monitoring and internal dosimetry elements of radiation protection programs.

A new paradigm in personal dosimetry using LiF:Mg,Cu,P.

PubMed

Cassata, J R; Moscovitch, M; Rotunda, J E; Velbeck, K J

2002-01-01

The United States Navy has been monitoring personnel for occupational exposure to ionising radiation since 1947. Film was exclusively used until 1973 when thermoluminescence dosemeters were introduced and used to the present time. In 1994, a joint research project between the Naval Dosimetry Center, Georgetown University, and Saint Gobain Crystals and Detectors (formerly Bicron RMP formerly Harshaw TLD) began to develop a state of the art thermoluminescent dosimetry system. The study was conducted from a large-scale dosimetry processor point of view with emphasis on a systems approach. Significant improvements were achieved by replacing the LiF:Mg,Ti with LiF:Mg,Cu,P TL elements due to the significant sensitivity increase, linearity, and negligible hiding. Dosemeter filters were optimised for gamma and X ray energy discrimination using Monte Carlo modelling (MCNP) resulting in significant improvement in accuracy and precision. Further improvements were achieved through the use of neural-network based dose calculation algorithms. Both back propagation and functional link methods were implemented and the data compared with essentially the same results. Several operational aspects of the system are discussed, including (1) background subtraction using control dosemeters, (2) selection criteria for control dosemeters, (3) optimisation of the TLD readers, (4) calibration methodology, and (5) the optimisation of the heating profile.

Dosimetry analyses of the Ringhals 3 and 4 reactor pressure vessels

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

Kulesza, J.A.; Fero, A.H.; Rouden, J.

2011-07-01

A comprehensive series of neutron dosimetry measurements consisting of surveillance capsules, reactor pressure vessel cladding samples, and ex-vessel neutron dosimetry has been analyzed and compared to the results of three-dimensional, cycle-specific neutron transport calculations for the Ringhals Unit 3 and Unit 4 reactors in Sweden. The comparisons show excellent agreement between calculations and measurements. The measurements also demonstrate that it is possible to perform retrospective dosimetry measurements using the {sup 93}Nb (n,n') {sup 93m}Nb reaction on samples of 18-8 austenitic stainless steel with only trace amounts of elemental niobium. (authors)

Progress with the NCT international dosimetry exchange.

PubMed

Binns, P J; Riley, K J; Harling, O K; Auterinen, I; Marek, M; Kiger, W S

2004-11-01

The international collaboration that was organized to undertake a dosimetry exchange for purposes of combining clinical data from different facilities conducting neutron capture therapy has continued since its founding at the 9th ISNCT symposium in October 2000. The thrust towards accumulating physical dosimetry data for comparison between different participants has broadened to include facilities in Japan and the determination of spectral descriptions of different beams. Retrospective analysis of patient data from the Brookhaven Medical Research Reactor is also being considered for incorporation into this study to increase the pool of available data. Meanwhile the next essential phase of comparing measurements of visiting dosimetry groups with treatment plan calculations from the host institutes has commenced. Host centers from Petten, Finland and the Czech Republic in Europe and MIT in the USA have applied the regular calculations and clinical calibrations from their current clinical studies, to generate treatment plans in the large standard phantom used for measurements by visiting participants. These data have been exchanged between the participants and scaling factors to relate the separate dose components between the different institutes are being determined. Preliminary normalization of measured and calculated dosimetry for patients is nearing completion to enable the physical radiation doses that comprise a treatment prescription at a host institute to be directly related to the corresponding measured doses of a visiting group. This should serve as an impetus for the direct comparison of patient data although the clinical requirements for achieving this need to be clearly defined. This may necessitate more extensive comparisons of treatment planning calculations through the solution of test problems and clarification regarding the question of dose specification from treatment calculations in general.

A Monte Carlo model for the internal dosimetry of choroid plexuses in nuclear medicine procedures.

PubMed

Amato, Ernesto; Cicone, Francesco; Auditore, Lucrezia; Baldari, Sergio; Prior, John O; Gnesin, Silvano

2018-05-01

Choroid plexuses are vascular structures located in the brain ventricles, showing specific uptake of some diagnostic and therapeutic radiopharmaceuticals currently under clinical investigation, such as integrin-binding arginine-glycine-aspartic acid (RGD) peptides. No specific geometry for choroid plexuses has been implemented in commercially available software for internal dosimetry. The aims of the present study were to assess the dependence of absorbed dose to the choroid plexuses on the organ geometry implemented in Monte Carlo simulations, and to propose an analytical model for the internal dosimetry of these structures for 18 F, 64 Cu, 67 Cu, 68 Ga, 90 Y, 131 I and 177 Lu nuclides. A GAMOS Monte Carlo simulation based on direct organ segmentation was taken as the gold standard to validate a second simulation based on a simplified geometrical model of the choroid plexuses. Both simulations were compared with the OLINDA/EXM sphere model. The gold standard and the simplified geometrical model gave similar dosimetry results (dose difference < 3.5%), indicating that the latter can be considered as a satisfactory approximation of the real geometry. In contrast, the sphere model systematically overestimated the absorbed dose compared to both Monte Carlo models (range: 4-50% dose difference), depending on the isotope energy and organ mass. Therefore, the simplified geometric model was adopted to introduce an analytical approach for choroid plexuses dosimetry in the mass range 2-16 g. The proposed model enables the estimation of the choroid plexuses dose by a simple bi-parametric function, once the organ mass and the residence time of the radiopharmaceutical under investigation are provided. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Fundamentals of materials, techniques and instrumentation for OSL and FNTD dosimetry

NASA Astrophysics Data System (ADS)

Akselrod, M. S.

2013-02-01

The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al2O3:C as a material of choice for many dosimetric applications including fiberoptic OSL/RL sensors with diameters as small as 300 μm. A new RL/OSL fiberoptic system has a high potential for in vivo and in vitro dosimetry in both radiation therapy and diagnostic mammography. Different aspects of instrumentation, data processing algorithms, post-irradiation and real-time measurements are described. The next technological breakthrough was done with Fluorescent Nuclear Track detectors (FNTD) that has some important advantages in measuring fast neutron and high energy heavy charge particles that became the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology were engineered and successfully demonstrated for occupational and accident dosimetry, for medical dosimetry and radiobiological research.

Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy

NASA Astrophysics Data System (ADS)

Glaser, Adam Kenneth

Since its discovery in the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams. To advance this application, several novel techniques were implemented to realize the maximum potential of the signal, such as time-gating for maximizing the signal to noise ratio (SNR) and Cherenkov-excited fluorescence for generating isotropic light release in water. Proof of concept experiments were conducted in water tanks to demonstrate the feasibility of the proposed method for two-dimensional (2D) projection imaging, three-dimensional (3D) parallel beam tomography, large field of view 3D cone beam tomography, and video-rate dynamic imaging of treatment plans for a number of common radiotherapy applications. The proposed dosimetry method was found to have a number of unique advantages, including but not limited to its non-invasive nature, water-equivalence, speed, high-resolution, ability to provide full 3D data, and potential to yield data in-vivo. Based on

SU-E-T-580: On the Significance of Model Based Dosimetry for Breast and Head and Neck 192Ir HDR Brachytherapy

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

Peppa, V; Pappas, E; Pantelis, E

2015-06-15

Purpose: To assess the dosimetric and radiobiological differences between TG43-based and model-based dosimetry in the treatment planning of {sup 192}Ir HDR brachytherapy for breast and head and neck cancer. Methods: Two cohorts of 57 Accelerated Partial Breast Irradiation (APBI) and 22 head and neck (H&N) patients with oral cavity carcinoma were studied. Dosimetry for the treatment plans was performed using the TG43 algorithm of the Oncentra Brachy v4.4 treatment planning system (TPS). Corresponding Monte Carlo (MC) simulations were performed using MCNP6 with input files automatically prepared by the BrachyGuide software tool from DICOM RT plan data. TG43 and MC datamore » were compared in terms of % dose differences, Dose Volume Histograms (DVHs) and related indices of clinical interest for the Planning Target Volume (PTV) and the Organs-At-Risk (OARs). A radiobiological analysis was also performed using the Equivalent Uniform Dose (EUD), mean survival fraction (S) and Tumor Control Probability (TCP) for the PTV, and the Normal Tissue Control Probability (N TCP) and the generalized EUD (gEUD) for the OARs. Significance testing of the observed differences performed using the Wilcoxon paired sample test. Results: Differences between TG43 and MC DVH indices, associated with the increased corresponding local % dose differences observed, were statistically significant. This is mainly attributed to their consistency however, since TG43 agrees closely with MC for the majority of DVH and radiobiological parameters in both patient cohorts. Differences varied considerably among patients only for the ipsilateral lung and ribs in the APBI cohort, with a strong correlation to target location. Conclusion: While the consistency and magnitude of differences in the majority of clinically relevant DVH indices imply that no change is needed in the treatment planning practice, individualized dosimetry improves accuracy and addresses instances of inter-patient variability observed

Dosimetry and microdosimetry using COTS ICs: A comparative study

NASA Technical Reports Server (NTRS)

Scheick, L.; Swift, G.; Guertin, S.; Roth, D.; McNulty, P.; Nguyen, D.

2002-01-01

A new method using an array of MOS transistors formeasuring dose absorbed from ionizing radiation is compared to previous dosimetric methods., The accuracy and precision of dosimetry based on COTS SRAMs, DRAMs, and WPROMs are compared and contrasted. Applications of these devices in various space missions will be discussed. TID results are presented for this summary and microdosimetricresults will be added to the full paper. Finally, an analysis of the optimal condition for a digital dosimeter will be presented.

Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NIST, USA and the BIPM in medium-energy x-rays.

PubMed

Burns, D T; Kessler, C; O'Brien, M; Minniti, R

2012-01-01

A key comparison has been made between the air-kerma standards of the NIST, USA and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 10 3 , except at 250 kV where the difference is 1.5 times the standard uncertainty. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.

MIRD Pamphlet No. 21: A Generalized Schema for Radiopharmaceutical Dosimetry-Standardization of Nomenclature

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

Bolch, W E; Eckerman, Keith F; Sgouros, George

2009-03-01

The internal dosimetry schema of the Medical Internal Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine has provided a broad framework for assessment of the absorbed dose to whole organs, tissue subregions, voxelized tissue structures, and individual cellular compartments for use in both diagnostic and therapeutic nuclear medicine. The schema was originally published in 1968, revised in 1976, and republished in didactic form with comprehensive examples as the MIRD primer in 1988 and 1991. The International Commission on Radiological Protection (ICRP) is an organization that also supplies dosimetric models and technical data, for use in providing recommendations formore » limits on ionizing radiation exposure to workers and members of the general public. The ICRP has developed a dosimetry schema similar to that of the MIRD Committee but has used different terminology and symbols for fundamental quantities such as the absorbed fraction, specific absorbed fraction, and various dose coefficients. The MIRD Committee objectives for this pamphlet are 3-fold: to restate its schema for assessment of absorbed dose in a manner consistent with the needs of both the nuclear medicine and the radiation protection communities, with the goal of standardizing nomenclature; to formally adopt the dosimetry quantities equivalent dose and effective dose for use in comparative evaluations of potential risks of radiation-induced stochastic effects to patients after nuclear medicine procedures; and to discuss the need to identify dosimetry quantities based on absorbed dose that address deterministic effects relevant to targeted radionuclide therapy.« less

Poster - 19: Investigation of Electron Reference Dosimetry Based on Optimal Chamber Shift

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

Zhan, Lixin; Jiang, Runqing; Liu, Baochang

An addendum/revision to AAPM TG-51 electron reference dosimetry is highly expected to meet the clinical requirement with the increasing usage of new ion chambers not covered in TG-51. A recent study, Med. Phys. 41, 111701, proposed a new fitting equation for the beam quality conversion factor k’{sub Q} to a wide spectrum of chambers. In the study, an optimal Effective Point of Measurement (EPOM) from Monte Carlo calculations was recommended and the fitting parameters to k’{sub Q} was based on it. We investigated the absolute dose obtained based on the optimal EPOM method and the original TG-51 method with k’{submore » R50} determined differently. The results showed that using the Markus curve is a better choice than the well-guarded chamber fitting for an IBA PPC-05 parallel plate chamber if we need to strictly follow the AAPM TG-51 protocol. We also examined the usage of the new fitting equation with measurement performed at the physical EPOM, instead of the optimal EPOM. The former is more readily determined and more practical in clinics. Our study indicated that the k’{sub Q} fitting based on the optimal EPOM can be used to measurement at the physical EPOM with no significant clinical impact. The inclusion of Farmer chamber gradient correction P{sub gr} in k’{sub Q}, as in the mentioned study, asks for the precise positioning of chamber center at dref. It is not recommended in clinics to avoid over-correction for low electron energies, especially for an institute having matching Linacs implemented.« less

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

NASA Astrophysics Data System (ADS)

Watson, Peter G. F.; Popovic, Marija; Seuntjens, Jan

2018-01-01

Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, CQ , to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work CQ was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that CQ was sensitive to the chamber plate separation tolerance, with differences of up to 15%. CQ was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, CQ was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

Software tool for portal dosimetry research.

PubMed

Vial, P; Hunt, P; Greer, P B; Oliver, L; Baldock, C

2008-09-01

This paper describes a software tool developed for research into the use of an electronic portal imaging device (EPID) to verify dose for intensity modulated radiation therapy (IMRT) beams. A portal dose image prediction (PDIP) model that predicts the EPID response to IMRT beams has been implemented into a commercially available treatment planning system (TPS). The software tool described in this work was developed to modify the TPS PDIP model by incorporating correction factors into the predicted EPID image to account for the difference in EPID response to open beam radiation and multileaf collimator (MLC) transmitted radiation. The processes performed by the software tool include; i) read the MLC file and the PDIP from the TPS, ii) calculate the fraction of beam-on time that each point in the IMRT beam is shielded by MLC leaves, iii) interpolate correction factors from look-up tables, iv) create a corrected PDIP image from the product of the original PDIP and the correction factors and write the corrected image to file, v) display, analyse, and export various image datasets. The software tool was developed using the Microsoft Visual Studio.NET framework with the C# compiler. The operation of the software tool was validated. This software provided useful tools for EPID dosimetry research, and it is being utilised and further developed in ongoing EPID dosimetry and IMRT dosimetry projects.

Reconstructive dosimetry for cutaneous radiation syndrome

PubMed Central

Lima, C.M.A.; Lima, A.R.; Degenhardt, Ä.L.; Valverde, N.J.; Da Silva, F.C.A.

2015-01-01

According to the International Atomic Energy Agency (IAEA), a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS) in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry. PMID:26445332

Monte Carlo investigation of backscatter factors for skin dose determination in interventional neuroradiology procedures

NASA Astrophysics Data System (ADS)

Omar, Artur; Benmakhlouf, Hamza; Marteinsdottir, Maria; Bujila, Robert; Nowik, Patrik; Andreo, Pedro

2014-03-01

Complex interventional and diagnostic x-ray angiographic (XA) procedures may yield patient skin doses exceeding the threshold for radiation induced skin injuries. Skin dose is conventionally determined by converting the incident air kerma free-in-air into entrance surface air kerma, a process that requires the use of backscatter factors. Subsequently, the entrance surface air kerma is converted into skin kerma using mass energy-absorption coefficient ratios tissue-to-air, which for the photon energies used in XA is identical to the skin dose. The purpose of this work was to investigate how the cranial bone affects backscatter factors for the dosimetry of interventional neuroradiology procedures. The PENELOPE Monte Carlo system was used to calculate backscatter factors at the entrance surface of a spherical and a cubic water phantom that includes a cranial bone layer. The simulations were performed for different clinical x-ray spectra, field sizes, and thicknesses of the bone layer. The results show a reduction of up to 15% when a cranial bone layer is included in the simulations, compared with conventional backscatter factors calculated for a homogeneous water phantom. The reduction increases for thicker bone layers, softer incident beam qualities, and larger field sizes, indicating that, due to the increased photoelectric crosssection of cranial bone compared to water, the bone layer acts primarily as an absorber of low-energy photons. For neurointerventional radiology procedures, backscatter factors calculated at the entrance surface of a water phantom containing a cranial bone layer increase the accuracy of the skin dose determination.

Uncertainty propagation for SPECT/CT-based renal dosimetry in 177Lu peptide receptor radionuclide therapy

NASA Astrophysics Data System (ADS)

Gustafsson, Johan; Brolin, Gustav; Cox, Maurice; Ljungberg, Michael; Johansson, Lena; Sjögreen Gleisner, Katarina

2015-11-01

A computer model of a patient-specific clinical 177Lu-DOTATATE therapy dosimetry system is constructed and used for investigating the variability of renal absorbed dose and biologically effective dose (BED) estimates. As patient models, three anthropomorphic computer phantoms coupled to a pharmacokinetic model of 177Lu-DOTATATE are used. Aspects included in the dosimetry-process model are the gamma-camera calibration via measurement of the system sensitivity, selection of imaging time points, generation of mass-density maps from CT, SPECT imaging, volume-of-interest delineation, calculation of absorbed-dose rate via a combination of local energy deposition for electrons and Monte Carlo simulations of photons, curve fitting and integration to absorbed dose and BED. By introducing variabilities in these steps the combined uncertainty in the output quantity is determined. The importance of different sources of uncertainty is assessed by observing the decrease in standard deviation when removing a particular source. The obtained absorbed dose and BED standard deviations are approximately 6% and slightly higher if considering the root mean square error. The most important sources of variability are the compensation for partial volume effects via a recovery coefficient and the gamma-camera calibration via the system sensitivity.

Cholesteric liquid crystals as sensor materials for bioequivalent UV-dosimetry

NASA Astrophysics Data System (ADS)

Lisetski, Longin N.; Vashchenko, O. V.; Panikarskaya, V. D.; Sidletskiy, O. T.; Terenetskaya, Irina P.

2003-12-01

Selective reflection spectra have been studied for cholesteric matrices doped with certain steroids of vitamin D group, and substantial effect of the dopants upon the helical pitch was noted. Under UV irradiation, shifts of selective reflection peaks were observed. It is argued that the effect studied can be used for monitoring of vitamin D formation reactions induced by UV irradiation, thus being a base of bioequivalent UV dosimetry.

Deformable registration of x-ray to MRI for post-implant dosimetry in prostate brachytherapy

NASA Astrophysics Data System (ADS)

Park, Seyoun; Song, Danny Y.; Lee, Junghoon

2016-03-01

Post-implant dosimetric assessment in prostate brachytherapy is typically performed using CT as the standard imaging modality. However, poor soft tissue contrast in CT causes significant variability in target contouring, resulting in incorrect dose calculations for organs of interest. CT-MR fusion-based approach has been advocated taking advantage of the complementary capabilities of CT (seed identification) and MRI (soft tissue visibility), and has proved to provide more accurate dosimetry calculations. However, seed segmentation in CT requires manual review, and the accuracy is limited by the reconstructed voxel resolution. In addition, CT deposits considerable amount of radiation to the patient. In this paper, we propose an X-ray and MRI based post-implant dosimetry approach. Implanted seeds are localized using three X-ray images by solving a combinatorial optimization problem, and the identified seeds are registered to MR images by an intensity-based points-to-volume registration. We pre-process the MR images using geometric and Gaussian filtering. To accommodate potential soft tissue deformation, our registration is performed in two steps, an initial affine transformation and local deformable registration. An evolutionary optimizer in conjunction with a points-to-volume similarity metric is used for the affine registration. Local prostate deformation and seed migration are then adjusted by the deformable registration step with external and internal force constraints. We tested our algorithm on six patient data sets, achieving registration error of (1.2+/-0.8) mm in < 30 sec. Our proposed approach has the potential to be a fast and cost-effective solution for post-implant dosimetry with equivalent accuracy as the CT-MR fusion-based approach.

ESR/Alanine gamma-dosimetry in the 10-30 Gy range.

PubMed

Fainstein, C; Winkler, E; Saravi, M

2000-05-01

We report Alanine Dosimeter preparation, procedures for using the ESR/Dosimetry method, and the resulting calibration curve for gamma-irradiation in the range from 10-30 Gy. We use calibration curve to measure the irradiation dose in gamma-irradiation of human blood, as required in Blood Transfusion Therapy. The ESR/Alanine results are compared against those obtained using the thermoluminescent dosimetry (TLD) method.

Breast dosimetry in clinical mammography

NASA Astrophysics Data System (ADS)

Benevides, Luis Alberto Do Rego

The objective of this study was show that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. In the study, AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The protocol proposes the use of a fiber-optic coupled (FOCD) or Metal Oxide Semiconductor Field Effect Transistor (MOSFET) dosimeter to measure the entrance skin exposure at the time of the mammogram without interfering with diagnostic information of the mammogram. The study showed that FOCD had sensitivity with less than 7% energy dependence, linear in all tube current-time product stations, and was reproducible within 2%. FOCD was superior to MOSFET dosimeter in sensitivity, reusability, and reproducibility. The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. In addition, the study population anthropometric

Reducing the number of CTs performed to monitor personalized dosimetry during peptide receptor radionuclide therapy (PRRT).

PubMed

Chicheportiche, Alexandre; Artoul, Faozi; Schwartz, Arnon; Grozinsky-Glasberg, Simona; Meirovitz, Amichay; Gross, David J; Godefroy, Jeremy

2018-06-19

Peptide receptor radionuclide therapy (PRRT) with [ 177 Lu]-DOTA-TATE is an effective treatment of neuroendocrine tumors (NETs). After each cycle of treatment, patient dosimetry evaluates the radiation dose to the risk organs, kidneys, and bone marrow, the most radiosensitive tissues. Absorbed doses are calculated from the radioactivity in the blood and from single photon emission computed tomography (SPECT) images corrected by computed tomography (CT) acquired after each course of treatment. The aim of this work is to assess whether the dosimetry along all treatment cycles can be calculated using a single CT. We hypothesize that the absorbed doses to the risk organs calculated with a single CT will be accurate enough to correctly manage the patients, i.e., whether or not to continue PRRT. Twenty-four patients diagnosed with metastatic NETs undergoing PRRT with [ 177 Lu]-DOTA-TATE were retrospectively included in this study. We compared radiation doses to the kidneys and bone marrow using two protocols. In the "classical" one, dosimetry is calculated based on a SPECT and a CT after each treatment cycle. In the new protocol, dosimetry is calculated based on a SPECT study after each cycle but with the first acquired CT for all cycles. The decision whether or not to stop PRRT because of unsafe absorbed dose to the risk organs would have been the same had the classical or the new protocol been used. The agreement between the cumulative doses to the kidneys and bone marrow obtained from the two protocols was excellent with Pearson's correlation coefficients r = 0.95 and r = 0.99 (P < 0.0001) and mean relative differences of 5.30 ± 6.20% and 0.48 ± 4.88%, respectively. Dosimetry calculations for a given patient can be done using a single CT registered to serial SPECTs. This new protocol reduces the need for a hybrid camera in the follow-up of patients receiving [ 177 Lu]-DOTA-TATE.

Dosimetry quality audit of high energy photon beams in greek radiotherapy centers.

PubMed

Hourdakis, Constantine J; Boziari, A

2008-04-01

Dosimetry quality audits and intercomparisons in radiotherapy centers is a useful tool in order to enhance the confidence for an accurate therapy and to explore and dissolve discrepancies in dose delivery. This is the first national comprehensive study that has been carried out in Greece. During 2002--2006 the Greek Atomic Energy Commission performed a dosimetry quality audit of high energy external photon beams in all (23) Greek radiotherapy centers, where 31 linacs and 13 Co-60 teletherapy units were assessed in terms of their mechanical performance characteristics and relative and absolute dosimetry. The quality audit in dosimetry of external photon beams took place by means of on-site visits, where certain parameters of the photon beams were measured, calculated and assessed according to a specific protocol and the IAEA TRS 398 dosimetry code of practice. In each radiotherapy unit (Linac or Co-60), certain functional parameters were measured and the results were compared to tolerance values and limits. Doses in water under reference and non reference conditions were measured and compared to the stated values. Also, the treatment planning systems (TPS) were evaluated with respect to irradiation time calculations. The results of the mechanical tests, dosimetry measurements and TPS evaluation have been presented in this work and discussed in detail. This study showed that Co-60 units had worse performance mechanical characteristics than linacs. 28% of all irradiation units (23% of linacs and 42% of Co-60 units) exceeded the acceptance limit at least in one mechanical parameter. Dosimetry accuracy was much worse in Co60 units than in linacs. 61% of the Co60 units exhibited deviations outside +/-3% and 31% outside +/-5%. The relevant percentages for the linacs were 24% and 7% respectively. The results were grouped for each hospital and the sources of errors (functional and human) have been investigated and discussed in details. This quality audit proved to be a

Combined model-based and patient-specific dosimetry for 18F-DCFPyL, a PSMA-targeted PET agent.

PubMed

Plyku, Donika; Mena, Esther; Rowe, Steven P; Lodge, Martin A; Szabo, Zsolt; Cho, Steve Y; Pomper, Martin G; Sgouros, George; Hobbs, Robert F

2018-06-01

Prostate-specific membrane antigen (PSMA), a type-II integral membrane protein highly expressed in prostate cancer, has been extensively used as a target for imaging and therapy. Among the available PET radiotracers, the low molecular weight agents that bind to PSMA are proving particularly effective. We present the dosimetry results for 18 F-DCFPyL in nine patients with metastatic prostate cancer. Nine patients were imaged using sequential PET/CT scans at approximately 1, 12, 35 and 70 min, and a final PET/CT scan at approximately 120 min after intravenous administration of 321 ± 8 MBq (8.7 ± 0.2 mCi) of 18 F-DCFPyL. Time-integrated-activity coefficients were calculated and used as input in OLINDA/EXM software to obtain dose estimates for the majority of the major organs. The absorbed doses (AD) to the eye lens and lacrimal glands were calculated using Monte-Carlo models based on idealized anatomy combined with patient-specific volumes and activity from the PET/CT scans. Monte-Carlo based models were also developed for calculation of the dose to two major salivary glands (parotid and submandibular) using CT-based patient-specific gland volumes. The highest calculated mean AD per unit administered activity of 18 F was found in the lacrimal glands, followed by the submandibular glands, kidneys, urinary bladder wall, and parotid glands. The S-values for the lacrimal glands to the eye lens (0.42 mGy/MBq h), the tear film to the eye lens (1.78 mGy/MBq h) and the lacrimal gland self-dose (574.10 mGy/MBq h) were calculated. Average S-values for the salivary glands were 3.58 mGy/MBq h for the parotid self-dose and 6.78 mGy/MBq h for the submandibular self-dose. The resultant mean effective dose of 18 F-DCFPyL was 0.017 ± 0.002 mSv/MBq. 18 F-DCFPyL dosimetry in nine patients was obtained using novel models for the lacrimal and salivary glands, two organs with potentially dose-limiting uptake for therapy and diagnosis which lacked pre

Gamma response characterizations of optically stimulated luminescence (OSL) affects personal dosimetry

NASA Astrophysics Data System (ADS)

Monthonwattana, S.; Esor, J.; Rungseesumran, T.; Intang, A.

2017-06-01

Optically Stimulated Luminescence (OSL) is the current technique of personal dosimetry changed by Nuclear Technology Service Center instead of Thermoluminescence dosimetry (TLD) because OSL has more advantages, such as repeat reading and elimination of heating process. In this study, OSL was used to test the gamma response characterizations. Detailed OSL investigation on personal dosimetry was carried out in the dose range of 0.2 - 3.0 mSv. The batch homogeneity was 7.66%. R2 value of the linear regression was 0.9997. The difference ratio of angular dependence at ± 60° was 8.7%. Fading of the reading was about 3%.

The Mayak Worker Dosimetry System (Mwds-2013): An Introduction to The Documentation

DOE PAGES

Napier, B. A.

2017-03-17

The reconstruction of radiation doses to Mayak Production Association workers in central Russia supports radiation epidemiological studies for the U.S.-Russian Joint Coordinating Committee on Radiation Effects Research. The most recent version of the dosimetry was performed with the Mayak Worker Dosimetry System-2013. Here, this introduction outlines the logic and general content of the series of articles presented in this issue of Radiation Protection Dosimetry. The articles summarize the models, describe the basis for most of the key decisions made in developing the models and present an overview of the results.

The Mayak Worker Dosimetry System (Mwds-2013): An Introduction to The Documentation

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

Napier, B. A.

The reconstruction of radiation doses to Mayak Production Association workers in central Russia supports radiation epidemiological studies for the U.S.-Russian Joint Coordinating Committee on Radiation Effects Research. The most recent version of the dosimetry was performed with the Mayak Worker Dosimetry System-2013. Here, this introduction outlines the logic and general content of the series of articles presented in this issue of Radiation Protection Dosimetry. The articles summarize the models, describe the basis for most of the key decisions made in developing the models and present an overview of the results.

Fiber-coupled Luminescence Dosimetry in Therapeutic and Diagnostic Radiology

NASA Astrophysics Data System (ADS)

Andersen, Claus E.

2011-05-01

Fiber-coupled luminescence dosimetry is an emerging technology with several potentially attractive features of relevance for uses in therapeutic and diagnostic radiology: direct water equivalence (i.e. no significant perturbation of the radiation field in a water phantom or a patient), sub-mm detector size, high dynamic range (below a mGy to several Gy), microsecond time resolution, and absence of electrical wires or other electronics in the dosimeter probe head. Fiber-coupled luminescence dosimetry systems typically consist of one or more small samples of phosphor, e.g. a mg of plastic scintillator, attached to 10-20 m long optical fiber cables of plastic. During irradiation, each dosimeter probe spontaneously emits radioluminescence (RL) in proportion to the dose rate. The luminescence intensity can be detected with photomultiplier tubes, CCD cameras or other highly sensitive photodetectors. Some crystalline phosphors, such as carbon-doped aluminium oxide (Al2O3:C) have the ability to store charge produced in the crystal during irradiation. The stored charge may later be released by fiber-guided laser light under emission of so-called optically stimulated luminescence (OSL). The OSL signal therefore reflects the passively integrated dose. In contrast to thermoluminescence dosimetry, fiber-coupled OSL dosimetry may be performed in vivo while the dosimeter is still in the patient. Within the last few years, several improvements and new applications of these techniques have been published, and the objective of this review is to provide an introduction to this field and to outline some of these new results. Emphasis will be given to applications in medical dosimetry such as in vivo real-time dose verification in brachytherapy and methods aimed for improved quality assurance of linear accelerators.

A review of recent advances in optical fibre sensors for in vivo dosimetry during radiotherapy

PubMed Central

O'Keeffe, S; McCarthy, D; Woulfe, P; Grattan, M W D; Hounsell, A R; Sporea, D; Mihai, L; Vata, I; Leen, G

2015-01-01

This article presents an overview of the recent developments and requirements in radiotherapy dosimetry, with particular emphasis on the development of optical fibre dosemeters for radiotherapy applications, focusing particularly on in vivo applications. Optical fibres offer considerable advantages over conventional techniques for radiotherapy dosimetry, owing to their small size, immunity to electromagnetic interferences, and suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based dosemeters, together with being lightweight and flexible, mean that they are minimally invasive and thus particularly suited to in vivo dosimetry. This means that the sensor can be placed directly inside a patient, for example, for brachytherapy treatments, the optical fibres could be placed in the tumour itself or into nearby critical tissues requiring monitoring, via the same applicators or needles used for the treatment delivery thereby providing real-time dosimetric information. The article outlines the principal sensor design systems along with some of the main strengths and weaknesses associated with the development of these techniques. The successful demonstration of these sensors in a range of different clinical environments is also presented. PMID:25761212

Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NIST, USA and the BIPM in medium-energy x-rays

PubMed Central

Burns, D T; Kessler, C; O’Brien, M; Minniti, R

2017-01-01

A key comparison has been made between the air-kerma standards of the NIST, USA and the BIPM in the medium-energy x–ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 103, except at 250 kV where the difference is 1.5 times the standard uncertainty. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. PMID:28966399

Technical basis for internal dosimetry at Hanford

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

Sula, M.J.; Carbaugh, E.H.; Bihl, D.E.

1991-07-01

The Hanford Internal Dosimetry Program, administered by Pacific Northwest Laboratory for the US Department of Energy, provides routine bioassay monitoring for employees who are potentially exposed to radionuclides in the workplace. This report presents the technical basis for routine bioassay monitoring and the assessment of internal dose at Hanford. The radionuclides of concern include tritium, corrosion products ({sup 58}Co, {sup 60}Co, {sup 54}Mn, and {sup 59}Fe), strontium, cesium, iodine, europium, uranium, plutonium, and americium,. Sections on each of these radionuclides discuss the sources and characteristics; dosimetry; bioassay measurements and monitoring; dose measurement, assessment, and mitigation and bioassay follow-up treatment. 78more » refs., 35 figs., 115 tabs.« less

Technical basis for internal dosimetry at Hanford

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

Sula, M.J.; Carbaugh, E.H.; Bihl, D.E.

1989-04-01

The Hanford Internal Dosimetry Program, administered by Pacific Northwest Laboratory for the US Department of Energy, provides routine bioassay monitoring for employees who are potentially exposed to radionuclides in the workplace. This report presents the technical basis for routine bioassay monitoring and the assessment of internal dose at Hanford. The radionuclides of concern include tritium, corrosion products (/sup 58/Co, /sup 60/Co, /sup 54/Mn, and /sup 59/Fe), strontium, cesium, iodine, europium, uranium, plutonium, and americium. Sections on each of these radionuclides discuss the sources and characteristics; dosimetry; bioassay measurements and monitoring; dose measurement, assessment, and mitigation; and bioassay follow-up treatment. 64more » refs., 42 figs., 118 tabs.« less

Trigeminal neuralgia treatment dosimetry of the Cyberknife

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

Ho, Anthony; Lo, Anthony T., E-mail: tonyho22003@yahoo.com; Dieterich, Sonja

2012-04-01

There are 2 Cyberknife units at Stanford University. The robot of 1 Cyberknife is positioned on the patient's right, whereas the second is on the patient's left. The present study examines whether there is any difference in dosimetry when we are treating patients with trigeminal neuralgia when the target is on the right side or the left side of the patient. In addition, we also study whether Monte Carlo dose calculation has any effect on the dosimetry. We concluded that the clinical and dosimetric outcomes of CyberKnife treatment for trigeminal neuralgia are independent of the robot position. Monte Carlo calculationmore » algorithm may be useful in deriving the dose necessary for trigeminal neuralgia treatments.« less

INTERSPECIES DOSIMETRY MODELS FOR PULMONARY PHARMACOLOGY

EPA Science Inventory

Interspecies Dosimetry Models for Pulmonary Pharmacology

Ted B. Martonen, Jeffry D. Schroeter, and John S. Fleming

Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangl...

The polyGeVero® software for fast and easy computation of 3D radiotherapy dosimetry data

NASA Astrophysics Data System (ADS)

Kozicki, Marek; Maras, Piotr

2015-01-01

The polyGeVero® software package was elaborated for calculations of 3D dosimetry data such as the polymer gel dosimetry. It comprises four workspaces designed for: i) calculating calibrations, ii) storing calibrations in a database, iii) calculating dose distribution 3D cubes, iv) comparing two datasets e.g. a measured one with a 3D dosimetry with a calculated one with the aid of a treatment planning system. To accomplish calculations the software was equipped with a number of tools such as the brachytherapy isotopes database, brachytherapy dose versus distance calculation based on the line approximation approach, automatic spatial alignment of two 3D dose cubes for comparison purposes, 3D gamma index, 3D gamma angle, 3D dose difference, Pearson's coefficient, histograms calculations, isodoses superimposition for two datasets, and profiles calculations in any desired direction. This communication is to briefly present the main functions of the software and report on the speed of calculations performed by polyGeVero®.

WE-F-201-03: Evaluate Clinical Cases Using Commercially Available Systems and Compare to TG-43 Dosimetry

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

Beaulieu, L.

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently-published AAPM TG-186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM-ESTRO-ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well-defined test case plans, available as references in the software commissioning process to be performed by clinical end-users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of themore » clinical impact from recent literature reporting comparisons of TG-43 and heterogeneity-based dosimetry. Learning Objectives: Identify key clinical applications needing advanced dose calculation in brachytherapy. Review TG-186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks. Evaluate clinical cases using commercially available systems and compare to TG-43 dosimetry.« less

A multicentre 'end to end' dosimetry audit for cervix HDR brachytherapy treatment.

PubMed

Palmer, Antony L; Diez, Patricia; Gandon, Laura; Wynn-Jones, Andrea; Bownes, Peter; Lee, Chris; Aird, Edwin; Bidmead, Margaret; Lowe, Gerry; Bradley, David; Nisbet, Andrew

2015-02-01

To undertake the first multicentre fully 'end to end' dosimetry audit for HDR cervix brachytherapy, comparing planned and delivered dose distributions around clinical treatment applicators, with review of local procedures. A film-dosimetry audit was performed at 46 centres, including imaging, applicator reconstruction, treatment planning and delivery. Film dose maps were calculated using triple-channel dosimetry and compared to RTDose data from treatment planning systems. Deviations between plan and measurement were quantified at prescription Point A and using gamma analysis. Local procedures were also discussed. The mean difference between planned and measured dose at Point A was -0.6% for plastic applicators and -3.0% for metal applicators, at standard uncertainty 3.0% (k=1). Isodose distributions agreed within 1mm over a dose range 2-16Gy. Mean gamma passing rates exceeded 97% for plastic and metal applicators at 3% (local) 2mm criteria. Two errors were found: one dose normalisation error and one applicator library misaligned with the imaged applicator. Suggestions for quality improvement were also made. The concept of 'end to end' dosimetry audit for HDR brachytherapy has been successfully implemented in a multicentre environment, providing evidence that a high level of accuracy in brachytherapy dosimetry can be achieved. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Using exposure prediction tools to link exposure and dosimetry for risk based decisions: a case study with phthalates

EPA Science Inventory

The Population Life-course Exposure to Health Effects Modeling (PLETHEM) platform being developed provides a tool that links results from emerging toxicity testing tools to exposure estimates for humans as defined by the USEPA. A reverse dosimetry case study using phthalates was ...

TU-C-BRE-11: 3D EPID-Based in Vivo Dosimetry: A Major Step Forward Towards Optimal Quality and Safety in Radiation Oncology Practice

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

Mijnheer, B; Mans, A; Olaciregui-Ruiz, I

Purpose: To develop a 3D in vivo dosimetry method that is able to substitute pre-treatment verification in an efficient way, and to terminate treatment delivery if the online measured 3D dose distribution deviates too much from the predicted dose distribution. Methods: A back-projection algorithm has been further developed and implemented to enable automatic 3D in vivo dose verification of IMRT/VMAT treatments using a-Si EPIDs. New software tools were clinically introduced to allow automated image acquisition, to periodically inspect the record-and-verify database, and to automatically run the EPID dosimetry software. The comparison of the EPID-reconstructed and planned dose distribution is donemore » offline to raise automatically alerts and to schedule actions when deviations are detected. Furthermore, a software package for online dose reconstruction was also developed. The RMS of the difference between the cumulative planned and reconstructed 3D dose distributions was used for triggering a halt of a linac. Results: The implementation of fully automated 3D EPID-based in vivo dosimetry was able to replace pre-treatment verification for more than 90% of the patient treatments. The process has been fully automated and integrated in our clinical workflow where over 3,500 IMRT/VMAT treatments are verified each year. By optimizing the dose reconstruction algorithm and the I/O performance, the delivered 3D dose distribution is verified in less than 200 ms per portal image, which includes the comparison between the reconstructed and planned dose distribution. In this way it was possible to generate a trigger that can stop the irradiation at less than 20 cGy after introducing large delivery errors. Conclusion: The automatic offline solution facilitated the large scale clinical implementation of 3D EPID-based in vivo dose verification of IMRT/VMAT treatments; the online approach has been successfully tested for various severe delivery errors.« less

SU-E-T-92: Achieving Desirable Lung Doses in Total Body Irradiation Based On in Vivo Dosimetry and Custom Tissue Compensation

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

Cui, G; Shiu, A; Zhou, S

Purpose: To achieve desirable lung doses in total body irradiation (TBI) based on in vivo dosimetry and custom tissue compensation. Methods: The 15 MV photon beam of a Varian TrueBeam STx linac was used for TBI. Patients were positioned in the lateral decubitus position for AP/PA treatment delivery. Dose was calculated using the midpoint of the separation distance across the patient’s umbilicus. Patients received 200 cGy twice daily for 3 days. The dose rate at the patient’s midplane was approximately 10 cGy/min. Cerrobend blocks with a 5-HVL thickness were used for the primary lung shielding. A custom styrofoam holder formore » rice-flour filled bags was created based on the lung block cutouts. This was used to provide further lung shielding based on in vivo dose measurements. Lucite plates and rice-flour bags were placed in the head, neck, chest, and lower extremity regions during the treatment to compensate for the beam off-axis output variations. Two patients were included in the study. Patients 1 and 2 received a craniospinal treatment (1080 cGy) and a mediastinum treatment (2520 cGy), respectively, before the TBI. During the TBI nanoDot dosimeters were placed on the patient skin in the forehead, neck, umbilicus, and lung regions for dose monitoring. The doses were readout immediately after the treatment. Based on the readings, fine tuning of the thickness of the rice-flour filled bags was exploited to achieve the desirable lung doses. Results: For both patients the mean lung doses, which took into consideration all treatments, were controlled within 900 +/−10% cGy, as desired. Doses to the forehead, neck, and umbilicus were achieved within +/−10% of the prescribed dose (1200 cGy). Conclusion: A reliable and robust method was developed to achieve desirable lung doses and uniform body dose in TBI based on in vivo dosimetry and custom tissue compensator.« less

New developments in EPID-based 3D dosimetry in The Netherlands Cancer Institute

NASA Astrophysics Data System (ADS)

Mijnheer, B.; Rozendaal, R.; Olaciregui-Ruiz, I.; González, P.; van Oers, R.; Mans, A.

2017-05-01

EPID-based offline 3D in vivo dosimetry is performed routinely in The Netherlands Cancer Institute for almost all RT treatments. The 3D dose distribution is reconstructed using the EPID primary dose in combination with a back-projection algorithm and compared with the planned dose distribution. Recently the method was adapted for real-time dose verification, performing 3D dose verification in less than 300 ms, which is faster than the current portal frame acquisition rate. In this way a possibility is created for halting the linac in case of large delivery errors. Furthermore, a new method for pre-treatment QA was developed in which the EPID primary dose behind a phantom or patient is predicted using the CT data of that phantom or patient in combination with in-air EPID measurements. This virtual EPID primary transit dose is then used to reconstruct the 3D dose distribution within the phantom or patient geometry using the same dose engine as applied offline. In order to assess the relevance of our clinically applied alert criteria, we investigated the sensitivity of our EPID-based 3D dose verification system to detect delivery errors in VMAT treatments. This was done through simulation by modifying patient treatment plans, as well as experimentally by performing EPID measurements during the irradiation of an Alderson phantom, both after deliberately introducing errors during VMAT delivery. In this presentation these new developments will be elucidated.

SU-G-TeP2-03: Comparison of Standard Dosimetry Protocol in Japan and AAPM TG-51 Addendum in Order to Establish Optimal Dosimetry for FFF Beam

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

Matsunaga, T; Adachi, Y; Hayashi, N

Purpose: Japan Standard Dosimetry of Absorbed dose to water in external beam radiotherapy (JSDP12) is widely used to measure radiation dose in radiotherapy. However, JSDP12 does not take flattening-filter-free (FFF) beam into consideration. In addition, JSDP12 applied TPR20,10 for dose quality index for photon beam. The purpose of this study is to compare JSDP12 with AAPM TG-51 addendum in order to establish optimal dosimetry procedure for FFF beam. Method: We evaluated the ion-recombination factor (ks) and the correction factor of radial beam profile (Prp) in FFF beam dosimetry. The ks was introduced by 2 voltages method and verified by Jaffe’smore » plot. The Prp was given by both film measurement and calculation of treatment planning system, and compared them. Next, we compared the dose quality indexes (kQ) between TPR20,10 method and PDD(10)x method. Finally we considered optimal dosimetry protocol for FFF photon beam using JSDP12 with referring TG-51 addendum protocols. The FFF photon beams of 6 MV (6X-FFF) and 10 MV (10X-FFF) from TrueBeam were investigated in this study. Results: The ks for 6X-FFF and 10X-FFF beams were 1.005 and 1.010, respectively. The Prp of 0.6 cc ionization chamber for 6X-FFF and 10X-FFF beams (Film, TPS) were (1.004, 1.008) and (1.005, 1.008), respectively. The kQ for 6X-FFF and 10X-FFF beams (JSDP12, TG-51 addendum) were (0.9950, 0.9947) and (0.9851, 0.9845), respectively. The most effective factor for uncertainty in FFF photon beam measurement was Prp for JSDP12 formalism. Total dosimetric differences between JSDP12 and TG-51 addendum for 6X-FFF and 10X-FFF were -0.47% and -0.73%, respectively. Conclusion: The total dosimetric difference between JSDP12 and TG-51 addendum was within 1%. The introduction of kQ given by JSDP is feasible for FFF photon beam dosimetry. However, we think Prp should be considered for optimal dosimetry procedure even if JSDP12 is used for FFF photon beam dosimetry.« less

A practical three-dimensional dosimetry system for radiation therapy

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

Guo Pengyi; Adamovics, John; Oldham, Mark

2006-10-15

There is a pressing need for a practical three-dimensional (3D) dosimetry system, convenient for clinical use, and with the accuracy and resolution to enable comprehensive verification of the complex dose distributions typical of modern radiation therapy. Here we introduce a dosimetry system that can achieve this challenge, consisting of a radiochromic dosimeter (PRESAGE trade mark sign ) and a commercial optical computed tomography (CT) scanning system (OCTOPUS trade mark sign ). PRESAGE trade mark sign is a transparent material with compelling properties for dosimetry, including insensitivity of the dose response to atmospheric exposure, a solid texture negating the need formore » an external container (reducing edge effects), and amenability to accurate optical CT scanning due to radiochromic optical contrast as opposed to light-scattering contrast. An evaluation of the performance and viability of the PRESAGE trade mark sign /OCTOPUS, combination for routine clinical 3D dosimetry is presented. The performance of the two components (scanner and dosimeter) was investigated separately prior to full system test. The optical CT scanner has a spatial resolution of {<=}1 mm, geometric accuracy within 1 mm, and high reconstruction linearity (with a R{sup 2} value of 0.9979 and a standard error of estimation of {approx}1%) relative to independent measurement. The overall performance of the PRESAGE trade mark sign /OCTOPUS system was evaluated with respect to a simple known 3D dose distribution, by comparison with GAFCHROMIC[reg] EBT film and the calculated dose from a commissioned planning system. The 'measured' dose distribution in a cylindrical PRESAGE trade mark sign dosimeter (16 cm diameter and 11 cm height) was determined by optical-CT, using a filtered backprojection reconstruction algorithm. A three-way Gamma map comparison (4% dose difference and 4 mm distance to agreement), between the PRESAGE trade mark sign , EBT and calculated dose distributions, showed

Updating and extending the IRDF-2002 dosimetry library

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

Capote, R.; Zolotarev, K.I.; Pronyaev, V.G.

The International Reactor Dosimetry File (IRDF)-2002 released in 2004 by the IAEA (see http://www-nds.iaea.org/irdf2002/) contains cross-section data and corresponding uncertainties for 66 dosimetry reactions. New cross-section evaluations have become available recently that re-define some of these dosimetry reactions including: (1) high-fidelity evaluation work undertaken by one of the authors (KIZ); (2) evaluations from the US ENDF/B-VII.0 and candidate evaluations from the US ENDF/B-VII.1 libraries that cover reactions within the International Evaluation of Neutron Cross-Section Standards; (3) European JEFF3.1 library; and (4) Japanese JENDL-4.0 library. Additional high-threshold reactions not included in IRDF-2002 (e.g., {sup 59C}o(n,3n) and {sup 209}Bi(n,3n)) have been alsomore » evaluated to characterize higher-energy neutron fields. Overall, 37 new evaluations of dosimetry reactions have been assessed and intercomparisons made with integral measurements in reference neutron fields to determine whether they should be adopted to update and improve IRDF-2002. Benchmark calculations performed for newly evaluated reactions using the ENDF/B-VII.0 {sup 235}U thermal fission and {sup 252}Cf spontaneous fission neutron spectra show that calculated integral cross sections exhibit improved agreement with evaluated experimental data when compared with the equivalent data from the IRDF-2002 library. Data inconsistencies or deficiencies of new evaluations have been identified for {sup 63}Cu(n,2n), {sup 60}Ni(n,p) {sup 60m+g}Co, {sup 55}Mn(n,{gamma}), and {sup 232}Th(n,f) reactions. Compared with IRDF-2002, the upper neutron energy boundary was formally increased from the actual maximum energy of typically 20 MeV up to 60 MeV by using the TENDL-2010 cross sections and covariance matrices. This extension would allow the updated IRDF library to be also used in fusion dosimetry applications. Uncertainties in the cross sections for all new evaluations are given in the form

Small field electron beam dosimetry using MOSFET detector

PubMed Central

Heaton, Robert; Norrlinger, Bern; Islam, Mohammad K.

2010-01-01

The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth‐dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. Since modern radiotherapy departments are becoming filmless in favor of electronic imaging, an alternate and readily available clinical dosimeter needs to be explored. We have studied the performance of MOSFET as a relative dosimeter in small field electron beams. The reproducibility, linearity and sensitivity of a high‐sensitivity microMOSFET were investigated for clinical electron beams. In addition, the percent depth doses, output factors and profiles have been measured in a water tank with MOSFET and compared with those measured by an ion chamber for a range of field sizes from 1 cm diameter to 10 cm× 10 cm for 6, 12, 16 and 20 MeV beams. Similar comparative measurements were also performed with MOSFET and films in solid water phantom. The MOSFET sensitivity was found to be practically constant over the range of field sizes investigated. The dose response was found to be linear and reproducible (within ±1% for 100 cGy). An excellent agreement was observed among the central axis depth dose curves measured using MOSFET, film and ion chamber. The output factors measured with MOSFET for small fields agreed to within 3% with those measured by film dosimetry. Overall results indicate that MOSFET can be utilized to perform dosimetry for small field electron beam. PACS number: 87.55.Qr

Small field electron beam dosimetry using MOSFET detector.

PubMed

Amin, Md Nurul; Heaton, Robert; Norrlinger, Bern; Islam, Mohammad K

2010-10-04

The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth-dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. Since modern radiotherapy departments are becoming filmless in favor of electronic imaging, an alternate and readily available clinical dosimeter needs to be explored. We have studied the performance of MOSFET as a relative dosimeter in small field electron beams. The reproducibility, linearity and sensitivity of a high-sensitivity microMOSFET were investigated for clinical electron beams. In addition, the percent depth doses, output factors and profiles have been measured in a water tank with MOSFET and compared with those measured by an ion chamber for a range of field sizes from 1 cm diameter to 10 cm × 10 cm for 6, 12, 16 and 20 MeV beams. Similar comparative measurements were also per-formed with MOSFET and films in solid water phantom. The MOSFET sensitivity was found to be practically constant over the range of field sizes investigated. The dose response was found to be linear and reproducible (within ± 1% for 100 cGy). An excellent agreement was observed among the central axis depth dose curves measured using MOSFET, film and ion chamber. The output factors measured with MOSFET for small fields agreed to within 3% with those measured by film dosimetry. Overall results indicate that MOSFET can be utilized to perform dosimetry for small field electron beam.

Comparison of Organ Dosimetry for Astronaut Phantoms: Earth-Based vs. Microgravity-Based Anthropometry and Body Positioning

NASA Technical Reports Server (NTRS)

VanBaalen, Mary; Bahadon, Amir; Shavers, Mark; Semones, Edward

2011-01-01

The purpose of this study is to use NASA radiation transport codes to compare astronaut organ dose equivalents resulting from solar particle events (SPE), geomagnetically trapped protons, and free-space galactic cosmic rays (GCR) using phantom models representing Earth-based and microgravity-based anthropometry and positioning. Methods: The Univer sity of Florida hybrid adult phantoms were scaled to represent male and female astronauts with 5th, 50th, and 95th percentile heights and weights as measured on Earth. Another set of scaled phantoms, incorporating microgravity-induced changes, such as spinal lengthening, leg volume loss, and the assumption of the neutral body position, was also created. A ray-tracer was created and used to generate body self-shielding distributions for dose points within a voxelized phantom under isotropic irradiation conditions, which closely approximates the free-space radiation environment. Simplified external shielding consisting of an aluminum spherical shell was used to consider the influence of a spacesuit or shielding of a hull. These distributions were combined with depth dose distributions generated from the NASA radiation transport codes BRYNTRN (SPE and trapped protons) and HZETRN (GCR) to yield dose equivalent. Many points were sampled per organ. Results: The organ dos e equivalent rates were on the order of 1.5-2.5 mSv per day for GCR (1977 solar minimum) and 0.4-0.8 mSv per day for trapped proton irradiation with shielding of 2 g cm-2 aluminum equivalent. The organ dose equivalents for SPE irradiation varied considerably, with the skin and eye lens having the highest organ dose equivalents and deep-seated organs, such as the bladder, liver, and stomach having the lowest. Conclus ions: The greatest differences between the Earth-based and microgravity-based phantoms are observed for smaller ray thicknesses, since the most drastic changes involved limb repositioning and not overall phantom size. Improved self-shielding models

Dosimetry of gamma chamber blood irradiator using PAGAT gel dosimeter and Monte Carlo simulations

PubMed Central

Mohammadyari, Parvin; Zehtabian, Mehdi; Sina, Sedigheh; Tavasoli, Ali Reza

2014-01-01

Currently, the use of blood irradiation for inactivating pathogenic microbes in infected blood products and preventing graft‐versus‐host disease (GVHD) in immune suppressed patients is greater than ever before. In these systems, dose distribution and uniformity are two important concepts that should be checked. In this study, dosimetry of the gamma chamber blood irradiator model Gammacell 3000 Elan was performed by several dosimeter methods including thermoluminescence dosimeters (TLD), PAGAT gel dosimetry, and Monte Carlo simulations using MCNP4C code. The gel dosimeter was put inside a glass phantom and the TL dosimeters were placed on its surface, and the phantom was then irradiated for 5 min and 27 sec. The dose values at each point inside the vials were obtained from the magnetic resonance imaging of the phantom. For Monte Carlo simulations, all components of the irradiator were simulated and the dose values in a fine cubical lattice were calculated using tally F6. This study shows that PAGAT gel dosimetry results are in close agreement with the results of TL dosimetry, Monte Carlo simulations, and the results given by the vendor, and the percentage difference between the different methods is less than 4% at different points inside the phantom. According to the results obtained in this study, PAGAT gel dosimetry is a reliable method for dosimetry of the blood irradiator. The major advantage of this kind of dosimetry is that it is capable of 3D dose calculation. PACS number: 87.53.Bn PMID:24423829

Digital Mammography Breast Dosimetry Using Copper-Doped Lithium Fluoride (LiF:MCP) Thermoluminescent Dosimeters (TLDs)

DTIC Science & Technology

2003-06-18

Mammography Breast Dosimetry Using Copper-Doped Lithium Fluoride (LiF:MCP) Thermoluminescent Dosimeters ( TLDs ) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...34Digital Mammography Breast Dosimetry Using Copper- Doped Lithium Fluoride (LiF:MCP) Thermoluminescent Dosimeters ( TLDs )" Author: LT John J. Tomon...Title of Thesis: " Digital Mammography Breast Dosimetry Using Copper-Doped Lithium Fluoride (LiF:MCP) Thermoluminescent

Radiation-induced damage analysed by luminescence methods in retrospective dosimetry and emergency response.

PubMed

Woda, Clemens; Bassinet, Céline; Trompier, François; Bortolin, Emanuela; Della Monaca, Sara; Fattibene, Paola

2009-01-01

The increasing risk of a mass casualty scenario following a large scale radiological accident or attack necessitates the development of appropriate dosimetric tools for emergency response. Luminescence dosimetry has been reliably applied for dose reconstruction in contaminated settlements for several decades and recent research into new materials carried close to the human body opens the possibility of estimating individual doses for accident and emergency dosimetry using the same technique. This paper reviews the luminescence research into materials useful for accident dosimetry and applications in retrospective dosimetry. The properties of the materials are critically discussed with regard to the requirements for population triage. It is concluded that electronic components found within portable electronic devices, such as e.g. mobile phones, are at present the most promising material to function as a fortuitous dosimeter in an emergency response.

SU-F-BRA-11: An Experimental Commissioning Test of Brachytherapy MBDCA Dosimetry, Based On a Commercial Radiochromic Gel/optical CT System

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

Pappas, E; Karaiskos, P; Zourari, K

2015-06-15

Purpose: To implement a 3D dose verification procedure of Model-Based Dose Calculation Algorithms (MBDCAs) for {sup 192}Ir HDR brachytherapy, based on a novel Ferrous Xylenol-orange gel (FXG) and optical CT read-out. Methods: The TruView gel was employed for absolute dosimetry in conjunction with cone-beam optical CT read-out with the VISTA scanner (both from Modus Medical Inc, London, ON, Canada). A multi-catheter skin flap was attached to a cylindrical PETE jar (d=9.6cm, h=16cm) filled with FXG, which served as both the dosimeter and the water equivalent phantom of bounded dimensions. X- ray CT image series of the jar with flap attachedmore » was imported to Oncentra Brachy v.4.5. A treatment plan consisting of 8 catheters and 56 dwell positions was generated, and Oncentra-ACE MBDCA as well as TG43 dose results were exported for further evaluation. The irradiation was carried out with a microSelecton v2 source. The FXG dose-response, measured via an electron irradiation of a second dosimeter from the same batch, was linear (R2>0.999) at least up to 12Gy. A MCNP6 input file was prepared from the DICOM-RT plan data using BrachyGuide to facilitate Monte Carlo (MC) simulation dosimetry in the actual experimental geometry. Agreement between experimental (reference) and calculated dose distributions was evaluated using the 3D gamma index (GI) method with criteria (5%-2mm applied locally) determined from uncertainty analysis. Results: The TG-43 GI failed, as expected, in the majority of voxels away from the flap (pass rate 59% for D>0.8Gy, corresponding to 10% of prescribed dose). ACE performed significantly better (corresponding pass rate 92%). The GI evaluation for the MC data (corresponding pass rate 97%) failed mainly at low dose points of increased uncertainty. Conclusion: FXG gel/optical CT is an efficient method for level-2 commissioning of brachytherapy MBDCAs. Target dosimetry is not affected from uncertainty introduced by TG43 assumptions in 192Ir skin

RADON PROGENY AS AN EXPERIMENTAL TOOL FOR DOSIMETRY OF NANOAEROSOLS

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

Ruzer, Lev; Ruzer, Lev S.; Apte, Michael G.

2008-02-25

The study of aerosol exposure and dosimetry measurements and related quantitation of health effects are important to the understanding of the consequences of air pollution, and are discussed widely in the scientific literature. During the last 10 years the need to correlate aerosol exposure and biological effects has become especially important due to rapid development of a new, revolutionary industry ?-- nanotechnology. Nanoproduct commerce is predicted to top $1 trillion by 2015. Quantitative assessment of aerosol particle behavior in air and in lung deposition, and dosimetry in different parts of the lung, particularly for nanoaerosols, remains poor despite several decadesmore » of study. Direct measurements on humans are still needed in order to validate the hollow cast, animal studies, and lung deposition modeling. We discuss here the use of nanoscale radon decay products as an experimental tool in the study of local deposition and lung dosimetry for nanoaerosols. The issue of the safe use of radon progeny in such measurements is discussed based on a comparison of measured exposure in 3 settings: general population, miners, and in a human experiment conducted at the Paul Scherer Institute (PSI) in Switzerland. One of the properties of radon progeny is that they consist partly of 1 nm radioactive particles called unattached activity; having extremely small size and high diffusion coefficients, these particles can be potentially useful as radioactive tracers in the study of nanometer-sized aerosols. We present a theoretical and experimental study of the correlation between the unattached activity and aerosol particle surface area, together with a description of its calibration and method for measurement of the unattached fraction.« less

In vivo dosimetry in external beam radiotherapy.

PubMed

Mijnheer, Ben; Beddar, Sam; Izewska, Joanna; Reft, Chester

2013-07-01

In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20∕20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

Anthropomorphic Phantom Radiation Dosimetry at the NATO Standard Reference Point at Aberdeen Proving Ground,

DTIC Science & Technology

1987-04-01

and would still be well under 10(C. .% % p., I V a- E p - -12 - IABLE 8 (a) TLD results for phantom dosimetry - all values shown are measured charge...SAI. Conclusions The current DREO dosimetry system-consisting of bubble, CR39 and TLD dosimeters - has proven capable of producing meaningful results at...MC FILE CoPy’ Defence nationale 00 ANTHROPOMORPHIC PHANTOM RADIATION DOSIMETRY AT THE NATO STANDARD OREFERENCE POINT AT ABERDEEN PROVING GROUND by T

A comprehensive tool for image-based generation of fetus and pregnant women mesh models for numerical dosimetry studies

NASA Astrophysics Data System (ADS)

Dahdouh, S.; Varsier, N.; Serrurier, A.; De la Plata, J.-P.; Anquez, J.; Angelini, E. D.; Wiart, J.; Bloch, I.

2014-08-01

Fetal dosimetry studies require the development of accurate numerical 3D models of the pregnant woman and the fetus. This paper proposes a 3D articulated fetal growth model covering the main phases of pregnancy and a pregnant woman model combining the utero-fetal structures and a deformable non-pregnant woman body envelope. The structures of interest were automatically or semi-automatically (depending on the stage of pregnancy) segmented from a database of images and surface meshes were generated. By interpolating linearly between fetal structures, each one can be generated at any age and in any position. A method is also described to insert the utero-fetal structures in the maternal body. A validation of the fetal models is proposed, comparing a set of biometric measurements to medical reference charts. The usability of the pregnant woman model in dosimetry studies is also investigated, with respect to the influence of the abdominal fat layer.

Methods and Models of the Hanford Internal Dosimetry Program, PNNL-MA-860

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

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2009-09-30

The Hanford Internal Dosimetry Program (HIDP) provides internal dosimetry support services for operations at the Hanford Site. The HIDP is staffed and managed by the Radiation and Health Technology group, within the Pacific Northwest National Laboratory (PNNL). Operations supported by the HIDP include research and development, the decontamination and decommissioning of facilities formerly used to produce and purify plutonium, and waste management activities. Radioelements of particular interest are plutonium, uranium, americium, tritium, and the fission and activation product radionuclides 137Cs, 90Sr, and 60Co. This manual describes the technical basis for the design of the routine bioassay monitoring program and formore » assessment of internal dose. The purposes of the manual are as follows: • Provide assurance that the HIDP derives from a sound technical base. • Promote the consistency and continuity of routine program activities. • Provide a historical record. • Serve as a technical reference for radiation protection personnel. • Aid in identifying and planning for future needs.« less

Synthesis and characterization of luminescent materials for thermal sensing and proton dosimetry

NASA Astrophysics Data System (ADS)

Doull, Brandon Arthur

The work presented in this thesis is the materials synthesis, investigation of synthesis parameters, and basic luminescent characterizations of MgB 4O7, Li2B4O7, and MgO for the applications of thermal sensing using thermoluminescence (TL) and proton dosimetry using optically stimulated luminescence (OSL). The materials were synthesized using solution combustion synthesis and characterized by x-ray diffraction, radioluminescence, thermoluminescence, and optically stimulated luminescence. Based upon the basic characterizations MgB 4O7:Li,Dy and Li2B4O7:Cu,Ag were selected for their potential for use as TL materials for thermal sensing while MgB4O7:Li,Ce and MgO:Li were chosen for use as OSL materials in proton dosimetry. Furthermore, MgB4O7:Li,Ce and MgO:Li were fabricated into detector assemblies and exposed to a clinical proton beam for analysis.

Methods and Models of the Hanford Internal Dosimetry Program, PNNL-MA-860

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

Carbaugh, Eugene H.; Bihl, Donald E.; Maclellan, Jay A.

2003-01-03

This manual describes the technical basis for the design of the routine radiobioassay monitoring program and assessments of internal dose. Its purpose is to provide a historical record of the methods, models, and assumptions used for internal dosimetry at Hanford, and serve as a technical reference for radiation protection and dosimetry staff.

A Novel Technique for Performing Space Based Radiation Dosimetry Using DNA-Results from GRaDEx-I and the Design of GRaDEx-II

NASA Technical Reports Server (NTRS)

Ritter, Joe; Branly, R.; Theodorakis, C.; Bickham, J.; Swartz, C.; Friedfeld, R.; Ackerman, E.; Carruthers, C.; DiGirolamo, A.; Faranda, J.

1999-01-01

Because of the large amounts of cosmic radiation in the space environment relative to that on earth, the effects of radiation on the physiology of astronauts is of major concern. Doses of radiation which can cause acute or chronic biological effects are to be avoided, therefore determination of the amount of radiation exposure encountered during space flight and assessment of its impact on biological systems is critical. Quantifying the radiation dosage and damage to biological systems, especially to humans during repetitive high altitude flight and during long duration space flight is important for several reasons. Radiation can cause altered biosynthesis and long term genotoxicity resulting in cancer and birth defects etc. Radiation damage to biological systems depends in a complex way on incident radiation species and their energy spectra. Typically non-biological, i.e. film or electronic monitoring systems with narrow energy band sensitivity are used to perform dosimetry and then results are extrapolated to biological models. For this reason it may be desirable to perform radiation dosimetry by using biological molecules e.g. DNA or RNA strands as passive sensors. A lightweight genotoxicology experiment was constructed to determine the degree to which in vitro naked DNA extracted from tissues of a variety of vertebrate organisms is damaged by exposure to radiation in a space environment. The DNA is assayed by means of agarose gel electrophoresis to determine damage such as strand breakage caused by high momentum particles and photons, and base oxidation caused by free radicals. The length distribution of DNA fragments is directly correlated with the radiation dose. It is hoped that a low mass, low cost, passive biological system to determine dose response relationship (increase in strand breaks with increase in exposure) can be developed to perform radiation dosimetry in support of long duration space flight, and to predict negative effects on biological

A Novel Technique for Performing Space Based Radiation Dosimetry Using DNA: Results from GRaDEx-I and the Design of GRaDEx-II

NASA Technical Reports Server (NTRS)

Ritter, Joe; Branly, R.; Theodorakis, C.; Bickham, J.; Swartz, C.; Friedfeld, R.; Ackerman, E.; Carruthers, C.; DiGirolamo, A.; Faranda, J.;

Impact of PET and MRI threshold-based tumor volume segmentation on patient-specific targeted radionuclide therapy dosimetry using CLR1404.

PubMed

Besemer, Abigail E; Titz, Benjamin; Grudzinski, Joseph J; Weichert, Jamey P; Kuo, John S; Robins, H Ian; Hall, Lance T; Bednarz, Bryan P

2017-07-06

Variations in tumor volume segmentation methods in targeted radionuclide therapy (TRT) may lead to dosimetric uncertainties. This work investigates the impact of PET and MRI threshold-based tumor segmentation on TRT dosimetry in patients with primary and metastatic brain tumors. In this study, PET/CT images of five brain cancer patients were acquired at 6, 24, and 48 h post-injection of 124 I-CLR1404. The tumor volume was segmented using two standardized uptake value (SUV) threshold levels, two tumor-to-background ratio (TBR) threshold levels, and a T1 Gadolinium-enhanced MRI threshold. The dice similarity coefficient (DSC), jaccard similarity coefficient (JSC), and overlap volume (OV) metrics were calculated to compare differences in the MRI and PET contours. The therapeutic 131 I-CLR1404 voxel-level dose distribution was calculated from the 124 I-CLR1404 activity distribution using RAPID, a Geant4 Monte Carlo internal dosimetry platform. The TBR, SUV, and MRI tumor volumes ranged from 2.3-63.9 cc, 0.1-34.7 cc, and 0.4-11.8 cc, respectively. The average  ±  standard deviation (range) was 0.19  ±  0.13 (0.01-0.51), 0.30  ±  0.17 (0.03-0.67), and 0.75  ±  0.29 (0.05-1.00) for the JSC, DSC, and OV, respectively. The DSC and JSC values were small and the OV values were large for both the MRI-SUV and MRI-TBR combinations because the regions of PET uptake were generally larger than the MRI enhancement. Notable differences in the tumor dose volume histograms were observed for each patient. The mean (standard deviation) 131 I-CLR1404 tumor doses ranged from 0.28-1.75 Gy GBq -1 (0.07-0.37 Gy GBq -1 ). The ratio of maximum-to-minimum mean doses for each patient ranged from 1.4-2.0. The tumor volume and the interpretation of the tumor dose is highly sensitive to the imaging modality, PET enhancement metric, and threshold level used for tumor volume segmentation. The large variations in tumor doses clearly demonstrate the need for

Impact of PET and MRI threshold-based tumor volume segmentation on patient-specific targeted radionuclide therapy dosimetry using CLR1404

NASA Astrophysics Data System (ADS)

Besemer, Abigail E.; Titz, Benjamin; Grudzinski, Joseph J.; Weichert, Jamey P.; Kuo, John S.; Robins, H. Ian; Hall, Lance T.; Bednarz, Bryan P.

2017-08-01

Variations in tumor volume segmentation methods in targeted radionuclide therapy (TRT) may lead to dosimetric uncertainties. This work investigates the impact of PET and MRI threshold-based tumor segmentation on TRT dosimetry in patients with primary and metastatic brain tumors. In this study, PET/CT images of five brain cancer patients were acquired at 6, 24, and 48 h post-injection of 124I-CLR1404. The tumor volume was segmented using two standardized uptake value (SUV) threshold levels, two tumor-to-background ratio (TBR) threshold levels, and a T1 Gadolinium-enhanced MRI threshold. The dice similarity coefficient (DSC), jaccard similarity coefficient (JSC), and overlap volume (OV) metrics were calculated to compare differences in the MRI and PET contours. The therapeutic 131I-CLR1404 voxel-level dose distribution was calculated from the 124I-CLR1404 activity distribution using RAPID, a Geant4 Monte Carlo internal dosimetry platform. The TBR, SUV, and MRI tumor volumes ranged from 2.3-63.9 cc, 0.1-34.7 cc, and 0.4-11.8 cc, respectively. The average  ±  standard deviation (range) was 0.19  ±  0.13 (0.01-0.51), 0.30  ±  0.17 (0.03-0.67), and 0.75  ±  0.29 (0.05-1.00) for the JSC, DSC, and OV, respectively. The DSC and JSC values were small and the OV values were large for both the MRI-SUV and MRI-TBR combinations because the regions of PET uptake were generally larger than the MRI enhancement. Notable differences in the tumor dose volume histograms were observed for each patient. The mean (standard deviation) 131I-CLR1404 tumor doses ranged from 0.28-1.75 Gy GBq-1 (0.07-0.37 Gy GBq-1). The ratio of maximum-to-minimum mean doses for each patient ranged from 1.4-2.0. The tumor volume and the interpretation of the tumor dose is highly sensitive to the imaging modality, PET enhancement metric, and threshold level used for tumor volume segmentation. The large variations in tumor doses clearly demonstrate the need for standard

Freeware for reporting radiation dosimetry following the administration of radiopharmaceuticals.

PubMed

Gómez Perales, Jesús Luis; García Mendoza, Antonio

2015-09-01

This work describes the development of a software application for reporting patient radiation dosimetry following radiopharmaceutical administration. The resulting report may be included within the patient's medical records. The application was developed in the Visual Basic programming language. The dosimetric calculations are based on the values given by the International Commission on Radiological Protection (ICRP). The software is available in both Spanish and English and can be downloaded at no cost from www.radiopharmacy.net. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dosimetry for photo-coagulation by the use of autofluorescence

NASA Astrophysics Data System (ADS)

Brodzinski, T.

1989-01-01

A basic problem when using lasers in medicine is that of dosimetry. The definition of the terms dose, effective value etc. will be dealt with in Chapter 2. This chapter is intended to give an insight into the problems of basic dosimetry and its technical realization within the field of photocoagulation, an established method used to treat the retina, or some skin diseases. Until now the coagulation process was assessed to be completed when the irradiated area became blanched. However in terms of dosimetry, it must be possible to predict or at least to monitor the biological effect using well-defined parameters for the laser or in achieving an objective measure for a feedback loop. In the case of coagulation, a prediction in this form is not possible. There are two ways of pro- ceeding further see Fig. 1. One can either determine the physical effect, i.e. temperature, by some kind of sensors, or even better, use some biological effect as a direct measure of the effective dose applied.

Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams.

PubMed

Sánchez-Doblado, F; Andreo, P; Capote, R; Leal, A; Perucha, M; Arráns, R; Núñez, L; Mainegra, E; Lagares, J I; Carrasco, E

2003-07-21

Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm2 beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix (delta = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm2 fields. For radiosurgery applicators and narrow MLC beams, the calculated s(w,air) values agree with the reference within +/-0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s(w,air) agrees within 0.1% with the value for 10 x 10 cm2, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24 MV) the difference in s

Improved dosimetry techniques for intravascular brachytherapy

NASA Astrophysics Data System (ADS)

Sehgal, Varun

Coronary artery disease leads to the accumulation of atheromatous plaque leading to coronary stenosis. Coronary intervention techniques such as balloon angioplasty and atherectomy are used to address coronary stenosis and establish a stable lumen thus enhancing blood flow to the myocardium. Restenosis or re-blockage of the arteries is a major limitation of the above mentioned interventional techniques. Neointimal hyperplasia or proliferation of cells in response to the vascular injury as a result of coronary intervention is considered to be one of the major causes of restenosis. Recent studies indicated that irradiation of the coronary lesion site, with radiation doses ranging from 15 to 30 Gy, leads to diminishing neointimal hyperplasia with subsequent reduction in restenosis. The radiation dose is given by catheter-based radiation delivery systems using beta-emitters 90Sr/90Y, 32P and gamma-emitting 192Ir among others. However the dose schema used for dose prescription for these sources are relatively simplistic, and are based on calculations using uniform homogenous water or tissue media and simple cylinder geometry. Stenotic coronary vessels are invariably lined with atheromatous plaque of heterogeneous composition, the radiation dose distribution obtained from such dosimetry data can cause significant variations in the actual dose received by a given patient. Such discrepancies in dose calculation can introduce relatively large uncertainties in the limits of dose window for effective and safe application of intravascular brachytherapy, and consequently in the clinical evaluation of the efficacy of this modality. In this research study we investigated the effect of different geometrical and material heterogeneities, including residual plaque, catheter non-centering, lesion eccentricity and cardiac motion on the radiation dose delivered at the lesion site. Correction factors including dose perturbation factors and dose variation factors have been calculated

Fourth conference on radiation protection and dosimetry: Proceedings, program, and abstracts

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

Casson, W.H.; Thein, C.M.; Bogard, J.S.

This Conference is the fourth in a series of conferences organized by staff members of Oak Ridge National Laboratory in an effort to improve communication in the field of radiation protection and dosimetry. Scientists, regulators, managers, professionals, technologists, and vendors from the United States and countries around the world have taken advantage of this opportunity to meet with their contemporaries and peers in order to exchange information and ideas. The program includes over 100 papers in 9 sessions, plus an additional session for works in progress. Papers are presented in external dosimetry, internal dosimetry, radiation protection programs and assessments, developmentsmore » in instrumentation and materials, environmental and medical applications, and on topics related to standards, accreditation, and calibration. Individual papers are indexed separately on EDB.« less

Absorbed radiation dosimetry of the D3-specific PET radioligand [18F]FluorTriopride estimated using rodent and nonhuman primate.

PubMed

Laforest, Richard; Karimi, Morvarid; Moerlein, Stephen M; Xu, Jinbin; Flores, Hubert P; Bognar, Christopher; Li, Aixiao; Mach, Robert H; Perlmutter, Joel S; Tu, Zhude

2016-01-01

[ 18 F]FluorTriopride ([ 18 F]FTP) is a dopamine D 3 -receptor preferring radioligand with potential for investigation of neuropsychiatric disorders including Parkinson disease, dystonia and schizophrenia. Here we estimate human radiation dosimetry for [ 18 F]FTP based on the ex-vivo biodistribution in rodents and in vivo distribution in nonhuman primates. Biodistribution data were generated using male and female Sprague-Dawley rats injected with ~370 KBq of [ 18 F]FTP and euthanized at 5, 30, 60, 120, and 240 min. Organs of interest were dissected, weighed and assayed for radioactivity content. PET imaging studies were performed in two male and one female macaque fascicularis administered 143-190 MBq of [ 18 F]FTP and scanned whole-body in sequential sections. Organ residence times were calculated based on organ time activity curves (TAC) created from regions of Interest. OLINDA/EXM 1.1 was used to estimate human radiation dosimetry based on scaled organ residence times. In the rodent, the highest absorbed radiation dose was the upper large intestines (0.32-0.49 mGy/MBq), with an effective dose of 0.07 mSv/MBq in males and 0.1 mSv/MBq in females. For the nonhuman primate, however, the gallbladder wall was the critical organ (1.81 mGy/MBq), and the effective dose was 0.02 mSv/MBq. The species discrepancy in dosimetry estimates for [ 18 F]FTP based on rat and primate data can be attributed to the slower transit of tracer through the hepatobiliary track of the primate compared to the rat, which lacks a gallbladder. Out findings demonstrate that the nonhuman primate model is more appropriate model for estimating human absorbed radiation dosimetry when hepatobiliary excretion plays a major role in radiotracer elimination.

Absorbed radiation dosimetry of the D3-specific PET radioligand [18F]FluorTriopride estimated using rodent and nonhuman primate

PubMed Central

Laforest, Richard; Karimi, Morvarid; Moerlein, Stephen M; Xu, Jinbin; Flores, Hubert P; Bognar, Christopher; Li, Aixiao; Mach, Robert H; Perlmutter, Joel S; Tu, Zhude

2016-01-01

[18F]FluorTriopride ([18F]FTP) is a dopamine D3-receptor preferring radioligand with potential for investigation of neuropsychiatric disorders including Parkinson disease, dystonia and schizophrenia. Here we estimate human radiation dosimetry for [18F]FTP based on the ex-vivo biodistribution in rodents and in vivo distribution in nonhuman primates. Biodistribution data were generated using male and female Sprague-Dawley rats injected with ~370 KBq of [18F]FTP and euthanized at 5, 30, 60, 120, and 240 min. Organs of interest were dissected, weighed and assayed for radioactivity content. PET imaging studies were performed in two male and one female macaque fascicularis administered 143-190 MBq of [18F]FTP and scanned whole-body in sequential sections. Organ residence times were calculated based on organ time activity curves (TAC) created from regions of Interest. OLINDA/EXM 1.1 was used to estimate human radiation dosimetry based on scaled organ residence times. In the rodent, the highest absorbed radiation dose was the upper large intestines (0.32-0.49 mGy/MBq), with an effective dose of 0.07 mSv/MBq in males and 0.1 mSv/MBq in females. For the nonhuman primate, however, the gallbladder wall was the critical organ (1.81 mGy/MBq), and the effective dose was 0.02 mSv/MBq. The species discrepancy in dosimetry estimates for [18F]FTP based on rat and primate data can be attributed to the slower transit of tracer through the hepatobiliary track of the primate compared to the rat, which lacks a gallbladder. Out findings demonstrate that the nonhuman primate model is more appropriate model for estimating human absorbed radiation dosimetry when hepatobiliary excretion plays a major role in radiotracer elimination. PMID:28078183

Shared dosimetry error in epidemiological dose-response analyses

DOE PAGES

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail; ...

2015-03-23

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of "possible" dose history to workers given dose determinants. This paper takesmore » up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. The use of these methods in the context of several studies including, the Mayak Worker Cohort, and the U.S. Atomic Veterans Study, is discussed.« less

Shared Dosimetry Error in Epidemiological Dose-Response Analyses

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

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail

2015-03-23

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of "possible" dose history to workers given dose determinants. This paper takesmore » up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. Use of these methods for several studies, including the Mayak Worker Cohort and the U.S. Atomic Veterans Study, is discussed.« less

Study of The Non-linear Uv Dosimetry In Simulated Extraterrestrial Conditions

NASA Astrophysics Data System (ADS)

Berces, A.; Kerekgyarto, T.; Ronto, G.; Lammer, H.; Kargl, G.; Komle, N. I.

In UV biological dosimetry the UV dose scale is additive starting at a value of zero ac- cording to the definition of CIE (Technical Report TC-6-18). The biological dose can be defined by a measured end-effect. In our dosimeters (phage T7 and uracil dosime- ter) exposed to natural (terrestrial) UV radiation the proportion of pyrimidin photo- products among the total photoproducts is smaller than 10 and the linear correlation between the biological and physical dose is higher than 0.9. According to the experi- mental data this linear relationship is often not valid. We observed that UV radiation did not only induce dimerisation but shorter wavelengths caused monomerisation of pyrimidin dimers. Performing the irradiation in oxygen free environment and using a Deuterium lamp as UV source, we could increase monomerisation against dimerisa- tion thus the DNA-based dosimetrySs additivity rule is not fulfilled in these conditions. In this study we will demonstrate those non-linear experiments which constitute the basis of our biological experiments on the International Space Station.

Air density correction in ionization dosimetry.

PubMed

Christ, G; Dohm, O S; Schüle, E; Gaupp, S; Martin, M

2004-05-21

Air density must be taken into account when ionization dosimetry is performed with unsealed ionization chambers. The German dosimetry protocol DIN 6800-2 states an air density correction factor for which current barometric pressure and temperature and their reference values must be known. It also states that differences between air density and the attendant reference value, as well as changes in ionization chamber sensitivity, can be determined using a radioactive check source. Both methods have advantages and drawbacks which the paper discusses in detail. Barometric pressure at a given height above sea level can be determined by using a suitable barometer, or data downloaded from airport or weather service internet sites. The main focus of the paper is to show how barometric data from measurement or from the internet are correctly processed. Therefore the paper also provides all the requisite equations and terminological explanations. Computed and measured barometric pressure readings are compared, and long-term experience with air density correction factors obtained using both methods is described.

Episcleral eye plaque dosimetry comparison for the Eye Physics EP917 using Plaque Simulator and Monte Carlo simulation

PubMed Central

Amoush, Ahmad; Wilkinson, Douglas A.

2015-01-01

This work is a comparative study of the dosimetry calculated by Plaque Simulator, a treatment planning system for eye plaque brachytherapy, to the dosimetry calculated using Monte Carlo simulation for an Eye Physics model EP917 eye plaque. Monte Carlo (MC) simulation using MCNPX 2.7 was used to calculate the central axis dose in water for an EP917 eye plaque fully loaded with 17 IsoAid Advantage  125I seeds. In addition, the dosimetry parameters Λ, gL(r), and F(r,θ) were calculated for the IsoAid Advantage model IAI‐125  125I seed and benchmarked against published data. Bebig Plaque Simulator (PS) v5.74 was used to calculate the central axis dose based on the AAPM Updated Task Group 43 (TG‐43U1) dose formalism. The calculated central axis dose from MC and PS was then compared. When the MC dosimetry parameters for the IsoAid Advantage  125I seed were compared with the consensus values, Λ agreed with the consensus value to within 2.3%. However, much larger differences were found between MC calculated gL(r) and F(r,θ) and the consensus values. The differences between MC‐calculated dosimetry parameters are much smaller when compared with recently published data. The differences between the calculated central axis absolute dose from MC and PS ranged from 5% to 10% for distances between 1 and 12 mm from the outer scleral surface. When the dosimetry parameters for the  125I seed from this study were used in PS, the calculated absolute central axis dose differences were reduced by 2.3% from depths of 4 to 12 mm from the outer scleral surface. We conclude that PS adequately models the central dose profile of this plaque using its defaults for the IsoAid model IAI‐125 at distances of 1 to 7 mm from the outer scleral surface. However, improved dose accuracy can be obtained by using updated dosimetry parameters for the IsoAid model IAI‐125  125I seed. PACS number: 87.55.K‐ PMID:26699577

Time resolved dosimetry of human brain exposed to low frequency pulsed magnetic fields.

PubMed

Paffi, Alessandra; Camera, Francesca; Lucano, Elena; Apollonio, Francesca; Liberti, Micaela

2016-06-21

An accurate dosimetry is a key issue to understanding brain stimulation and related interaction mechanisms with neuronal tissues at the basis of the increasing amount of literature revealing the effects on human brain induced by low-level, low frequency pulsed magnetic fields (PMFs). Most literature on brain dosimetry estimates the maximum E field value reached inside the tissue without considering its time pattern or tissue dispersivity. Nevertheless a time-resolved dosimetry, accounting for dispersive tissues behavior, becomes necessary considering that the threshold for an effect onset may vary depending on the pulse waveform and that tissues may filter the applied stimulatory fields altering the predicted stimulatory waveform's size and shape. In this paper a time-resolved dosimetry has been applied on a realistic brain model exposed to the signal presented in Capone et al (2009 J. Neural Transm. 116 257-65), accounting for the broadband dispersivity of brain tissues up to several kHz, to accurately reconstruct electric field and current density waveforms inside different brain tissues. The results obtained by exposing the Duke's brain model to this PMF signal show that the E peak in the brain is considerably underestimated if a simple monochromatic dosimetry is carried out at the pulse repetition frequency of 75 Hz.

Time resolved dosimetry of human brain exposed to low frequency pulsed magnetic fields

NASA Astrophysics Data System (ADS)

Paffi, Alessandra; Camera, Francesca; Lucano, Elena; Apollonio, Francesca; Liberti, Micaela

2016-06-01

An accurate dosimetry is a key issue to understanding brain stimulation and related interaction mechanisms with neuronal tissues at the basis of the increasing amount of literature revealing the effects on human brain induced by low-level, low frequency pulsed magnetic fields (PMFs). Most literature on brain dosimetry estimates the maximum E field value reached inside the tissue without considering its time pattern or tissue dispersivity. Nevertheless a time-resolved dosimetry, accounting for dispersive tissues behavior, becomes necessary considering that the threshold for an effect onset may vary depending on the pulse waveform and that tissues may filter the applied stimulatory fields altering the predicted stimulatory waveform’s size and shape. In this paper a time-resolved dosimetry has been applied on a realistic brain model exposed to the signal presented in Capone et al (2009 J. Neural Transm. 116 257-65), accounting for the broadband dispersivity of brain tissues up to several kHz, to accurately reconstruct electric field and current density waveforms inside different brain tissues. The results obtained by exposing the Duke’s brain model to this PMF signal show that the E peak in the brain is considerably underestimated if a simple monochromatic dosimetry is carried out at the pulse repetition frequency of 75 Hz.

Hanford Technical Basis for Multiple Dosimetry Effective Dose Methodology

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

Hill, Robin L.; Rathbone, Bruce A.

2010-08-01

The current method at Hanford for dealing with the results from multiple dosimeters worn during non-uniform irradiation is to use a compartmentalization method to calculate the effective dose (E). The method, as documented in the current version of Section 6.9.3 in the 'Hanford External Dosimetry Technical Basis Manual, PNL-MA-842,' is based on the compartmentalization method presented in the 1997 ANSI/HPS N13.41 standard, 'Criteria for Performing Multiple Dosimetry.' With the adoption of the ICRP 60 methodology in the 2007 revision to 10 CFR 835 came changes that have a direct affect on the compartmentalization method described in the 1997 ANSI/HPS N13.41more » standard, and, thus, to the method used at Hanford. The ANSI/HPS N13.41 standard committee is in the process of updating the standard, but the changes to the standard have not yet been approved. And, the drafts of the revision of the standard tend to align more with ICRP 60 than with the changes specified in the 2007 revision to 10 CFR 835. Therefore, a revised method for calculating effective dose from non-uniform external irradiation using a compartmental method was developed using the tissue weighting factors and remainder organs specified in 10 CFR 835 (2007).« less

Accidental neutron dosimetry with human hair

NASA Astrophysics Data System (ADS)

Ekendahl, Daniela; Bečková, Věra; Zdychová, Vlasta; Bulánek, Boris; Prouza, Zdeněk; Štefánik, Milan

2014-11-01

Human hair contains sulfur, which can be activated by fast neutrons. The 32S(n,p)32P reaction with a threshold of 2.5 MeV was used for fast neutron dose estimation. It is a very important parameter for individual dose reconstruction with regards to the heterogeneity of the neutron transfer to the human body. Samples of human hair were irradiated in a radial channel of a training reactor VR-1. 32P activity in hair was measured both, directly by means of a proportional counter, and as ash dispersed in a liquid scintillator. Based on neutron spectrum estimation, a relationship between the neutron dose and induced activity was derived. The experiment verified the practical feasibility of this dosimetry method in cases of criticality accidents or malevolent acts with nuclear materials.

Commissioning dosimetry and in situ dose mapping of a semi-industrial Cobalt-60 gamma-irradiation facility using Fricke and Ceric-cerous dosimetry system and comparison with Monte Carlo simulation data

NASA Astrophysics Data System (ADS)

Mortuza, Md Firoz; Lepore, Luigi; Khedkar, Kalpana; Thangam, Saravanan; Nahar, Arifatun; Jamil, Hossen Mohammad; Bandi, Laxminarayan; Alam, Md Khorshed

2018-03-01

Characterization of a 90 kCi (3330 TBq), semi-industrial, cobalt-60 gamma irradiator was performed by commissioning dosimetry and in-situ dose mapping experiments with Ceric-cerous and Fricke dosimetry systems. Commissioning dosimetry was carried out to determine dose distribution pattern of absorbed dose in the irradiation cell and products. To determine maximum and minimum absorbed dose, overdose ratio and dwell time of the tote boxes, homogeneous dummy product (rice husk) with a bulk density of 0.13 g/cm3 were used in the box positions of irradiation chamber. The regions of minimum absorbed dose of the tote boxes were observed in the lower zones of middle plane and maximum absorbed doses were found in the middle position of front plane. Moreover, as a part of dose mapping, dose rates in the wall positions and some selective strategic positions were also measured to carry out multiple irradiation program simultaneously, especially for low dose research irradiation program. In most of the cases, Monte Carlo simulation data, using Monte Carlo N-Particle eXtended code version MCNPX 2.7., were found to be in congruence with experimental values obtained from Ceric-cerous and Fricke dosimetry; however, in close proximity positions from the source, the dose rate variation between chemical dosimetry and MCNP was higher than distant positions.

SU-F-T-262: Commissioning Varian Portal Dosimetry for EPID-Based Patient Specific QA in a Non-Aria Environment

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

Schmidt, M; Knutson, N; University of Rhode Island, Kingston, RI

2016-06-15

Purpose: Development of an in-house program facilitates a workflow that allows Electronic Portal Imaging Device (EPID) patient specific quality assurance (QA) measurements to be acquired and analyzed in the Portal Dosimetry Application (Varian Medical Systems, Palo Alto, CA) using a non-Aria Record and Verify (R&V) system (MOSAIQ, Elekta, Crawley, UK) to deliver beams in standard clinical treatment mode. Methods: Initial calibration of an in-house software tool includes characterization of EPID dosimetry parameters by importing DICOM images of varying delivered MUs to determine linear mapping factors in order to convert image pixel values to Varian-defined Calibrated Units (CU). Using this information,more » the Portal Dose Image Prediction (PDIP) algorithm was commissioned by converting images of various field sizes to output factors using the Eclipse Scripting Application Programming Interface (ESAPI) and converting a delivered configuration fluence to absolute dose units. To verify the algorithm configuration, an integrated image was acquired, exported directly from the R&V client, automatically converted to a compatible, calibrated dosimetric image, and compared to a PDIP calculated image using Varian’s Portal Dosimetry Application. Results: For two C-Series and one TrueBeam Varian linear accelerators, gamma comparisons (global 3% / 3mm) of PDIP algorithm predicted dosimetric images and images converted via the inhouse system demonstrated agreement for ≥99% of all pixels, exceeding vendor-recommended commissioning guidelines. Conclusion: Combinations of a programmatic image conversion tool and ESAPI allow for an efficient and accurate method of patient IMRT QA incorporating a 3rd party R&V system.« less

Design of the free-air ionization chamber, FAC-IR-150, for X-ray dosimetry

NASA Astrophysics Data System (ADS)

Mohammadi, Seyed Mostafa; Tavakoli-Anbaran, Hossein

2018-03-01

The primary standard for X-ray dosimetry is based on the free-air ionization chamber (FAC). Therefore, the Atomic Energy Organization of Iran (AEOI) designed the free-air ionization chamber, FAC-IR-150, for low and medium energy X-ray dosimetry. The purpose of this work is the study of the free-air ionization chamber characteristics and the design of the FAC-IR-150. The FAC-IR-150 dosimeter has two parallel plates, a high voltage plate and a collector plate. A guard electrode surrounds the collector and is separated by an air gap. A group of guard strips is used between up and down electrodes to produce a uniform electric field in all the ion chamber volume. This design involves introducing the correction factors and determining the exact dimensions of the ionization chamber by using Monte Carlo simulation.

An image-based skeletal dosimetry model for the ICRP reference adult male—internal electron sources

NASA Astrophysics Data System (ADS)

Hough, Matthew; Johnson, Perry; Rajon, Didier; Jokisch, Derek; Lee, Choonsik; Bolch, Wesley

2011-04-01

In this study, a comprehensive electron dosimetry model of the adult male skeletal tissues is presented. The model is constructed using the University of Florida adult male hybrid phantom of Lee et al (2010 Phys. Med. Biol. 55 339-63) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow, associated with radiogenic leukemia, and total shallow marrow, associated with radiogenic bone cancer. Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following sources: bone marrow (active and inactive), trabecular bone (surfaces and volumes), and cortical bone (surfaces and volumes). Specific absorbed fractions are computed according to the MIRD schema, and are given as skeletal-averaged values in the paper with site-specific values reported in both tabular and graphical format in an electronic annex available from http://stacks.iop.org/0031-9155/56/2309/mmedia. The distribution of cortical bone and spongiosa at the macroscopic dimensions of the phantom, as well as the distribution of trabecular bone and marrow tissues at the microscopic dimensions of the phantom, is imposed through detailed analyses of whole-body ex vivo CT images (1 mm resolution) and spongiosa-specific ex vivo microCT images (30 µm resolution), respectively, taken from a 40 year male cadaver. The method utilized in this work includes: (1) explicit accounting for changes in marrow self-dose with variations in marrow cellularity, (2) explicit accounting for electron escape from spongiosa, (3) explicit consideration of spongiosa cross-fire from cortical bone, and (4) explicit consideration of the ICRP's change in the surrogate tissue region defining the location of the osteoprogenitor cells (from a 10 µm endosteal layer covering the trabecular and cortical surfaces to a 50 µm shallow marrow layer covering trabecular and medullary cavity surfaces). Skeletal

Understanding the potentiality of accelerator based-boron neutron capture therapy for osteosarcoma: dosimetry assessment based on the reported clinical experience.

PubMed

Bortolussi, Silva; Postuma, Ian; Protti, Nicoletta; Provenzano, Lucas; Ferrari, Cinzia; Cansolino, Laura; Dionigi, Paolo; Galasso, Olimpio; Gasparini, Giorgio; Altieri, Saverio; Miyatake, Shin-Ichi; González, Sara J

2017-08-15

Osteosarcoma is the most frequent primary malignant bone tumour, and its incidence is higher in children and adolescents, for whom it represents more than 10% of solid cancers. Despite the introduction of adjuvant and neo-adjuvant chemotherapy that markedly increased the success rate in the treatment, aggressive surgery is still needed and a considerable percentage of patients do not survive due to recurrences or early metastases. Boron Neutron Capture Therapy (BNCT), an experimental radiotherapy, was investigated as a treatment that could allow a less aggressive surgery by killing infiltrated tumour cells in the surrounding healthy tissues. BNCT requires an intense neutron beam to ensure irradiation times of the order of 1 h. In Italy, a Radio Frequency Quadrupole (RFQ) proton accelerator has been designed and constructed for BNCT, and a suitable neutron spectrum was tailored by means of Monte Carlo calculations. This paper explores the feasibility of BNCT to treat osteosarcoma using this neutron source based on accelerator. The therapeutic efficacy of BNCT was analysed evaluating the dose distribution obtained in a clinical case of femur osteosarcoma. Mixed field dosimetry was assessed with two different formalisms whose parameters were specifically derived from radiobiological experiments involving in vitro UMR-106 osteosarcoma cell survival assays and boron concentration assessments in an animal model of osteosarcoma. A clinical case of skull osteosarcoma treated with BNCT in Japan was re-evaluated from the point of view of dose calculation and used as a reference for comparison. The results in the case of femur osteosarcoma show that the RFQ beam would ensure a suitable tumour dose painting in a total irradiation time of less than an hour. Comparing the dosimetry between the analysed case and the treated patient in Japan it turns out that doses obtained in the femur tumour are at least as good as the ones delivered in the skull osteosarcoma. The same is

Patient-specific dosimetry based on quantitative SPECT imaging and 3D-DFT convolution

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

Akabani, G.; Hawkins, W.G.; Eckblade, M.B.

1999-01-01

The objective of this study was to validate the use of a 3-D discrete Fourier Transform (3D-DFT) convolution method to carry out the dosimetry for I-131 for soft tissues in radioimmunotherapy procedures. To validate this convolution method, mathematical and physical phantoms were used as a basis of comparison with Monte Carlo transport (MCT) calculations which were carried out using the EGS4 system code. The mathematical phantom consisted of a sphere containing uniform and nonuniform activity distributions. The physical phantom consisted of a cylinder containing uniform and nonuniform activity distributions. Quantitative SPECT reconstruction was carried out using the Circular Harmonic Transformmore » (CHT) algorithm.« less

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

NASA Astrophysics Data System (ADS)

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

2010-11-01

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

Commissioning of a well type chamber for HDR and LDR brachytherapy applications: a review of methodology and outcomes.

PubMed

Mukwada, Godfrey; Neveri, Gabor; Alkhatib, Zaid; Waterhouse, David K; Ebert, Martin

2016-03-01

For safe and accurate dose delivery in brachytherapy, associated equipment is subject to commissioning and ongoing quality assurance (QA). Many centres depend on the use of a well-type chamber ('well chamber') for performing brachytherapy dosimetry. Documentation of well chamber commissioning is scarce despite the important role the chamber plays in the whole brachytherapy QA process. An extensive and structured commissioning of the HDR 1000 plus well chamber (Standard Imaging Inc, Middleton WI) for HDR and LDR dosimetry was undertaken at Sir Charles Gairdner Hospital. The methodology and outcomes of this commissioning is documented and presented as a guideline to others involved in brachytherapy. The commissioning tests described include mechanical integrity, leakage current, directional dependence, response, length of uniform response, the influence of insert holders, ion collection efficiency, polarity effect, accuracy of measured air kerma strength (S(K)) or reference air kerma rate (K(R)) and baseline setting (for ongoing constancy checks). For the HDR 1000 plus well chamber, some of the insert holders modify the response curve. The measured sweet length was 2.5 cm which is within 0.5% of that specified by the manufacturer. Correction for polarity was negligible (0.9999) and ion recombination was small (0.9994). Directional dependence was small (less than 0.2%) and leakage current was negligible. The measured K(R) for (192)Ir agreed within 0.11% compared with a second well chamber of similar model and was within 0.5% of that determined via a free-in-air measurement method. Routine constancy checks over a year agreed with the baseline within 0.4%.

Critical dosimetry measures and surrogate tools that can facilitate clinical success in PDT (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pogue, Brian W.; Davis, Scott C.; Kanick, Stephen C.; Maytin, Edward V.; Pereira, Stephen P.; Palanisami, Akilan; Hasan, Tayyaba

2016-03-01

Photodynamic therapy can be a highly complex treatment with more than one parameter to control, or in some cases it is easily implemented with little control other than prescribed drug and light values. The role of measured dosimetry as related to clinical adoption has not been as successful as it could have been, and part of this may be from the conflicting goals of advocating for as many measurements as possible for accurate control, versus companies and clinical adopters advocating for as few measurements as possible, to keep it simple. An organized approach to dosimetry selection is required, which shifts from mechanistic measurements in pre-clinical and early phase I trials, towards just those essential dose limiting measurements and a focus on possible surrogate measures in phase II/III trials. This essential and surrogate approach to dosimetry should help successful adoption of clinical PDT if successful. The examples of essential dosimetry points and surrogate dosimetry tools which might be implemented in phase II and higher trials are discussed for solid tissue PDT with verteporfin and skin lesion treatment with aminolevulinc acid.

SU-F-T-367: Using PRIMO, a PENELOPE-Based Software, to Improve the Small Field Dosimetry of Linear Accelerators

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

Benmakhlouf, H; Andreo, P; Brualla, L

2016-06-15

Purpose: To calculate output correction factors for Varian Clinac 2100iX beams for seven small field detectors and use the values to determine the small field output factors for the linacs at Karolinska university hospital. Methods: Phase space files (psf) for square fields between 0.25cm and 10cm were calculated using the PENELOPE-based PRIMO software. The linac MC-model was tuned by comparing PRIMO-estimated and experimentally determined depth doses and lateral dose-profiles for 40cmx40cm fields. The calculated psf were used as radiation sources to calculate the correction factors of IBA and PTW detectors with the code penEasy/PENELOPE. Results: The optimal tuning parameters ofmore » the MClinac model in PRIMO were 5.4 MeV incident electron energy and zero energy spread, focal spot size and beam divergence. Correction factors obtained for the liquid ion chamber (PTW-T31018) are within 1% down to 0.5 cm fields. For unshielded diodes (IBA-EFD, IBA-SFD, PTW-T60017 and PTW-T60018) the corrections are up to 2% at intermediate fields (>1cm side), becoming down to −11% for fields smaller than 1cm. The shielded diode (IBA-PFD and PTW-T60016) corrections vary with field size from 0 to −4%. Volume averaging effects are found for most detectors in the presence of 0.25cm fields. Conclusion: Good agreement was found between correction factors based on PRIMO-generated psf and those from other publications. The calculated factors will be implemented in output factor measurements (using several detectors) in the clinic. PRIMO is a userfriendly general code capable of generating small field psf and can be used without having to code own linac geometries. It can therefore be used to improve the clinical dosimetry, especially in the commissioning of linear accelerators. Important dosimetry data, such as dose-profiles and output factors can be determined more accurately for a specific machine, geometry and setup by using PRIMO and having a MC-model of the detector used.« less

RENEB - Running the European Network of biological dosimetry and physical retrospective dosimetry.

PubMed

Kulka, Ulrike; Abend, Michael; Ainsbury, Elizabeth; Badie, Christophe; Barquinero, Joan Francesc; Barrios, Lleonard; Beinke, Christina; Bortolin, Emanuela; Cucu, Alexandra; De Amicis, Andrea; Domínguez, Inmaculada; Fattibene, Paola; Frøvig, Anne Marie; Gregoire, Eric; Guogyte, Kamile; Hadjidekova, Valeria; Jaworska, Alicja; Kriehuber, Ralf; Lindholm, Carita; Lloyd, David; Lumniczky, Katalin; Lyng, Fiona; Meschini, Roberta; Mörtl, Simone; Della Monaca, Sara; Monteiro Gil, Octávia; Montoro, Alegria; Moquet, Jayne; Moreno, Mercedes; Oestreicher, Ursula; Palitti, Fabrizio; Pantelias, Gabriel; Patrono, Clarice; Piqueret-Stephan, Laure; Port, Matthias; Prieto, María Jesus; Quintens, Roel; Ricoul, Michelle; Romm, Horst; Roy, Laurence; Sáfrány, Géza; Sabatier, Laure; Sebastià, Natividad; Sommer, Sylwester; Terzoudi, Georgia; Testa, Antonella; Thierens, Hubert; Turai, Istvan; Trompier, François; Valente, Marco; Vaz, Pedro; Voisin, Philippe; Vral, Anne; Woda, Clemens; Zafiropoulos, Demetre; Wojcik, Andrzej

2017-01-01

A European network was initiated in 2012 by 23 partners from 16 European countries with the aim to significantly increase individualized dose reconstruction in case of large-scale radiological emergency scenarios. The network was built on three complementary pillars: (1) an operational basis with seven biological and physical dosimetric assays in ready-to-use mode, (2) a basis for education, training and quality assurance, and (3) a basis for further network development regarding new techniques and members. Techniques for individual dose estimation based on biological samples and/or inert personalized devices as mobile phones or smart phones were optimized to support rapid categorization of many potential victims according to the received dose to the blood or personal devices. Communication and cross-border collaboration were also standardized. To assure long-term sustainability of the network, cooperation with national and international emergency preparedness organizations was initiated and links to radiation protection and research platforms have been developed. A legal framework, based on a Memorandum of Understanding, was established and signed by 27 organizations by the end of 2015. RENEB is a European Network of biological and physical-retrospective dosimetry, with the capacity and capability to perform large-scale rapid individualized dose estimation. Specialized to handle large numbers of samples, RENEB is able to contribute to radiological emergency preparedness and wider large-scale research projects.

Use of the FLUKA Monte Carlo code for 3D patient-specific dosimetry on PET-CT and SPECT-CT images*

PubMed Central

Botta, F; Mairani, A; Hobbs, R F; Vergara Gil, A; Pacilio, M; Parodi, K; Cremonesi, M; Coca Pérez, M A; Di Dia, A; Ferrari, M; Guerriero, F; Battistoni, G; Pedroli, G; Paganelli, G; Torres Aroche, L A; Sgouros, G

2014-01-01

Patient-specific absorbed dose calculation for nuclear medicine therapy is a topic of increasing interest. 3D dosimetry at the voxel level is one of the major improvements for the development of more accurate calculation techniques, as compared to the standard dosimetry at the organ level. This study aims to use the FLUKA Monte Carlo code to perform patient-specific 3D dosimetry through direct Monte Carlo simulation on PET-CT and SPECT-CT images. To this aim, dedicated routines were developed in the FLUKA environment. Two sets of simulations were performed on model and phantom images. Firstly, the correct handling of PET and SPECT images was tested under the assumption of homogeneous water medium by comparing FLUKA results with those obtained with the voxel kernel convolution method and with other Monte Carlo-based tools developed to the same purpose (the EGS-based 3D-RD software and the MCNP5-based MCID). Afterwards, the correct integration of the PET/SPECT and CT information was tested, performing direct simulations on PET/CT images for both homogeneous (water) and non-homogeneous (water with air, lung and bone inserts) phantoms. Comparison was performed with the other Monte Carlo tools performing direct simulation as well. The absorbed dose maps were compared at the voxel level. In the case of homogeneous water, by simulating 108 primary particles a 2% average difference with respect to the kernel convolution method was achieved; such difference was lower than the statistical uncertainty affecting the FLUKA results. The agreement with the other tools was within 3–4%, partially ascribable to the differences among the simulation algorithms. Including the CT-based density map, the average difference was always within 4% irrespective of the medium (water, air, bone), except for a maximum 6% value when comparing FLUKA and 3D-RD in air. The results confirmed that the routines were properly developed, opening the way for the use of FLUKA for patient-specific, image-based

Field monitoring versus individual miner dosimetry of radon daughter products in mines.

PubMed

Domański, T; Kluszczyński, D; Olszewski, J; Chruscielewski, W

1989-01-01

The paper presents the results realised simultaneously by two different and independent systems of measurement of an assessment of miners' exposure to radon daughter products which naturally occur in the air of mines. The first one, called the Air Sampling System (ASS), was based on the field monitoring of radon progeny in air, the second one, called the Individual Dosimetry System (IDS), was based on the individual dosimeters worn by miners. Experimental comparison of these two systems has been conducted for six years in eleven Polish underground metal-ore mines. This study reveals that no correlation exists between the concentration and annual miners' exposures evaluated by the ASS and IDS. The ratio ASS/IDS for mine population varies from 11.0 to 0.14 in respect of annual concentration means, and in respect to annual exposures, this ratio varies from 4.5 to 0.14. The conclusion to be drawn from six years' observation and comparison of both systems is that correct and true evaluation of miners' exposure to radon progeny can be made only by the use of the Individual Dosimetry System, since the Air Sampling System is too sensitive and too dependent on the Strategy of sampling and its radiation.

Benefits of online in vivo dosimetry for single-fraction total body irradiation

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

Eaton, David J., E-mail: davideaton@nhs.net; Warry, Alison J.; Trimble, Rachel E.

Use of a patient test dose before single-fraction total body irradiation (TBI) allows review of in vivo dosimetry and modification of the main treatment setup. However, use of computed tomography (CT) planning and online in vivo dosimetry may reduce the need for this additional step. Patients were treated using a supine CT-planned extended source-to-surface distance (SSD) technique with lead compensators and bolus. In vivo dosimetry was performed using thermoluminescent dosimeters (TLDs) and diodes at 10 representative anatomical locations, for both a 0.1-Gy test dose and the treatment dose. In total, 28 patients were treated between April 2007 and July 2013,more » with changes made in 10 cases (36%) following test dose results. Overall, 98.1% of measured in vivo treatment doses were within 10% of the prescribed dose, compared with 97.0% of test dose readings. Changes made following the test dose could have been applied during the single-fraction treatment itself, assuming that the dose was delivered in subportions and online in vivo dosimetry was available for all clinically important anatomical sites. This alleviates the need for a test dose, saving considerable time and resources.« less

Thyroid cancer following scalp irradiation: a reanalysis accounting for uncertainty in dosimetry.

PubMed

Schafer, D W; Lubin, J H; Ron, E; Stovall, M; Carroll, R J

2001-09-01

In the 1940s and 1950s, over 20,000 children in Israel were treated for tinea capitis (scalp ringworm) by irradiation to induce epilation. Follow-up studies showed that the radiation exposure was associated with the development of malignant thyroid neoplasms. Despite this clear evidence of an effect, the magnitude of the dose-response relationship is much less clear because of probable errors in individual estimates of dose to the thyroid gland. Such errors have the potential to bias dose-response estimation, a potential that was not widely appreciated at the time of the original analyses. We revisit this issue, describing in detail how errors in dosimetry might occur, and we develop a new dose-response model that takes the uncertainties of the dosimetry into account. Our model for the uncertainty in dosimetry is a complex and new variant of the classical multiplicative Berkson error model, having components of classical multiplicative measurement error as well as missing data. Analysis of the tinea capitis data suggests that measurement error in the dosimetry has only a negligible effect on dose-response estimation and inference as well as on the modifying effect of age at exposure.

Prediction and evaluation of route dependent dosimetry of BPA in rats at different life stages using a physiologically based pharmacokinetic model

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

Yang, Xiaoxia, E-mail: Xiaoxia.Yang@fda.hhs.gov; Doerge, Daniel R.; Fisher, Jeffrey W.

Bisphenol A (BPA) has received considerable attention throughout the last decade due to its widespread use in consumer products. For the first time a physiologically based pharmacokinetic (PBPK) model was developed in neonatal and adult rats to quantitatively evaluate age-dependent pharmacokinetics of BPA and its phase II metabolites. The PBPK model was calibrated in adult rats using studies on BPA metabolism and excretion in the liver and gastrointestinal tract, and pharmacokinetic data with BPA in adult rats. For immature rats the hepatic and gastrointestinal metabolism of BPA was inferred from studies on the maturation of phase II enzymes coupled withmore » serum time course data in pups. The calibrated model predicted the measured serum concentrations of BPA and BPA conjugates after administration of 100 μg/kg of d6-BPA in adult rats (oral gavage and intravenous administration) and postnatal days 3, 10, and 21 pups (oral gavage). The observed age-dependent BPA serum concentrations were partially attributed to the immature metabolic capacity of pups. A comparison of the dosimetry of BPA across immature rats and monkeys suggests that dose adjustments would be necessary to extrapolate toxicity studies from neonatal rats to infant humans. - Highlights: • A PBPK model predicts the kinetics of bisphenol A (BPA) in young and adult rats. • BPA metabolism within enterocytes is required for fitting of oral BPA kinetic data. • BPA dosimetry in young rats is different than adult rats and young monkeys.« less

TLD and OSLD dosimetry systems for remote audits of radiotherapy external beam calibration.

PubMed

Alvarez, P; Kry, S F; Stingo, F; Followill, D

2017-11-01

The Imaging and Radiation Oncology Core QA Center in Houston (IROC-H) performs remote dosimetry audits of more than 20,000 megavoltage photon and electron beams each year. Both a thermoluminescent dosimeter (TLD-100) and optically stimulated luminescent dosimeter (OSLD; nanoDot) system are commissioned for this task, with the OSLD system being predominant due to the more time-efficient read-out process. The measurement apparatus includes 3 TLD or 2 OSLD in an acrylic mini-phantom, which are irradiated by the institution under reference geometry. Dosimetry systems are calibrated based on the signal-to-dose conversion established with reference dosimeters irradiated in a Co-60 beam, using a reference dose of 300 cGy for TLD and 100 cGy for OSLD. The uncertainty in the dose determination is 1.3% for TLD and 1.6% for OSLD at the one sigma level. This accuracy allows for a tolerance of ±5% to be used.

On the use of unshielded cables in ionization chamber dosimetry for total-skin electron therapy.

PubMed

Chen, Z; Agostinelli, A; Nath, R

1998-03-01

The dosimetry of total-skin electron therapy (TSET) usually requires ionization chamber measurements in a large electron beam (up to 120 cm x 200 cm). Exposing the chamber's electric cable, its connector and part of the extension cable to the large electron beam will introduce unwanted electronic signals that may lead to inaccurate dosimetry results. While the best strategy to minimize the cable-induced electronic signal is to shield the cables and its connector from the primary electrons, as has been recommended by the AAPM Task Group Report 23 on TSET, cables without additional shielding are often used in TSET dosimetry measurements for logistic reasons, for example when an automatic scanning dosimetry is used. This paper systematically investigates the consequences and the acceptability of using an unshielded cable in ionization chamber dosimetry in a large TSET electron beam. In this paper, we separate cable-induced signals into two types. The type-I signal includes all charges induced which do not change sign upon switching the chamber polarity, and type II includes all those that do. The type-I signal is easily cancelled by the polarity averaging method. The type-II cable-induced signal is independent of the depth of the chamber in a phantom and its magnitude relative to the true signal determines the acceptability of a cable for use under unshielded conditions. Three different cables were evaluated in two different TSET beams in this investigation. For dosimetry near the depth of maximum buildup, the cable-induced dosimetry error was found to be less than 0.2% when the two-polarity averaging technique was applied. At greater depths, the relative dosimetry error was found to increase at a rate approximately equal to the inverse of the electron depth dose. Since the application of the two-polarity averaging technique requires a constant-irradiation condition, it was demonstrated than an additional error of up to 4% could be introduced if the unshielded cable

Comparison of dose response functions for EBT3 model GafChromic™ film dosimetry system.

PubMed

Aldelaijan, Saad; Devic, Slobodan

2018-05-01

Different dose response functions of EBT3 model GafChromic™ film dosimetry system have been compared in terms of sensitivity as well as uncertainty vs. error analysis. We also made an assessment of the necessity of scanning film pieces before and after irradiation. Pieces of EBT3 film model were irradiated to different dose values in Solid Water (SW) phantom. Based on images scanned in both reflection and transmission mode before and after irradiation, twelve different response functions were calculated. For every response function, a reference radiochromic film dosimetry system was established by generating calibration curve and by performing the error vs. uncertainty analysis. Response functions using pixel values from the green channel demonstrated the highest sensitivity in both transmission and reflection mode. All functions were successfully fitted with rational functional form, and provided an overall one-sigma uncertainty of better than 2% for doses above 2 Gy. Use of pre-scanned images to calculate response functions resulted in negligible improvement in dose measurement accuracy. Although reflection scanning mode provides higher sensitivity and could lead to a more widespread use of radiochromic film dosimetry, it has fairly limited dose range and slightly increased uncertainty when compared to transmission scan based response functions. Double-scanning technique, either in transmission or reflection mode, shows negligible improvement in dose accuracy as well as a negligible increase in dose uncertainty. Normalized pixel value of the images scanned in transmission mode shows linear response in a dose range of up to 11 Gy. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Radiation dosimetry estimates of (18)F-alfatide II based on whole-body PET imaging of mice.

PubMed

Wang, Si-Yang; Bao, Xiao; Wang, Ming-Wei; Zhang, Yong-Ping; Zhang, Ying-Jian; Zhang, Jian-Ping

2015-11-01

We estimated the dosimetry of (18)F-alfatide II with the method established by MIRD based on biodistribution data of mice. Six mice (three females and three males) were scanned for 160min on an Inveon MicroPET/CT scanner after injection of (18)F-alfatide II via tail vein. Eight source organs were delineated on the CT images and their residence times calculated. The data was then converted to human using scaling factors based on organ and body weight. The absorbed doses for human and the resulting effective dose were computed by OLINDA 1.1 software. The highest absorbed doses was observed in urinary bladder wall (male 0.102mGy/MBq, female 0.147mGy/MBq); and the lowest one was detected in brain (male 0.0030mGy/MBq, female 0.0036). The total effective doses were 0.0127mSv/MBq for male and 0.0166 mSv/MBq for female, respectively. A 370-MBq injection of (18)F-alfatide II led to an estimated effective dose of 4.70mSv for male and 6.14mSv for female. The potential radiation burden associated with (18)F-alfatide II/PET imaging therefore is comparable to other PET examinations. Copyright © 2015 Elsevier Ltd. All rights reserved.

TU-H-CAMPUS-TeP2-03: High Sensitivity and High Resolution Fiber Based Micro-Detector for Sub-Millimeter Preclinical Dosimetry

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

Izaguirre, E; Pokhrel, S; Knewtson, T

2016-06-15

Purpose: Current precision of small animal and cell micro-irradiators has continuously increased during the past years. Currently, preclinical irradiators can deliver sub-millimeter fields with micrometric precision but there are no water equivalent dosimeters to determine small field profiles and dose in the orthovoltage range of energies with micrometric resolution and precision. We have developed a fiber based micro-dosimeter with the resolution and dosimetric accuracy required for radiobiological research. Methods: We constructed two prototypes of micro-dosimeters based on different compositions of fiber scintillators to study the spatial resolution and dosimetric precision of small animal and cell micro-irradiators. The first has greenmore » output and the second has blue output. The blue output dosimeter has the highest sensitivity because it matches the spectral sensitivity of silicon photomultipliers. A blue detector with 500um cross section was built and tested respect to a CC01 ion chamber, film, and the 1500um green output detector. Orthovoltage fields from 1×1mm2 to 5×5mm2 were used for detector characteristics comparison. Results: The blue fiber dosimeter shows great agreement with films and matches dose measurements with the gold-standard ion chamber for 5×5mm2 fields. The detector has the appropriate sensitivity to measure fields from 1×1mm2 to larger sizes with a 1% dosimetric accuracy. The spatial resolution is in the sub-millimeter range and the spectral matching with the photomultiplier allows reducing the sensor cross section even further than the presented prototype. These results suggest that scintillating fibers combined with silicon photomultipliers is the appropriate technology to pursue micro-dosimetry for small animals and disperse cell samples. Conclusion: The constructed detectors establish a new landmark for the resolution and sensitivity of fiber based microdetectors. The validation of the detector in our small animal and cell

In Vitro Exposure Systems and Dosimetry Assessment Tools ...

EPA Pesticide Factsheets

In 2009, the passing of The Family Smoking Prevention and Tobacco Control Act facilitated the establishment of the FDA Center for Tobacco Products (CTP) and gave it regulatory authority over the marketing, manufacture and distribution of tobacco products, including those termed “modified risk”. On 4-6 April 2016, the Institute for In Vitro Sciences, Inc. (IIVS) convened a workshop conference titled “In Vitro Exposure Systems and Dosimetry Assessment Tools for Inhaled Tobacco Products” to bring together stakeholders representing regulatory agencies, academia, and industry to address the research priorities articulated by the FDA CTP. Specific topics were covered to assess the status of current in vitro smoke and aerosol/vapor exposure systems, as well as the various approaches and challenges to quantifying the complex exposures, in in vitro pulmonary models developed for evaluating adverse pulmonary events resulting from tobacco product exposures. The four core topics covered were, 1) Tobacco Smoke And E-Cigarette Aerosols, 2) Air-Liquid Interface-In Vitro Exposure Systems, 3) Dosimetry Approaches For Particles And Vapors; In Vitro Dosimetry Determinations and 4) Exposure Microenvironment/Physiology Of Cells. The two and a half day workshop included presentations from 20 expert speakers, poster sessions, networking discussions, and breakout sessions which identified key findings and provided recommendations to advance these technologies. Here, we will re

Considerations regarding the implementation of EPR dosimetry for the population in the vicinity of Semipalatinsk nuclear test site based on experience from other radiation accidents.

PubMed

Skvortsov, Valeriy; Ivannikov, Alexander; Tikunov, Dimitri; Stepanenko, Valeriy; Borysheva, Natalie; Orlenko, Sergey; Nalapko, Mikhail; Hoshi, Masaharu

2006-02-01

General aspects of applying the method of retrospective dose estimation by electron paramagnetic resonance spectroscopy of human tooth enamel (EPR dosimetry) to the population residing in the vicinity of the Semipalatinsk nuclear test site are analyzed and summarized. The analysis is based on the results obtained during 20 years of investigations conducted in the Medical Radiological Research Center regarding the development and practical application of this method for wide-scale dosimetrical investigation of populations exposed to radiation after the Chernobyl accident and other radiation accidents.

Korean standard nuclear plant ex-vessel neutron dosimetry program Ulchin 4

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

Duo, J.I.; Chen, J.; Kulesza, J.A.

2011-07-01

A comprehensive ex-vessel neutron dosimetry (EVND) surveillance program has been deployed in 16 pressurized water reactors (PWR) in South Korea and EVND dosimetry sets have already been installed and analyzed in Westinghouse reactor designs. In this paper, the unique features of the design, training, and installation in the Korean standard nuclear plant (KSNP) Ulchin Unit 4 are presented. Ulchin Unit 4 Cycle 9 represents the first dosimetry analyzed from the EVND design deployed in KSNP plants: Yonggwang Units 3 through 6 and Ulchin Units 3 through 6. KSNP's cavity configuration precludes a conventional installation from the cavity floor. The solution,more » requiring the installation crew to access the cavity at an elevation of the active core, places a premium on rapid installation due to high area dose rates. Numerous geometrical features warranted the use of a detailed design in true 3D mechanical design software to control interferences. A full-size training mockup maximized the crew ability to correctly install the instrument in minimum time. The analysis of the first dosimetry set shows good agreements between measurement and calculation within the associated uncertainties. A complete EVND system has been successfully designed, installed, and analyzed for a KNSP plant. Current and future EVND analyses will continue supporting the successful operation of PWR units in South Korea. (authors)« less

A comparison of two methods of in vivo dosimetry for a high energy neutron beam.

PubMed

Blake, S W; Bonnett, D E; Finch, J

1990-06-01

Two methods of in vivo dosimetry have been compared in a high energy neutron beam. These were activation dosimetry and thermoluminescence dosimetry (TLD). Their suitability was determined by comparison with estimates of total dose, obtained using a tissue equivalent ionization chamber. Measurements were made on the central axis and a profile of a 10 x 10 cm square field and also behind a shielding block in order to simulate conditions of clinical use. The TLD system was found to provide the best estimate of total dose.

In vivo light dosimetry for pleural PDT

NASA Astrophysics Data System (ADS)

Dimofte, Andreea; Zhu, Timothy C.; Finlay, Jarod C.; Culligan, Melissa; Edmonds, Christine E.; Friedberg, Joseph S.; Cengel, Keith; Hahn, Stephen M.

2009-02-01

In-vivo light Dosimetry for patients undergoing photodynamic therapy (PDT) is one of the important dosimetry quantities critical for predicting PDT outcome. This study examines the light fluence (rate) delivered to patients undergoing pleural PDT as a function of treatment time, treatment volume and surface area, and its accuracy as a function of the calibration accuracies of each isotropic detector and the calibration integrating sphere. The patients studied here were enrolled in Phase II clinical trial of Photofrin-mediated PDT for the treatment of non-small cell lung cancer with pleural effusion. The ages of the patients studied varied from 34 to 69 year old. All patients were administered 2mg per kg body weight Photoprin 24 hours before the surgery. Patients undergoing photodynamic therapy (PDT) are treated with laser light with a light fluence of 60 J/cm^2 at 630nm. Fluence rate (mW/cm^2) and cumulative fluence (J/cm^2) was monitored at 7 different sites during the entire light treatment delivery. Isotropic detectors were used for in-vivo light dosimetry. The anisotropy of each isotropic detector was found to be within 30%. The mean fluence rate delivery varied from 37.84 to 94.05 mW/cm^2 and treatment time varied from 1762 to 5232s. We have established a correlation between the treatment time and the treatment volume. The results are discussed using an integrating sphere theory and the measured tissue optical properties. The result can be used as a clinical guideline for future pleural PDT treatment.

SU-E-T-624: Quantitative Evaluation of 2D Versus 3D Dosimetry for Stereotactic Volumetric Modulated Arc Delivery Using COMPASS

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

Vikraman, S; Karrthick, K; Rajesh, T

2014-06-15

Purpose: The purpose of this study was to evaluate quantitatively 2D versus 3D dosimetry for stereotactic volumetric modulated arc delivery using COMPASS with 2D array. Methods: Twenty-five patients CT images and RT structures of different sites like brain, head and neck, thorax, abdomen and spine were taken from Multiplan planning system for this study. All these patients underwent radical stereotactic treatment in Cyberknife. For each patient, linac based VMAT stereotactic plans were generated in Monaco TPS v 3.1 using Elekta Beam Modulator MLC. Dose prescription was in the range of 5-20Gy/fraction.TPS calculated VMAT plan delivery accuracy was quantitatively evaluated withmore » COMPASS measured dose and calculated dose based on DVH metrics. In order to ascertain the potential of COMPASS 3D dosimetry for stereotactic plan delivery, 2D fluence verification was performed with MatriXX using Multicube. Results: For each site, D{sub 9} {sub 5} was achieved with 100% of prescription dose with maximum 0.05SD. Conformity index (CI) was observed closer to 1.15 in all cases. Maximum deviation of 2.62 % was observed for D{sub 9} {sub 5} when compared TPS versus COMPASS measured. Considerable deviations were observed in head and neck cases compare to other sites. The maximum mean and standard deviation for D{sub 9} {sub 5}, average target dose and average gamma were -0.78±1.72, -1.10±1.373 and 0.39±0.086 respectively. Numbers of pixels passing 2D fluence verification were observed as a mean of 99.36% ±0.455 SD with 3% dose difference and 3mm DTA. For critical organs in head and neck cases, significant dose differences were observed in 3D dosimetry while the target doses were matched well within limit in both 2D and 3D dosimetry. Conclusion: The quantitative evaluations of 2D versus 3D dosimetry for stereotactic volumetric modulated plans showed the potential of highlighting the delivery errors. This study reveals that COMPASS 3D dosimetry is an effective tool for

A Quality Assurance Method that Utilizes 3D Dosimetry and Facilitates Clinical Interpretation

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

Oldham, Mark, E-mail: mark.oldham@duke.edu; Thomas, Andrew; O'Daniel, Jennifer

2012-10-01

Purpose: To demonstrate a new three-dimensional (3D) quality assurance (QA) method that provides comprehensive dosimetry verification and facilitates evaluation of the clinical significance of QA data acquired in a phantom. Also to apply the method to investigate the dosimetric efficacy of base-of-skull (BOS) intensity-modulated radiotherapy (IMRT) treatment. Methods and Materials: Two types of IMRT QA verification plans were created for 6 patients who received BOS IMRT. The first plan enabled conventional 2D planar IMRT QA using the Varian portal dosimetry system. The second plan enabled 3D verification using an anthropomorphic head phantom. In the latter, the 3D dose distribution wasmore » measured using the DLOS/Presage dosimetry system (DLOS = Duke Large-field-of-view Optical-CT System, Presage Heuris Pharma, Skillman, NJ), which yielded isotropic 2-mm data throughout the treated volume. In a novel step, measured 3D dose distributions were transformed back to the patient's CT to enable calculation of dose-volume histograms (DVH) and dose overlays. Measured and planned patient DVHs were compared to investigate clinical significance. Results: Close agreement between measured and calculated dose distributions was observed for all 6 cases. For gamma criteria of 3%, 2 mm, the mean passing rate for portal dosimetry was 96.8% (range, 92.0%-98.9%), compared to 94.9% (range, 90.1%-98.9%) for 3D. There was no clear correlation between 2D and 3D passing rates. Planned and measured dose distributions were evaluated on the patient's anatomy, using DVH and dose overlays. Minor deviations were detected, and the clinical significance of these are presented and discussed. Conclusions: Two advantages accrue to the methods presented here. First, treatment accuracy is evaluated throughout the whole treated volume, yielding comprehensive verification. Second, the clinical significance of any deviations can be assessed through the generation of DVH curves and dose overlays on the

Advances in Inhalation Dosimetry Models and Methods for Occupational Risk Assessment and Exposure Limit Derivation

PubMed Central

Kuempel, Eileen D.; Sweeney, Lisa M.; Morris, John B.; Jarabek, Annie M.

2015-01-01

The purpose of this article is to provide an overview and practical guide to occupational health professionals concerning the derivation and use of dose estimates in risk assessment for development of occupational exposure limits (OELs) for inhaled substances. Dosimetry is the study and practice of measuring or estimating the internal dose of a substance in individuals or a population. Dosimetry thus provides an essential link to understanding the relationship between an external exposure and a biological response. Use of dosimetry principles and tools can improve the accuracy of risk assessment, and reduce the uncertainty, by providing reliable estimates of the internal dose at the target tissue. This is accomplished through specific measurement data or predictive models, when available, or the use of basic dosimetry principles for broad classes of materials. Accurate dose estimation is essential not only for dose-response assessment, but also for interspecies extrapolation and for risk characterization at given exposures. Inhalation dosimetry is the focus of this paper since it is a major route of exposure in the workplace. Practical examples of dose estimation and OEL derivation are provided for inhaled gases and particulates. PMID:26551218

The specifics of dosimetry for food irradiation applications

NASA Astrophysics Data System (ADS)

Kuntz, Florent; Strasser, Alain

2016-12-01

Dose measurement applied to food irradiation is obviously a very important and critical aspect of this process. It is described in many standards and guides. The application of appropriate dosimetry tools is explained. This helps to ensure traceability of this measurement and number of dosimeters available on the market are well studied even though theirs response should be characterized while used in routine processing conditions. When employed in low energy radiation fields, these dosimeters may exhibit specific response compared to the usual Cobalt 60 source irradiation. Traceable calibration or correction factor assessment of this energy dependency is mandatory. It is to mention that the absorbed dose is measured in the dosimeter itself and unfortunately not in/on the food product. However, existing dosimetry systems fulfill all relevant requirements.

Dosimetry audits and intercomparisons in radiotherapy: A Malaysian profile

NASA Astrophysics Data System (ADS)

M. Noor, Noramaliza; Nisbet, A.; Hussein, M.; Chu S, Sarene; Kadni, T.; Abdullah, N.; Bradley, D. A.

2017-11-01

Quality audits and intercomparisons are important in ensuring control of processes in any system of endeavour. Present interest is in control of dosimetry in teletherapy, there being a need to assess the extent to which there is consistent radiation dose delivery to the patient. In this study we review significant factors that impact upon radiotherapy dosimetry, focusing upon the example situation of radiotherapy delivery in Malaysia, examining existing literature in support of such efforts. A number of recommendations are made to provide for increased quality assurance and control. In addition to this study, the first level of intercomparison audit i.e. measuring beam output under reference conditions at eight selected Malaysian radiotherapy centres is checked; use being made of 9 μm core diameter Ge-doped silica fibres (Ge-9 μm). The results of Malaysian Secondary Standard Dosimetry Laboratory (SSDL) participation in the IAEA/WHO TLD postal dose audit services during the period between 2011 and 2015 will also been discussed. In conclusion, following review of the development of dosimetry audits and the conduct of one such exercise in Malaysia, it is apparent that regular periodic radiotherapy audits and intercomparison programmes should be strongly supported and implemented worldwide. The programmes to-date demonstrate these to be a good indicator of errors and of consistency between centres. A total of ei+ght beams have been checked in eight Malaysian radiotherapy centres. One out of the eight beams checked produced an unacceptable deviation; this was found to be due to unfamiliarity with the irradiation procedures. Prior to a repeat measurement, the mean ratio of measured to quoted dose was found to be 0.99 with standard deviation of 3%. Subsequent to the repeat measurement, the mean distribution was 1.00, and the standard deviation was 1.3%.

Patient dose analysis in total body irradiation through in vivo dosimetry.

PubMed

Ganapathy, K; Kurup, P G G; Murali, V; Muthukumaran, M; Bhuvaneshwari, N; Velmurugan, J

2012-10-01

Total body irradiation (TBI) is a special radiotherapy technique, administered prior to bone marrow transplantation. Due to the complex nature of the treatment setup, in vivo dosimetry for TBI is mandatory to ensure proper delivery of the intended radiation dose throughout the body. Lithium fluoride (LiF) TLD-100 chips are used for the TBI in vivo dosimetry. Results obtained from the in vivo dosimetry of 20 patients are analyzed. Results obtained from forehead, abdomen, pelvis, and mediastinum showed a similar pattern with the average measured dose from 96 to 97% of the prescription dose. Extremities and chest received a dose greater than the prescription dose in many instances (more than 20% of measurements). Homogeneous dose delivery to the whole body is checked by calculating the mean dose with standard deviation for each fraction. Reasons for the difference between prescription dose and measured dose for each site are discussed. Dose homogeneity within ±10% is achieved using our in-house TBI protocol.

Patient dose analysis in total body irradiation through in vivo dosimetry

PubMed Central

Ganapathy, K.; Kurup, P. G. G.; Murali, V.; Muthukumaran, M.; Bhuvaneshwari, N.; Velmurugan, J.

2012-01-01

Total body irradiation (TBI) is a special radiotherapy technique, administered prior to bone marrow transplantation. Due to the complex nature of the treatment setup, in vivo dosimetry for TBI is mandatory to ensure proper delivery of the intended radiation dose throughout the body. Lithium fluoride (LiF) TLD-100 chips are used for the TBI in vivo dosimetry. Results obtained from the in vivo dosimetry of 20 patients are analyzed. Results obtained from forehead, abdomen, pelvis, and mediastinum showed a similar pattern with the average measured dose from 96 to 97% of the prescription dose. Extremities and chest received a dose greater than the prescription dose in many instances (more than 20% of measurements). Homogeneous dose delivery to the whole body is checked by calculating the mean dose with standard deviation for each fraction. Reasons for the difference between prescription dose and measured dose for each site are discussed. Dose homogeneity within ±10% is achieved using our in-house TBI protocol. PMID:23293453

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 03: Energy dependence of a clinical probe-format calorimeter and its pertinence to absolute photon and electron beam dosimetry

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

Renaud, James; Seuntjens, Jan; Sarfehnia, Arman

Purpose: To evaluate the intrinsic and absorbed-dose energy dependence of a small-scale graphite calorimeter probe (GPC) developed for use as a routine clinical dosimeter. The influence of charge deposition on the response of the GPC was also assessed by performing absolute dosimetry in clinical linac-based electron beams. Methods: Intrinsic energy dependence was determined by performing constant-temperature calorimetry dose measurements in a water-equivalent solid phantom, under otherwise reference conditions, in five high-energy photon (63.5 < %dd(10){sub X} < 76.3), and five electron (2.3 cm < R{sub 50} < 8.3 cm) beams. Reference dosimetry was performed for all beams in question usingmore » an Exradin A19 ion chamber with a calibration traceable to national standards. The absorbed-dose component of the overall energy dependence was calculated using the EGSnrc egs-chamber user code. Results: A total of 72 measurements were performed with the GPC, resulting in a standard error on the mean absorbed dose of better than 0.3 % for all ten beams. For both the photon and electron beams, no statistically-significant energy dependence was observed experimentally. Peak-to-peak, variations in the relative response of the GPC across all beam qualities of a given radiation type were on the order of 1 %. No effects, either transient or permanent, were attributable to the charge deposited by the electron beams. Conclusions: The GPC’s apparent energy-independence, combined with its well-established linearity and dose rate independence, make it a potentially useful dosimetry system capable measuring photon and electron doses in absolute terms at the clinical level.« less

FERRET-SAND II physics-dosimetry analysis for N Reactor Pressure Tubes 2954, 3053 and 1165 using a WIMS calculated input spectrum

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

McElroy, W.N.; Kellogg, L.S.; Matsumoto, W.Y.

1988-05-01

This report is in response to a request from Westinghouse Hanford Company (WHC) that the PNL National Dosimetry Center (NDC) perform physics-dosimetry analyses (E > MeV) for N Reactor Pressure Tubes 2954 and 3053. As a result of these analyses, and recommendations for additional studies, two physics-dosimetry re-evaluations for Pressure Tube 1165 were also accomplished. The primary objective of Pacific Northwest Laboratories' (PNL) National Dosimetry Center (NDC) physics-dosimetry work for N Reactor was to provide FERRET-SAND II physics-dosimetry results to assist in the assessment of neutron radiation-induced changes in the physical and mechanical properties of N Reactor pressure tubes. 15more » refs., 6 figs., 5 tabs.« less

Dosimetric characterization and output verification for conical brachytherapy surface applicators. Part I. Electronic brachytherapy source

PubMed Central

Fulkerson, Regina K.; Micka, John A.; DeWerd, Larry A.

2014-01-01

Purpose: Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR) 192Ir sources, as well as electronic brachytherapy sources. Part I of this paper will discuss the applicators used with electronic brachytherapy sources; Part II will discuss those used with HDR 192Ir sources. Although the use of these applicators has gained in popularity, the dosimetric characteristics including depth dose and surface dose distributions have not been independently verified. Additionally, there is no recognized method of output verification for quality assurance procedures with applicators like these. Existing dosimetry protocols available from the AAPM bookend the cross-over characteristics of a traditional brachytherapy source (as described by Task Group 43) being implemented as a low-energy superficial x-ray beam (as described by Task Group 61) as observed with the surface applicators of interest. Methods: This work aims to create a cohesive method of output verification that can be used to determine the dose at the treatment surface as part of a quality assurance/commissioning process for surface applicators used with HDR electronic brachytherapy sources (Part I) and 192Ir sources (Part II). Air-kerma rate measurements for the electronic brachytherapy sources were completed with an Attix Free-Air Chamber, as well as several models of small-volume ionization chambers to obtain an air-kerma rate at the treatment surface for each applicator. Correction factors were calculated using MCNP5 and EGSnrc Monte Carlo codes in order to determine an applicator-specific absorbed dose to water at the treatment surface from the measured air-kerma rate. Additionally, relative dose

SU-F-I-13: Correction Factor Computations for the NIST Ritz Free Air Chamber for Medium-Energy X Rays

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

Bergstrom, P

Purpose: The National Institute of Standards and Technology (NIST) uses 3 free-air chambers to establish primary standards for radiation dosimetry at x-ray energies. For medium-energy × rays, the Ritz free-air chamber is the main measurement device. In order to convert the charge or current collected by the chamber to the radiation quantities air kerma or air kerma rate, a number of correction factors specific to the chamber must be applied. Methods: We used the Monte Carlo codes EGSnrc and PENELOPE. Results: Among these correction factors are the diaphragm correction (which accounts for interactions of photons from the x-ray source inmore » the beam-defining diaphragm of the chamber), the scatter correction (which accounts for the effects of photons scattered out of the primary beam), the electron-loss correction (which accounts for electrons that only partially expend their energy in the collection region), the fluorescence correction (which accounts for ionization due to reabsorption ffluorescence photons and the bremsstrahlung correction (which accounts for the reabsorption of bremsstrahlung photons). We have computed monoenergetic corrections for the NIST Ritz chamber for the 1 cm, 3 cm and 7 cm collection plates. Conclusion: We find good agreement with other’s results for the 7 cm plate. The data used to obtain these correction factors will be used to establish air kerma and it’s uncertainty in the standard NIST x-ray beams.« less

Strengths and Weaknesses of a Planar Whole-Body Method of 153Sm Dosimetry for Patients with Metastatic Osteosarcoma and Comparison with Three-Dimensional Dosimetry

PubMed Central

Plyku, Donika; Loeb, David M.; Prideaux, Andrew R.; Baechler, Sébastien; Wahl, Richard L.; Sgouros, George

2015-01-01

Abstract Purpose: Dosimetric accuracy depends directly upon the accuracy of the activity measurements in tumors and organs. The authors present the methods and results of a retrospective tumor dosimetry analysis in 14 patients with a total of 28 tumors treated with high activities of 153Sm-ethylenediaminetetramethylenephosphonate (153Sm-EDTMP) for therapy of metastatic osteosarcoma using planar images and compare the results with three-dimensional dosimetry. Materials and Methods: Analysis of phantom data provided a complete set of parameters for dosimetric calculations, including buildup factor, attenuation coefficient, and camera dead-time compensation. The latter was obtained using a previously developed methodology that accounts for the relative motion of the camera and patient during whole-body (WB) imaging. Tumor activity values calculated from the anterior and posterior views of WB planar images of patients treated with 153Sm-EDTMP for pediatric osteosarcoma were compared with the geometric mean value. The mean activities were integrated over time and tumor-absorbed doses were calculated using the software package OLINDA/EXM. Results: The authors found that it was necessary to employ the dead-time correction algorithm to prevent measured tumor activity half-lives from often exceeding the physical decay half-life of 153Sm. Measured half-lives so long are unquestionably in error. Tumor-absorbed doses varied between 0.0022 and 0.27 cGy/MBq with an average of 0.065 cGy/MBq; however, a comparison with absorbed dose values derived from a three-dimensional analysis for the same tumors showed no correlation; moreover, the ratio of three-dimensional absorbed dose value to planar absorbed dose value was 2.19. From the anterior and posterior activity comparisons, the order of clinical uncertainty for activity and dose calculations from WB planar images, with the present methodology, is hypothesized to be about 70%. Conclusion: The dosimetric results from clinical

Calibration methodology application of kerma area product meters in situ: Preliminary results

NASA Astrophysics Data System (ADS)

Costa, N. A.; Potiens, M. P. A.

2014-11-01

The kerma-area product (KAP) is a useful quantity to establish the reference levels of conventional X-ray examinations. It can be obtained by measurements carried out with a KAP meter on a plane parallel transmission ionization chamber mounted on the X-ray system. A KAP meter can be calibrated in laboratory or in situ, where it is used. It is important to use one reference KAP meter in order to obtain reliable quantity of doses on the patient. The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. It was manufactured following the IEC 60580 recommendations, an international standard for KAP meters. This study had the aim to calibrate KAP meters using the PDC in situ. Previous studies and the quality control program of the PDC have shown that it has good function in characterization tests of dosimeters with ionization chamber and it also has low energy dependence. Three types of KAP meters were calibrated in four different diagnostic X-ray equipments. The voltages used in the two first calibrations were 50 kV, 70 kV, 100 kV and 120 kV. The other two used 50 kV, 70 kV and 90 kV. This was related to the equipments limitations. The field sizes used for the calibration were 10 cm, 20 cm and 30 cm. The calibrations were done in three different cities with the purpose to analyze the reproducibility of the PDC. The results gave the calibration coefficient for each KAP meter and showed that the PDC can be used as a reference instrument to calibrate clinical KAP meters.

Radiotherapy dosimetry using a commercial OSL system.

PubMed

Viamonte, A; da Rosa, L A R; Buckley, L A; Cherpak, A; Cygler, J E

2008-04-01

A commercial optically stimulated luminescence (OSL) system developed for radiation protection dosimetry by Landauer, Inc., the InLight microStar reader, was tested for dosimetry procedures in radiotherapy. The system uses carbon-doped aluminum oxide, Al2O3:C, as a radiation detector material. Using this OSL system, a percent depth dose curve for 60Co gamma radiation was measured in solid water. Field size and SSD dependences of the detector response were also evaluated. The dose response relationship was investigated between 25 and 400 cGy. The decay of the response with time following irradiation and the energy dependence of the Al2O3:C OSL detectors were also measured. The results obtained using OSL dosimeters show good agreement with ionization chamber and diode measurements carried out under the same conditions. Reproducibility studies show that the response of the OSL system to repeated exposures is 2.5% (1sd), indicating a real possibility of applying the Landauer OSL commercial system for radiotherapy dosimetric procedures.

Passive particle dosimetry. [silver halide crystal growth

NASA Technical Reports Server (NTRS)

Childs, C. B.

1977-01-01

Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

Germanium-doped optical fiber for real-time radiation dosimetry

NASA Astrophysics Data System (ADS)

Mizanur Rahman, A. K. M.; Zubair, H. T.; Begum, Mahfuza; Abdul-Rashid, H. A.; Yusoff, Z.; Ung, N. M.; Mat-Sharif, K. A.; Wan Abdullah, W. S.; Amouzad Mahdiraji, Ghafour; Amin, Y. M.; Maah, M. J.; Bradley, D. A.

2015-11-01

Over the past three decades growing demand for individualized in vivo dosimetry and subsequent dose verification has led to the pursuit of newer, novel and economically feasible materials for dosimeters. These materials are to facilitate features such as real-time sensing and fast readouts. In this paper, purposely composed SiO2:Ge optical fiber is presented as a suitable candidate for dosimetry. The optical fiber is meant to take advantage of the RL/OSL technique, providing both online remote monitoring of dose rate, and fast readouts for absorbed dose. A laboratory-assembled OSL reader has been used to acquire the RL/OSL response to LINAC irradiations (6 MV photons). The notable RL characteristics observed include constant level of luminescence for the same dose rate (providing better consistency compared to TLD-500), and linearity of response in the radiotherapy range (1 Gy/min to 6 Gy/min). The OSL curve was found to conform to an exponential decay characteristic (illumination with low LED source). The Ge doping resulted in an effective atomic number, Zeff, of 13.5 (within the bone equivalent range). The SiO2:Ge optical fiber sensor, with efficient coupling, can be a viable solution for in vivo dosimetry, besides a broad range of applications.

Review on the characteristics of radiation detectors for dosimetry and imaging

NASA Astrophysics Data System (ADS)

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-01

The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general

PREFACE: 7th International Conference on 3D Radiation Dosimetry (IC3DDose)

NASA Astrophysics Data System (ADS)

Thwaites, David; Baldock, Clive

2013-06-01

IC3DDose 2013, the 7th International Conference on 3D Radiation Dosimetry held in Sydney, Australia from 4-8 November 2012, grew out of the DosGel series, which began as DosGel99, the 1st International Workshop on Radiation Therapy Gel Dosimetry in Lexington, Kentucky. Since 1999 subsequent DoSGel conferences were held in Brisbane, Australia (2001), Ghent, Belgium (2004), Sherbrooke, Canada (2006) and Crete, Greece (2008). In 2010 the conference was held on Hilton Head Island, South Carolina and underwent a name-change to IC3DDose. The aim of the first workshop was to bring together individuals, both researchers and users, with an interest in 3D radiation dosimetry techniques, with a mix of presentations from basic science to clinical applications, which has remained an objective for all of the meetings. One rationale of DosGel99 was stated as supporting the increasing clinical implementation of gel dosimetry, as the technique appeared, at that time, to be leaving the laboratories of gel dosimetry enthusiasts and entering clinical practice. Clearly by labelling the first workshop as the 1st, there was a vision of a continuing series, which has been fulfilled. On the other hand, the expectation of widespread clinical use of gel dosimetry has perhaps not been what was hoped for and anticipated. Nevertheless the rapidly increasing demand for advanced high-precision 3D radiotherapy technology and techniques has continued apace. The need for practical and accurate 3D dosimetry methods for development and quality assurance has only increased. By the 6th meeting, held in South Carolina in 2010, the Conference Scientific Committee recognised the wider developments in 3D systems and methods and decided to widen the scope, whilst keeping the same span from basic science to applications. This was signalled by a change of name from 'Dosgel' to 'IC3DDose', a name that has continued to this latest conference. The conference objectives were: to enhance the quality and accuracy of

Assessment of the feasibility of using transrectal ultrasound for postimplant dosimetry in low-dose-rate prostate brachytherapy

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

Davies, Rhian Siân, E-mail: rhian.s.davies@wales.nhs.uk; Perrett, Teresa; Powell, Jane

A study was performed to establish whether transrectal ultrasound (TRUS)-based postimplant dosimetry (PID) is both practically feasible and comparable to computed tomography (CT)-based PID, recommended in current published guidelines. In total, 22 patients treated consecutively at a single cancer center with low-dose-rate (LDR) brachytherapy for early-stage prostate cancer had a transrectal ultrasound performed immediately after implant (d0-TRUS) and computed tomography scan 30 days after implant (d30-CT). Postimplant dosimetry planning was performed on both image sets and the results were compared. The interobserver reproducibility of the transrectal ultrasound postimplant dosimetry planning technique was also assessed. It was noticed that there wasmore » no significant difference in mean prostate D{sub 90} (136.5 Gy and 144.4 Gy, p = 0.2197), V{sub 100} (86.4% and 89.1%, p = 0.1480) and V{sub 150} (52.0% and 47.8%, p = 0.1657) for d30-CT and d0-TRUS, respectively. Rectal doses were significantly higher for d0-TRUS than d30-CT. Urethral doses were available with d0-TRUS only. We have shown that d0-TRUS PID is a useful tool for assessing the quality of an implant after low-dose-rate prostate brachytherapy and is comparable to d30-CT PID. There are clear advantages to its use in terms of resource and time efficiency both for the clinical team and the patient.« less

Evaluation of [18F]Mefway biodistribution and dosimetry based on whole-body PET imaging of mice.

PubMed

Constantinescu, Cristian C; Sevrioukov, Evgueni; Garcia, Adriana; Pan, Min-Liang; Mukherjee, Jogeshwar

2013-04-01

[(18)F]Mefway is a novel radiotracer specific to the serotonin 5-HT1A receptor class. In preparation for using this tracer in humans, we have performed whole-body PET studies in mice to evaluate the biodistribution and dosimetry of [(18)F]Mefway. Six mice (three females and three males) received IV injections of [(18)F]Mefway and were scanned for 2 h in an Inveon-dedicated PET scanner. Each animal also received a high-resolution CT scan using an Inveon CT. The CT images were used to draw volume of interest on the following organs: the brain, large intestine, stomach, heart, kidneys, liver, lungs, pancreas, bone, spleen, testes, thymus, gallbladder, uterus, and urinary bladder. All organ time-activity curves without decay correction were normalized to the injected activity. The area under the normalized curves was then used to compute the residence times in each organ. Data were analyzed using PMOD and Matlab software. The absorbed doses in mouse organs were computed using the RAdiation Dose Assessment Resource animal models for dose assessment. The residence times in mouse organs were converted to human values using scale factors based on differences between organ and body weights. OLINDA/EXM 1.1 software was used to compute the absorbed human doses in multiple organs for both female and male phantoms. The highest mouse residence times were found in the liver, urinary bladder, and kidneys. The largest doses in mice were found in the urinary bladder (critical organ), kidney, and liver for both females and males, indicating primary elimination via urinary system. The projected human effective doses were 1.21E - 02 mSv/MBq for the adult female model and 1.13E - 02 mSv/MBq for the adult male model. The estimated human biodistribution of [(18)F]Mefway was similar to that of [(11)C]WAY 100,635, a 5-HT1A tracer for which dosimetry has been evaluated in humans. The elimination of radiotracer was primarily via the kidney and urinary bladder with the urinary

Advanced radiochromic film methodologies for quantitative dosimetry of small and nonstandard fields

NASA Astrophysics Data System (ADS)

Rosen, Benjamin S.

Radiotherapy treatments with small and nonstandard fields are increasing in use as collimation and targeting become more advanced, which spare normal tissues while increasing tumor dose. However, dosimetry of small and nonstandard fields is more difficult than that of conventional fields due to loss of lateral charged-particle equilibrium, tight measurement setup requirements, source occlusion, and the volume-averaging effect of conventional dosimeters. This work aims to create new small and nonstandard field dosimetry protocols using radiochromic film (RCF) in conjunction with novel readout and analysis methodologies. It also is the intent of this work to develop an improved understanding of RCF structure and mechanics for its quantitative use in general applications. Conventional digitization techniques employ white-light, flatbed document scanners or scanning-laser densitometers which are not optimized for RCF dosimetry. A point-by-point precision laser densitometry system (LDS) was developed for this work to overcome the film-scanning artifacts associated with the use of conventional digitizers, such as positional scan dependence, off-axis light scatter, glass bed interference, and low signal-to-noise ratios. The LDS was shown to be optically traceable to national standards and to provide highly reproducible density measurements. Use of the LDS resulted in increased agreement between RCF dose measurements and the single-hit detector model of film response, facilitating traceable RCF calibrations based on calibrated physical quantities. GafchromicRTM EBT3 energy response to a variety of reference x-ray and gamma-ray beam qualities was also investigated. Conventional Monte Carlo methods are not capable of predicting film intrinsic energy response to arbitrary particle spectra. Therefore, a microdosimetric model was developed to simulate the underlying physics of the radiochromic mechanism and was shown to correctly predict the intrinsic response relative to a

Detour factors in water and plastic phantoms and their use for range and depth scaling in electron-beam dosimetry.