Sample records for gamma dosimetry

  1. 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.

  2. Gamma-ray dosimetry measurements of the Little Boy replica

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

    Plassmann, E.A.; Pederson, R.A.

    1984-01-01

    We present the current status of our gamma-ray dosimetry results for the Little Boy replica. Both Geiger-Mueller and thermoluminescent detectors were used in the measurements. Future work is needed to test assumptions made in data analysis.

  3. 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%.

  4. SU-F-P-15: Report On AAPM TG 178 Gamma Knife Dosimetry and Quality Assurance

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

    Goetsch, S

    Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocolmore » modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers Conclusion: The full TG 178 report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics. Consultant to Elekta, Inc.« less

  5. EPR dosimetry in a mixed neutron and gamma radiation field.

    PubMed

    Trompier, F; Fattibene, P; Tikunov, D; Bartolotta, A; Carosi, A; Doca, M C

    2004-01-01

    Suitability of Electron Paramagnetic Resonance (EPR) spectroscopy for criticality dosimetry was evaluated for tooth enamel, mannose and alanine pellets during the 'international intercomparison of criticality dosimetry techniques' at the SILENE reactor held in Valduc in June 2002, France. These three materials were irradiated in neutron and gamma-ray fields of various relative intensities and spectral distributions in order to evaluate their neutron sensitivity. The neutron response was found to be around 10% for tooth enamel, 45% for mannose and between 40 and 90% for alanine pellets according their type. According to the IAEA recommendations on the early estimate of criticality accident absorbed dose, analyzed results show the EPR potentiality and complementarity with regular criticality techniques.

  6. TH-A-BRC-02: AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance

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

    Goetsch, S.

    AAPM TG-135U1 QA for Robotic Radiosurgery - Sonja Dieterich Since the publication of AAPM TG-135 in 2011, the technology of robotic radiosurgery has rapidly developed. AAPM TG-135U1 will provide recommendations on the clinical practice for using the IRIS collimator, fiducial-less real-time motion tracking, and Monte Carlo based treatment planning. In addition, it will summarize currently available literature about uncertainties. Learning Objectives: Understand the progression of technology since the first TG publication Learn which new QA procedures should be implemented for new technologies Be familiar with updates to clinical practice guidelines AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance -more » Steven Goetsch Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers. Conclusion: The full report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and

  7. DSC studies on gamma irradiated poly(vinylidene fluoride) applied to high gamma dose dosimetry

    NASA Astrophysics Data System (ADS)

    Batista, Adriana S. M.; Faria, Luiz O.

    2017-11-01

    Poly(vinylidene fluoride) homopolymer (PVDF) was investigated for use on high gamma dose dosimetry. Samples were irradiated with gamma doses ranging from 100 kGy to 3000 kGy. Differential scanning calorimetry (DSC) was used to construct an unambiguous relationship between the melting transition latent heat (LM) and the absorbed dose (D). DSC thermograms were taken immediately, 1, 2 and 8 months after the irradiation process revealing that the LMx D relationship presented no change for doses ranging from 100 to 2750 kGy. FTIR and UV-Vis spectroscopy data revealed the radio-induction of C˭O and C˭C bonds. These radio-induced bonds were responsible by the chain stiffening and chain oxidation, respectively. SEM microscopy demonstrates that the spherulitic large crystalline structures present in pristine PVDF are destroyed with doses as low as 100 kGy. The DRX analysis revealed that the main effect of high gamma doses in the crystalline structure of PVDF is to provoke a change from the pristine PVDF α-phase to the γ-phase. Both the ability to detect gamma doses in a large dose range and the low fading features make PVDF homopolymers good candidates to be investigated as high gamma dose dosimeters.

  8. 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

  9. 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

  10. A round-robin gamma stereotactic radiosurgery dosimetry interinstitution comparison of calibration protocols

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

    Drzymala, R. E., E-mail: drzymala@wustl.edu; Alvarez, P. E.; Bednarz, G.

    2015-11-15

    Purpose: Absorbed dose calibration for gamma stereotactic radiosurgery is challenging due to the unique geometric conditions, dosimetry characteristics, and nonstandard field size of these devices. Members of the American Association of Physicists in Medicine (AAPM) Task Group 178 on Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance have participated in a round-robin exchange of calibrated measurement instrumentation and phantoms exploring two approved and two proposed calibration protocols or formalisms on ten gamma radiosurgery units. The objectives of this study were to benchmark and compare new formalisms to existing calibration methods, while maintaining traceability to U.S. primary dosimetry calibration laboratory standards. Methods:more » Nine institutions made measurements using ten gamma stereotactic radiosurgery units in three different 160 mm diameter spherical phantoms [acrylonitrile butadiene styrene (ABS) plastic, Solid Water, and liquid water] and in air using a positioning jig. Two calibrated miniature ionization chambers and one calibrated electrometer were circulated for all measurements. Reference dose-rates at the phantom center were determined using the well-established AAPM TG-21 or TG-51 dose calibration protocols and using two proposed dose calibration protocols/formalisms: an in-air protocol and a formalism proposed by the International Atomic Energy Agency (IAEA) working group for small and nonstandard radiation fields. Each institution’s results were normalized to the dose-rate determined at that institution using the TG-21 protocol in the ABS phantom. Results: Percentages of dose-rates within 1.5% of the reference dose-rate (TG-21 + ABS phantom) for the eight chamber-protocol-phantom combinations were the following: 88% for TG-21, 70% for TG-51, 93% for the new IAEA nonstandard-field formalism, and 65% for the new in-air protocol. Averages and standard deviations for dose-rates over all measurements relative to the TG

  11. Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry.

    PubMed

    Sohrabpour, M; Hassanzadeh, M; Shahriari, M; Sharifzadeh, M

    2002-10-01

    The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators.

  12. Technical Note: PRESAGE three-dimensional dosimetry accurately measures Gamma Knife output factors

    PubMed Central

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-01-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and two-dimensional detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ± 0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors. PMID:25368961

  13. 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.

  14. SU-F-T-294: The Analysis of Gamma Criteria for Delta4 Dosimetry Using Statistical Process Control

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

    Cho, S; Ahn, S; Kim, J

    Purpose: To evaluate the sensitivity of gamma criteria for patient-specific volumetric modulated arc therapy(VMAT) quality assurance of the Delta{sup 4} dosimetry program using the statistical process control(SPC) methodology. Methods: The authors selected 20 patient-specific VMAT QA cases which were undertaken MapCHECK and ArcCHECK with gamma pass rate better than 97%. The QAs data were collected Delta4 Phantom+ and Elekta Agility six megavolts without using an angle incrementer. The gamma index(GI) were calculated in 2D planes with normalizing deviation to local dose(local gamma). The sensitivity of the GI methodology using criterion of 3%/3mm, 3%/2mm and 2%/3mm was analyzed with using processmore » acceptability indices. We used local confidence(LC) level, the upper control limit(UCL) and lower control limit(LCL) of I-MR chart for process capability index(Cp) and a process acceptability index (Cpk). Results: The lower local confidence levels of 3%/3mm, 3%/2mm and 2%/3mm were 92.0%, 83.6% and 78.8% respectively. All of the calculated Cp and Cpk values that used LC level were under 1.0 in this study. The calculated LCLs of I-MR charts were 89.5%, 79.0% and 70.5% respectively. These values were higher than 1.0 which means good quality of QA. For the generally used lower limit of 90%, we acquired over 1.3 of Cp value for the gamma index of 3%/3mm and lower than 1.0 in the rest of GI. Conclusion: We applied SPC methodology to evaluate the sensitivity of gamma criteria and could see the lower control limits of VMAT QA for the Delta 4 dosimetry and could see that Delta 4 phantom+ dosimetry more affected by the position error and the I-MR chart derived values are more suitable for establishing lower limits. Acknowledgement: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (No. 2015R1D1A1A01060463)« less

  15. Neodymium oxide: A new thermoluminescent material for gamma dosimetry

    NASA Astrophysics Data System (ADS)

    Soliman, C.

    2006-10-01

    In the present study thermoluminescence (TL) glow curves of commercial and gamma (0.001 Gy to 100 kGy) exposed neodymium oxide (Nd 2O 3) have been investigated. The commercial glow curve is simple with TL peaks at 310, 350 and 385 °C. The TL sensitivity was enhanced to ˜4.7 times the original value when the investigated material was subject to pre-heating treatment at 800 °C for 1 h. The effect of storage time at room temperature has been monitored for different γ-doses. The combination of good γ-dose response and high stability of defects offer the possibility of applying the investigated material to γ-ray dosimetry in radiotherapy and experimental radiology range.

  16. Tissue-equivalent TL sheet dosimetry system for X- and gamma-ray dose mapping.

    PubMed

    Nariyama, N; Konnai, A; Ohnishi, S; Odano, N; Yamaji, A; Ozasa, N; Ishikawa, Y

    2006-01-01

    To measure dose distribution for X- and gamma rays simply and accurately, a tissue-equivalent thermoluminescent (TL) sheet-type dosemeter and reader system were developed. The TL sheet is composed of LiF:Mg,Cu,P and ETFE polymer, and the thickness is 0.2 mm. For the TL reading, a square heating plate, 20 cm on each side, was developed, and the temperature distribution was measured with an infrared thermal imaging camera. As a result, linearity within 2% and the homogeneity within 3% were confirmed. The TL signal emitted is detected using a CCD camera and displayed as a spatial dose distribution. Irradiation using synchrotron radiation between 10 and 100 keV and (60)Co gamma rays showed that the TL sheet dosimetry system was promising for radiation dose mapping for various purposes.

  17. Tumor dosimetry for I-131 trastuzumab therapy in a Her2+ NCI N87 xenograft mouse model using the Siemens SYMBIA E gamma camera with a pinhole collimator

    NASA Astrophysics Data System (ADS)

    Lee, Young Sub; Kim, Jin Su; Deuk Cho, Kyung; Kang, Joo Hyun; Moo Lim, Sang

    2015-07-01

    We performed imaging and therapy using I-131 trastuzumab and a pinhole collimator attached to a conventional gamma camera for human use in a mouse model. The conventional clinical gamma camera with a 2-mm radius-sized pinhole collimator was used for monitoring the animal model after administration of I-131 trastuzumab The highest and lowest radiation-received organs were osteogenic cells (0.349 mSv/MBq) and skin (0.137 mSv/MBq), respectively. The mean coefficients of variation (%CV) of the effective dose equivalent and effective dose were 0.091 and 0.093 mSv/MBq respectively. We showed the feasibility of the pinholeattached conventional gamma camera for human use for the assessment of dosimetry. Mouse dosimetry and prediction of human dosimetry could be used to provide data for the safety and efficacy of newly developed therapeutic schemes.

  18. On neutron-gamma mixed field dosimetry with LiF:Mg,Ti at radiation protection dose levels.

    PubMed

    Weinstein, M; German, U; Alfassi, Z B

    2006-01-01

    The possibility of using the specific responses of the high temperature Peaks 6 and 7 and Peaks 4 and 5 to different LET radiations was mentioned in the past mainly for very high doses. The applicability of the two regions method for thermal neutrons--gamma ray mixed field dosimetry was investigated by analysing the response of LiF:Mg,Ti dosemeters irradiated to different ratios of thermal neutrons and gamma rays at radiation protection dose levels encountered in routine work conditions, up to approximately 50 mSv. The Region of Interest method was used to define the areas of the Peaks 4 + 5 and 6 + 7. We found that a simple algorithm can be used to determine with good accuracy the separate contributions of neutron and gamma doses.

  19. SU-E-T-117: Analysis of the ArcCHECK Dosimetry Gamma Failure Using the 3DVH System

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

    Cho, S; Choi, W; Lee, H

    2015-06-15

    Purpose: To evaluate gamma analysis failure for the VMAT patient specific QA using ArcCHECK cylindrical phantom. The 3DVH system(Sun Nuclear, FL) was used to analyze the dose difference statistic between measured dose and treatment planning system calculated dose. Methods: Four case of gamma analysis failure were selected retrospectively. Our institution gamma analysis indexes were absolute dose, 3%/3mm and 90%pass rate in the ArcCHECK dosimetry. The collapsed cone convolution superposition (CCCS) dose calculation algorithm for VMAT was used. Dose delivery was performed with Elekta Agility. The A1SL(standard imaging, WI) and cavity plug were used for point dose measurement. Delivery QA plansmore » and images were used for 3DVH Reference data instead of patient plan and image. The measured data of ‘.txt’ file was used for comparison at diodes to acquire a global dose level. The,.acml’ file was used for AC-PDP and to calculated point dose. Results: The global dose of 3DVH was calculated as 1.10 Gy, 1.13, 1.01 and 0.2 Gy respectively. The global dose of 0.2 Gy case was induced by distance discrepancy. The TPS calculated point dose of was 2.33 Gy to 2.77 Gy and 3DVH calculated dose was 2.33 Gy to 2.68 Gy. The maximum dose differences were −2.83% and −3.1% for TPS vs. measured dose and TPS vs. 3DVH calculated respectively in the same case. The difference between measured and 3DVH was 0.1% in that case. The 3DVH gamma pass rate was 98% to 99.7%. Conclusion: We found the TPS calculation error by 3DVH calculation using ArcCHECK measured dose. It seemed that our CCCS algorithm RTP system over estimated at the central region and underestimated scattering at the peripheral diode detector point. The relative gamma analysis and point dose measurement would be recommended for VMAT DQA in the gamma failure case of ArcCHECK dosimetry.« less

  20. 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).

  1. 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.

  2. SU-G-BRB-15: Verifications of Absolute and Relative Dosimetry of a Novel Stereotactic Breast Device: GammaPodTM

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

    Becker, S; Mossahebi, S; Yi, B

    Purpose: A dedicated stereotactic breast radiotherapy device, GammaPod, was developed to treat early stage breast cancer. The first clinical unit was installed and commissioned at University of Maryland. We report our methodology of absolute dosimetry in multiple calibration conditions and dosimetric verifications of treatment plans produced by the system. Methods: GammaPod unit is comprised of a rotating hemi-spherical source carrier containing 36 Co-60 sources and a concentric tungsten collimator providing beams of 15 and 25 mm. Absolute dose calibration formalism was developed with modifications to AAPM protocols for unique geometry and different calibration medium (acrylic, polyethylene or liquid water). Breastmore » cup-size specific and collimator output factors were measured and verified with respect to Monte-Carlo simulations for single isocenter plans. Multiple isocenter plans were generated for various target size, location and cup-sizes in phantoms and 20 breast cancer patients images. Stereotactic mini-farmer chamber, OSL and TLD detectors as well as radio-chromic films were used for dosimetric measurements. Results: At the time of calibration (1/14/2016), absolute dose rate of the GammaPod was established to be 2.10 Gy/min in acrylic for 25 mm for sources installed in March 2011. Output factor for 15 mm collimator was measured to be 0.950. Absolute dose calibration was independently verified by IROC-Houston with a TLD/Institution ratio of 0.99. Cup size specific output measurements in liquid water for single isocenter were found to be within 3.0% of MC simulations. Point-dose measurements of multiple isocenter treatment plans were found to be within −1.0 ± 1.2 % of treatment planning system while 2-dimensional gamma analysis yielded a pass rate of 97.9 ± 2.2 % using gamma criteria of 3% and 2mm. Conclusion: The first GammaPod treatment unit for breast stereotactic radiotherapy was successfully installed, calibrated and commissioned for patient

  3. Gamma Knife surgery for arteriovenous malformations in the brain: integration of time-resolved contrast-enhanced magnetic resonance angiography into dosimetry planning. Technical note.

    PubMed

    Taschner, Christian A; Le Thuc, Vianney; Reyns, Nicolas; Gieseke, Juergen; Gauvrit, Jean-Yves; Pruvo, Jean-Pierre; Leclerc, Xavier

    2007-10-01

    The aim of this study was to develop an algorithm for the integration of time-resolved contrast-enhanced magnetic resonance (MR) angiography into dosimetry planning for Gamma Knife surgery (GKS) of arteriovenous malformations (AVMs) in the brain. Twelve patients harboring brain AVMs referred for GKS underwent intraarterial digital subtraction (DS) angiography and time-resolved MR angiography while wearing an externally applied cranial stereotactic frame. Time-resolved MR angiography was performed on a 1.5-tesla MR unit (Achieva, Philips Medical Systems) using contrast-enhanced 3D fast field echo sequencing with stochastic central k-space ordering. Postprocessing with interactive data language (Research Systems, Inc.) produced hybrid data sets containing dynamic angiographic information and the MR markers necessary for stereotactic transformation. Image files were sent to the Leksell GammaPlan system (Elekta) for dosimetry planning. Stereotactic transformation of the hybrid data sets containing the time-resolved MR angiography information with automatic detection of the MR markers was possible in all 12 cases. The stereotactic coordinates of vascular structures predefined from time-resolved MR angiography matched with DS angiography data in all cases. In 10 patients dosimetry planning could be performed based on time-resolved MR angiography data. In two patients, time-resolved MR angiography data alone were considered insufficient. The target volumes showed a notable shift of centers between modalities. Integration of time-resolved MR angiography data into the Leksell GammaPlan system for patients with brain AVMs is feasible. The proposed algorithm seems concise and sufficiently robust for clinical application. The quality of the time-resolved MR angiography sequencing needs further improvement.

  4. 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.

  5. 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

  6. SU-F-T-272: Patient Specific Quality Assurance of Prostate VMAT Plans with Portal Dosimetry

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

    Darko, J; Osei, E; University of Waterloo, Waterloo, ON

    Purpose: To evaluate the effectiveness of using the Portal Dosimetry (PD) method for patient specific quality assurance of prostate VMAT plans. Methods: As per institutional protocol all VMAT plans were measured using the Varian Portal Dosimetry (PD) method. A gamma evaluation criterion of 3%-3mm with a minimum area gamma pass rate (gamma <1) of 95% is used clinically for all plans. We retrospectively evaluated the portal dosimetry results for 170 prostate patients treated with VMAT technique. Three sets of criterions were adopted for re-evaluating the measurements; 3%-3mm, 2%-2mm and 1%-1mm. For all criterions two areas, Field+1cm and MLC-CIAO were analysed.Tomore » ascertain the effectiveness of the portal dosimetry technique in determining the delivery accuracy of prostate VMAT plans, 10 patients previously measured with portal dosimetry, were randomly selected and their measurements repeated using the ArcCHECK method. The same criterion used in the analysis of PD was used for the ArcCHECK measurements. Results: All patient plans reviewed met the institutional criteria for Area Gamma pass rate. Overall, the gamma pass rate (gamma <1) decreases for 3%-3mm, 2%-2mm and 1%-1mm criterion. For each criterion the pass rate was significantly reduced when the MLC-CIAO was used instead of FIELD+1cm. There was noticeable change in sensitivity for MLC-CIAO with 2%-2mm criteria and much more significant reduction at 1%-1mm. Comparable results were obtained for the ArcCHECK measurements. Although differences were observed between the clockwise verses the counter clockwise plans in both the PD and ArcCHECK measurements, this was not deemed to be statistically significant. Conclusion: This work demonstrates that Portal Dosimetry technique can be effectively used for quality assurance of VMAT plans. Results obtained show similar sensitivity compared to ArcCheck. To reveal certain delivery inaccuracies, the use of a combination of criterions may provide an effective way in

  7. 1983 international intercomparison of nuclear accident dosimetry systems at Oak Ridge National Laboratory

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

    Swaja, R.E.; Greene, R.T.; Sims, C.S.

    1985-04-01

    An international intercomparison of nuclear accident dosimetry systems was conducted during September 12-16, 1983, at Oak Ridge National Laboratory (ORNL) using the Health Physics Research Reactor operated in the pulse mode to simulate criticality accidents. This study marked the twentieth in a series of annual accident dosimetry intercomparisons conducted at ORNL. Participants from ten organizations attended this intercomparison and measured neutron and gamma doses at area monitoring stations and on phantoms for three different shield conditions. Results of this study indicate that foil activation techniques are the most popular and accurate method of determining accident-level neutron doses at area monitoringmore » stations. For personnel monitoring, foil activation, blood sodium activation, and thermoluminescent (TL) methods are all capable of providing accurate dose estimates in a variety of radiation fields. All participants in this study used TLD's to determine gamma doses with very good results on the average. Chemical dosemeters were also shown to be capable of yielding accurate estimates of total neutron plus gamma doses in a variety of radiation fields. While 83% of all neutron measurements satisfied regulatory standards relative to reference values, only 39% of all gamma results satisfied corresponding guidelines for gamma measurements. These results indicate that continued improvement in accident dosimetry evaluation and measurement techniques is needed.« less

  8. Characterization of α-spodumene to OSL dosimetry

    NASA Astrophysics Data System (ADS)

    d'Amorim, R. A. P. O.; de Vasconcelos, D. A. A.; de Barros, V. S. M.; Khoury, H. J.; Souza, S. O.

    2014-02-01

    The aim of this paper is to evaluate the optically stimulated luminescence (OSL) response of spodumene (LiAlSi2O6) silicate and its potential use for gamma radiation dosimetry. A natural Brazilian crystal of α-spodumene was used in this study. After the crystal grinding, pellets with the diameter of 6.0 mm were prepared using a mixture of α-spodumene and polytetrafluoroethylene (Teflon®) (1:2). To study the OSL response, the samples were irradiated with gamma radiation beam of Co-60 and the response was measured using an OSL Reader in two modes of operation: Continuous-wave and pulsed stimulation. The results of the integrated OSL curve of the pellets irradiated with the dose of 30 Gy showed that their response is reproducible within ±2%. The variation of the OSL response upon the dose exhibits a linear response in the range from 30 Gy to 10 kGy, with a correlation coefficient of 0.99. It is possible to conclude that the α-LiAlSi2O6/Teflon® has a great potential for OSL dosimetry of high gamma doses.

  9. Reactor Dosimetry State of the Art 2008

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    . Williams, A. P. Ribaric and T. Schnauber. Agile high-fidelity MCNP model development techniques for rapid mechanical design iteration / J. A. Kulesza.Extension of Raptor-M3G to r-8-z geometry for use in reactor dosimetry applications / M. A. Hunter, G. Longoni and S. L. Anderson. In vessel exposure distributions evaluated with MCNP5 for Atucha II / J. M. Longhino, H. Blaumann and G. Zamonsky. Atucha I nuclear power plant azimutal ex-vessel flux profile evaluation / J. M. Longhino ... [et al.]. UFTR thermal column characterization and redesign for maximized thermal flux / C. Polit and A. Haghighat. Activation counter using liquid light-guide for dosimetry of neutron burst / M. Hayashi ... [et al.]. Control rod reactivity curves for the annular core research reactor / K. R. DePriest ... [et al.]. Specification of irradiation conditions in VVER-440 surveillance positions / V. Kochkin ... [et al.]. Simulations of Mg-Ar ionisation and TE-TE ionisation chambers with MCNPX in a straightforward gamma and beta irradiation field / S. Nievaart ... [et al.]. The change of austenitic stainless steel elements content in the inner parts of VVER-440 reactor during operation / V. Smutný, J. Hep and P. Novosad. Fast neutron environmental spectrometry using disk activation / G. Lövestam ... [et al.]. Optimization of the neutron activation detector location scheme for VVER-lOOO ex-vessel dosimetry / V. N. Bukanov ... [et al.]. Irradiation conditions for surveillance specimens located into plane containers installed in the WWER-lOOO reactor of unit 2 of the South-Ukrainian NPP / O. V. Grytsenko. V. N. Bukanov and S. M. Pugach. Conformity between LRO mock-ups and VVERS NPP RPV neutron flux attenuation / S. Belousov. Kr. Ilieva and D. Kirilova. FLUOLE: a new relevant experiment for PWR pressure vessel surveillance / D. Beretz ... [et al.]. Transport of neutrons and photons through the iron and water layers / M. J. Kost'ál ... [et al.]. Condition evaluation of spent nuclear fuel assemblies

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. A virtual dosimetry audit - Towards transferability of gamma index analysis between clinical trial QA groups.

    PubMed

    Hussein, Mohammad; Clementel, Enrico; Eaton, David J; Greer, Peter B; Haworth, Annette; Ishikura, Satoshi; Kry, Stephen F; Lehmann, Joerg; Lye, Jessica; Monti, Angelo F; Nakamura, Mitsuhiro; Hurkmans, Coen; Clark, Catharine H

    2017-12-01

    Quality assurance (QA) for clinical trials is important. Lack of compliance can affect trial outcome. Clinical trial QA groups have different methods of dose distribution verification and analysis, all with the ultimate aim of ensuring trial compliance. The aim of this study was to gain a better understanding of different processes to inform future dosimetry audit reciprocity. Six clinical trial QA groups participated. Intensity modulated treatment plans were generated for three different cases. A range of 17 virtual 'measurements' were generated by introducing a variety of simulated perturbations (such as MLC position deviations, dose differences, gantry rotation errors, Gaussian noise) to three different treatment plan cases. Participants were blinded to the 'measured' data details. Each group analysed the datasets using their own gamma index (γ) technique and using standardised parameters for passing criteria, lower dose threshold, γ normalisation and global γ. For the same virtual 'measured' datasets, different results were observed using local techniques. For the standardised γ, differences in the percentage of points passing with γ < 1 were also found, however these differences were less pronounced than for each clinical trial QA group's analysis. These variations may be due to different software implementations of γ. This virtual dosimetry audit has been an informative step in understanding differences in the verification of measured dose distributions between different clinical trial QA groups. This work lays the foundations for audit reciprocity between groups, particularly with more clinical trials being open to international recruitment. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. 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.

  16. Detection of anatomical changes in lung cancer patients with 2D time-integrated, 2D time-resolved and 3D time-integrated portal dosimetry: a simulation study

    NASA Astrophysics Data System (ADS)

    Wolfs, Cecile J. A.; Brás, Mariana G.; Schyns, Lotte E. J. R.; Nijsten, Sebastiaan M. J. J. G.; van Elmpt, Wouter; Scheib, Stefan G.; Baltes, Christof; Podesta, Mark; Verhaegen, Frank

    2017-08-01

    The aim of this work is to assess the performance of 2D time-integrated (2D-TI), 2D time-resolved (2D-TR) and 3D time-integrated (3D-TI) portal dosimetry in detecting dose discrepancies between the planned and (simulated) delivered dose caused by simulated changes in the anatomy of lung cancer patients. For six lung cancer patients, tumor shift, tumor regression and pleural effusion are simulated by modifying their CT images. Based on the modified CT images, time-integrated (TI) and time-resolved (TR) portal dose images (PDIs) are simulated and 3D-TI doses are calculated. The modified and original PDIs and 3D doses are compared by a gamma analysis with various gamma criteria. Furthermore, the difference in the D 95% (ΔD 95%) of the GTV is calculated and used as a gold standard. The correlation between the gamma fail rate and the ΔD 95% is investigated, as well the sensitivity and specificity of all combinations of portal dosimetry method, gamma criteria and gamma fail rate threshold. On the individual patient level, there is a correlation between the gamma fail rate and the ΔD 95%, which cannot be found at the group level. The sensitivity and specificity analysis showed that there is not one combination of portal dosimetry method, gamma criteria and gamma fail rate threshold that can detect all simulated anatomical changes. This work shows that it will be more beneficial to relate portal dosimetry and DVH analysis on the patient level, rather than trying to quantify a relationship for a group of patients. With regards to optimizing sensitivity and specificity, different combinations of portal dosimetry method, gamma criteria and gamma fail rate should be used to optimally detect certain types of anatomical changes.

  17. Detection of anatomical changes in lung cancer patients with 2D time-integrated, 2D time-resolved and 3D time-integrated portal dosimetry: a simulation study.

    PubMed

    Wolfs, Cecile J A; Brás, Mariana G; Schyns, Lotte E J R; Nijsten, Sebastiaan M J J G; van Elmpt, Wouter; Scheib, Stefan G; Baltes, Christof; Podesta, Mark; Verhaegen, Frank

    2017-07-12

    The aim of this work is to assess the performance of 2D time-integrated (2D-TI), 2D time-resolved (2D-TR) and 3D time-integrated (3D-TI) portal dosimetry in detecting dose discrepancies between the planned and (simulated) delivered dose caused by simulated changes in the anatomy of lung cancer patients. For six lung cancer patients, tumor shift, tumor regression and pleural effusion are simulated by modifying their CT images. Based on the modified CT images, time-integrated (TI) and time-resolved (TR) portal dose images (PDIs) are simulated and 3D-TI doses are calculated. The modified and original PDIs and 3D doses are compared by a gamma analysis with various gamma criteria. Furthermore, the difference in the D 95% (ΔD 95% ) of the GTV is calculated and used as a gold standard. The correlation between the gamma fail rate and the ΔD 95% is investigated, as well the sensitivity and specificity of all combinations of portal dosimetry method, gamma criteria and gamma fail rate threshold. On the individual patient level, there is a correlation between the gamma fail rate and the ΔD 95% , which cannot be found at the group level. The sensitivity and specificity analysis showed that there is not one combination of portal dosimetry method, gamma criteria and gamma fail rate threshold that can detect all simulated anatomical changes. This work shows that it will be more beneficial to relate portal dosimetry and DVH analysis on the patient level, rather than trying to quantify a relationship for a group of patients. With regards to optimizing sensitivity and specificity, different combinations of portal dosimetry method, gamma criteria and gamma fail rate should be used to optimally detect certain types of anatomical changes.

  18. Estimation and correction of produced light from prompt gamma photons on luminescence imaging of water for proton therapy dosimetry

    NASA Astrophysics Data System (ADS)

    Yabe, Takuya; Komori, Masataka; Toshito, Toshiyuki; Yamaguchi, Mitsutaka; Kawachi, Naoki; Yamamoto, Seiichi

    2018-02-01

    Although the luminescence images of water during proton-beam irradiation using a cooled charge-coupled device camera showed almost the same ranges of proton beams as those measured by an ionization chamber, the depth profiles showed lower Bragg peak intensities than those measured by an ionization chamber. In addition, a broad optical baseline signal was observed in depths that exceed the depth of the Bragg peak. We hypothesize that this broad baseline signal originates from the interaction of proton-induced prompt gamma photons with water. These prompt gamma photons interact with water to form high-energy Compton electrons, which may cause luminescence or Cherenkov emission from depths exceeding the location of the Bragg peak. To clarify this idea, we measured the luminescence images of water during the irradiations of protons in water with minimized parallax errors, and also simulated the produced light by the interactions of prompt gamma photons with water. We corrected the measured depth profiles of the luminescence images by subtracting the simulated distributions of the produced light by the interactions of prompt gamma photons in water. Corrections were also conducted using the estimated depth profiles of the light of the prompt gamma photons, as obtained from the off-beam areas of the luminescence images of water. With these corrections, we successfully obtained depth profiles that have almost identical distributions as the simulated dose distributions for protons. The percentage relative height of the Bragg peak with corrections to that of the simulation data increased to 94% from 80% without correction. Also, the percentage relative offset heights of the deeper part of the Bragg peak with corrections decreased to 0.2%-0.4% from 4% without correction. These results indicate that the luminescence imaging of water has potential for the dose distribution measurements for proton therapy dosimetry.

  19. A multicentre 'end to end' dosimetry audit of motion management (4DCT-defined motion envelope) in radiotherapy.

    PubMed

    Palmer, Antony L; Nash, David; Kearton, John R; Jafari, Shakardokht M; Muscat, Sarah

    2017-12-01

    External dosimetry audit is valuable for the assurance of radiotherapy quality. However, motion management has not been rigorously audited, despite its complexity and importance for accuracy. We describe the first end-to-end dosimetry audit for non-SABR (stereotactic ablative body radiotherapy) lung treatments, measuring dose accumulation in a moving target, and assessing adequacy of target dose coverage. A respiratory motion lung-phantom with custom-designed insert was used. Dose was measured with radiochromic film, employing triple-channel dosimetry and uncertainty reduction. The host's 4DCT scan, outlining and planning techniques were used. Measurements with the phantom static and then moving at treatment delivery separated inherent treatment uncertainties from motion effects. Calculated and measured dose distributions were compared by isodose overlay, gamma analysis, and we introduce the concept of 'dose plane histograms' for clinically relevant interpretation of film dosimetry. 12 radiotherapy centres and 19 plans were audited: conformal, IMRT (intensity modulated radiotherapy) and VMAT (volumetric modulated radiotherapy). Excellent agreement between planned and static-phantom results were seen (mean gamma pass 98.7% at 3% 2 mm). Dose blurring was evident in the moving-phantom measurements (mean gamma pass 88.2% at 3% 2 mm). Planning techniques for motion management were adequate to deliver the intended moving-target dose coverage. A novel, clinically-relevant, end-to-end dosimetry audit of motion management strategies in radiotherapy is reported. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Evaluation of The Combined Effects of Hyperthermia, Cobalt-60 Gamma Rays and IUdR on Cultured Glioblastoma Spheroid Cells and Dosimetry Using TLD-100

    PubMed Central

    Neshasteh-Riz, Ali; Rahdani, Rozhin; Mostaar, Ahmad

    2014-01-01

    Objective In radiation treatment, the irradiation which is effective enough to control the tumors far exceeds normal-tissues tolerance. Thus to avoid such unfavourable outcomes, some methods sensitizing the tumor cells to radiation are used. Iododeoxyuridine (IUdR) is a halogenated thymidine analogue that known to be effective as a radiosensitizer in human cancer therapy. Improving the potential efficacy of radiation therapy after combining to hyperthermia depends on the magnitude of the differential sensitization of the hyperthermic effects or on the differential cytotoxicity of the radiation effects on the tumor cells. In this study, we evaluated the combined effects of IUdR, hyperthermia and gamma rays of 60Co on human glioblastoma spheroids culture. Materials and Methods In this experimental study,the cultured spheroids with 100µm diameter were treated by 1 µM IUdR, 43°C hyperthermia for an hour and 2 Gy gamma rays, respectively. The DNA damages induced in cells were compared using alkaline comet assay method, and dosimetry was then performed by TLD-100. Comet scores were calculated as mean ± standard error of mean (SEM) using one-way ANOVA. Results Comparison of DNA damages induced by IUdR and hyperthermia + gamma treatment showed 2.67- and 1.92-fold enhancement, respectively, as compared to the damages induced by radiation alone or radiation combined IUdR. Dosimetry results showed the accurate dose delivered to cells. Conclusion Analysis of the comet tail moments of spheroids showed that the radiation treatments combined with hyperthermia and IUdR caused significant radiosensitization when compared to related results of irradiation alone or of irradiation with IUdR. These results suggest a potential clinical advantage of combining radiation with hyperthermia and indicate effectiveness of hyperthermia treatment in inducing cytotoxicity of tumor cells. PMID:24611138

  1. Time-resolved versus time-integrated portal dosimetry: the role of an object’s position with respect to the isocenter in volumetric modulated arc therapy

    NASA Astrophysics Data System (ADS)

    Schyns, Lotte E. J. R.; Persoon, Lucas C. G. G.; Podesta, Mark; van Elmpt, Wouter J. C.; Verhaegen, Frank

    2016-05-01

    The aim of this work is to compare time-resolved (TR) and time-integrated (TI) portal dosimetry, focussing on the role of an object’s position with respect to the isocenter in volumetric modulated arc therapy (VMAT). Portal dose images (PDIs) are simulated and measured for different cases: a sphere (1), a bovine bone (2) and a patient geometry (3). For the simulated case (1) and the experimental case (2), several transformations are applied at different off-axis positions. In the patient case (3), three simple plans with different isocenters are created and pleural effusion is simulated in the patient. The PDIs before and after the sphere transformations, as well as the PDIs with and without simulated pleural effusion, are compared using a TI and TR gamma analysis. In addition, the performance of the TI and TR gamma analyses for the detection of real geometric changes in patients treated with clinical plans is investigated and a correlation analysis is performed between gamma fail rates and differences in dose volume histogram (DVH) metrics. The TI gamma analysis can show large differences in gamma fail rates for the same transformation at different off-axis positions (or for different plan isocenters). The TR gamma analysis, however, shows consistent gamma fail rates. For the detection of real geometric changes in patients treated with clinical plans, the TR gamma analysis has a higher sensitivity than the TI gamma analysis. However, the specificity for the TR gamma analysis is lower than for the TI gamma analysis. Both the TI and TR gamma fail rates show no correlation with changes in DVH metrics. This work shows that TR portal dosimetry is fundamentally superior to TI portal dosimetry, because it removes the strong dependence of the gamma fail rate on the off-axis position/plan isocenter. However, for 2D TR portal dosimetry, it is still difficult to interpret gamma fail rates in terms of changes in DVH metrics for patients treated with VMAT.

  2. Criticality accident dosimetry systems: an international intercomparison at the SILENE reactor in 2002.

    PubMed

    Médioni, R; Asselineau, B; Verrey, B; Trompier, F; Itié, C; Texier, C; Muller, H; Pelcot, G; Clairand, I; Jacquet, X; Pochat, J L

    2004-01-01

    In criticality accident dosimetry and more generally for high dose measurements, special techniques are used to measure separately the gamma ray and neutron components of the dose. To improve these techniques and to check their dosimetry systems (physical and/or biological), a total of 60 laboratories from 29 countries (America, Europe, Asia) participated in an international intercomparaison, which took place in France from 9 to 21 June 2002, at the SILENE reactor in Valduc and at a pure gamma source in Fontenay-aux-Roses. This intercomparison was jointly organised by the IRSN and the CEA with the help of the NEA/OCDE and was partly supported by the European Communities. This paper describes the aim of this intercomparison, the techniques used by the participants and the two radiation sources and their characteristics. The experimental arrangements of the dosemeters for the irradiations in free air or on phantoms are given. Then the dosimetric quantities measured and reported by the participants are summarised, analysed and compared with the reference values. The present paper concerns only the physical dosimetry and essentially experiments performed on the SILENE facility. The results obtained with the biological dosimetry are published in two other papers of this issue.

  3. 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.

  4. TL detectors for gamma ray dose measurements in criticality accidents.

    PubMed

    Miljanić, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezević, Zeljka

    2007-01-01

    Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Bosković Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed.

  5. 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

  6. Comparison of calculated beta- and gamma-ray doses after the Fukushima accident with data from single-grain luminescence retrospective dosimetry of quartz inclusions in a brick sample

    PubMed Central

    Endo, Satoru; Fujii, Keisuke; Kajimoto, Tsuyoshi; Tanaka, Kenichi; Stepanenko, Valeriy; Kolyzhenkov, Timofey; Petukhov, Aleksey; Akhmedova, Umukusum; Bogacheva, Viktoriia

    2018-01-01

    Abstract To estimate the beta- and gamma-ray doses in a brick sample taken from Odaka, Minami-Soma City, Fukushima Prefecture, Japan, a Monte Carlo calculation was performed with Particle and Heavy Ion Transport code System (PHITS) code. The calculated results were compared with data obtained by single-grain retrospective luminescence dosimetry of quartz inclusions in the brick sample. The calculated result agreed well with the measured data. The dose increase measured at the brick surface was explained by the beta-ray contribution, and the slight slope in the dose profile deeper in the brick was due to the gamma-ray contribution. The skin dose was estimated from the calculated result as 164 mGy over 3 years at the sampling site. PMID:29385528

  7. Comparison of calculated beta- and gamma-ray doses after the Fukushima accident with data from single-grain luminescence retrospective dosimetry of quartz inclusions in a brick sample.

    PubMed

    Endo, Satoru; Fujii, Keisuke; Kajimoto, Tsuyoshi; Tanaka, Kenichi; Stepanenko, Valeriy; Kolyzhenkov, Timofey; Petukhov, Aleksey; Akhmedova, Umukusum; Bogacheva, Viktoriia

    2018-05-01

    To estimate the beta- and gamma-ray doses in a brick sample taken from Odaka, Minami-Soma City, Fukushima Prefecture, Japan, a Monte Carlo calculation was performed with Particle and Heavy Ion Transport code System (PHITS) code. The calculated results were compared with data obtained by single-grain retrospective luminescence dosimetry of quartz inclusions in the brick sample. The calculated result agreed well with the measured data. The dose increase measured at the brick surface was explained by the beta-ray contribution, and the slight slope in the dose profile deeper in the brick was due to the gamma-ray contribution. The skin dose was estimated from the calculated result as 164 mGy over 3 years at the sampling site.

  8. Neutron and gamma-ray dose-rates from the Little Boy replica

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

    Plassmann, E.A.; Pederson, R.A.

    1984-01-01

    We report dose-rate information obtained at many locations in the near vicinity of, and at distances out to 0.64 km from, the Little Boy replica while it was operated as a critical assembly. The measurements were made with modified conventional dosimetry instruments that used an Anderson-Braun detector for neutrons and a Geiger-Mueller tube for gamma rays with suitable electronic modules to count particle-induced pulses. Thermoluminescent dosimetry methods provide corroborative data. Our analysis gives estimates of both neutron and gamma-ray relaxation lengths in air for comparison with earlier calculations. We also show the neutron-to-gamma-ray dose ratio as a function of distancemore » from the replica. Current experiments and further data analysis will refine these results. 7 references, 8 figures.« less

  9. MAGAT gel and EBT2 film‐based dosimetry for evaluating source plugging‐based treatment plan in Gamma Knife stereotactic radiosurgery

    PubMed Central

    Vivekanandhan, S.; Kale, S.S.; Rath, G.K.; Senthilkumaran, S.; Thulkar, S.; Subramani, V.; Laviraj, M.A.; Bisht, R.K.; Mahapatra, A.K.

    2012-01-01

    This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging. The polymer gel contained in a head‐sized glass container simulated all major aspects of the treatment process of Gamma Knife radiosurgery. The 3D dose distribution recorded in the gel dosimeter was read using a 1.5T MRI scanner. Scanning protocol was: CPMG pulse sequence with 8 equidistant echoes, TR=7 s, echo step=14 ms, pixel size=0.5 mm x 0.5 mm, and slice thickness of 2 mm. Using a calibration relationship between absorbed dose and spin‐spin relaxation rate (R2), we converted R2 images to dose images. Volumetric dose comparison between treatment planning system (TPS) and gel measurement was accomplished using an in‐house MATLAB‐based program. The isodose overlay of the measured and computed dose distribution on axial planes was in close agreement. Gamma index analysis of 3D data showed more than 94% voxel pass rate for different tolerance criteria of 3%/2 mm, 3%/1 mm and 2%/2 mm. Film dosimetry with GAFCHROMIC EBT 2 film was also performed to compare the results with the calculated TPS dose. Gamma index analysis of film measurement for the same tolerance criteria used for gel measurement evaluation showed more than 95% voxel pass rate. Verification of gamma plan calculated dose on account of shield is not part of acceptance testing of Leksell Gamma Knife (LGK). Through this study we accomplished a volumetric comparison of dose distributions measured with a polymer gel dosimeter and Leksell GammaPlan (LGP) calculations for plans using plugging. We propose gel dosimeter as a quality assurance (QA) tool for verification of plug‐based planning. PACS number: 87.53.Ly, 87.55.‐x, 87

  10. 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

  11. Dose mapping inside a gamma irradiator measured with doped silica fibre dosimetry and Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Moradi, F.; Khandaker, M. U.; Mahdiraji, G. A.; Ung, N. M.; Bradley, D. A.

    2017-11-01

    In recent years doped silica fibre thermoluminescent dosimeters (TLD) have been demonstrated to have considerable potential for irradiation applications, benefitting from the available sensitivity, spatial resolution and dynamic dose range, with primary focus being on the needs of medical dosimetry. Present study concerns the dose distribution inside a cylindrically shaped gamma-ray irradiator cavity, with irradiator facilities such as the familiar 60Co versions being popularly used in industrial applications. Quality assurance of the radiation dose distribution inside the irradiation cell of such a device is of central importance in respect of the delivered dose to the irradiated material. Silica fibre TLD dose-rates obtained within a Gammacell-220 irradiator cavity show the existence of non-negligible dose distribution heterogeneity, by up to 20% and 26% in the radial and axial directions respectively, Monte Carlo simulations and available literature providing some support for present findings. In practice, it is evident that there is need to consider making corrections to nominal dose-rates in order to avoid the potential for under-dosing.

  12. 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®.

  13. Nuclear Decay Data for the International Reactor Dosimetry Library for Fission and Fusion (IRDFF): Updated Evaluations of the Half-Lives and Gamma Ray Intensities

    NASA Astrophysics Data System (ADS)

    Chechev, Valery P.; Kuzmenko, Nikolay K.

    2016-02-01

    Updated evaluations of the half-lives and prominent gamma ray intensities have been presented for 20 radionuclides - dosimetry reaction residuals. The new values of these decay characteristics recommended for the IRDFF library were obtained using the approaches and methodology adopted by the working group of the Decay Data Evaluation Project (DDEP) cooperation. The experimental data published up to 2014 were taken into account in updated evaluations. The list of radionuclides includes 3H, 18F, 22Na, 24Na, 46Sc, 51Cr, 54Mn, 59Fe, 57Co, 60Co, 57Ni, 64Cu, 88Y, 132Te, 131I, 140Ba, 140La, 141Ce, 182Ta, 198Au.

  14. Computational model of gamma irradiation room at ININ

    NASA Astrophysics Data System (ADS)

    Rodríguez-Romo, Suemi; Patlan-Cardoso, Fernando; Ibáñez-Orozco, Oscar; Vergara Martínez, Francisco Javier

    2018-03-01

    In this paper, we present a model of the gamma irradiation room at the National Institute of Nuclear Research (ININ is its acronym in Spanish) in Mexico to improve the use of physics in dosimetry for human protection. We deal with air-filled ionization chambers and scientific computing made in house and framed in both the GEANT4 scheme and our analytical approach to characterize the irradiation room. This room is the only secondary dosimetry facility in Mexico. Our aim is to optimize its experimental designs, facilities, and industrial applications of physical radiation. The computational results provided by our model are supported by all the known experimental data regarding the performance of the ININ gamma irradiation room and allow us to predict the values of the main variables related to this fully enclosed space to within an acceptable margin of error.

  15. Neutron dosimetry of the Little Boy device

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

    Pederson, R.A.; Plassmann, E.A.

    1984-01-01

    Neutron dose rates at several angular locations and at distances out to 0.5 mile have been measured during critical operation of the Little Boy replica. We used modified remmetes and thermoluminescent dosimetry techniques for the measurements. The present status of our analysis is presented including estimates of the neutron-dose-relaxation length in air and the variation of the neutron-to-gamma-ray dose ratio with distance from the replica. These results are preliminary and are subject to detector calibration measurements.

  16. The response characteristics of tetrazolium violet solutions to gamma irradiation

    NASA Astrophysics Data System (ADS)

    Emi-Reynolds, G.; Kovács, András; Fletcher, J. J.

    2007-08-01

    The dosimetry characteristics of various solutions of tetrazolium violet, TV, (2,5-diphenyl-3-(1-naphthyl)-2H-tetrazolium chloride) to gamma irradiation are reported. The optical absorption spectra of these solutions show peaks between 400 and 600 nm with a shoulder at around 550 nm. The dose response of the optical absorbance values of aqueous and aqueous-alcoholic solutions containing different concentrations of TV was measured in the 250 Gy up to 75 kGy dose range. The formation of formazan product was observed due to radiolytic reduction in both solutions. Its formation was found more pronounced in N 2-saturated as well as in alkaline solutions. The results indicate that the 1 mM TV solution can be used for food irradiation and medical sterilization dosimetry at gamma irradiation facilities.

  17. Transit dosimetry in IMRT with an a-Si EPID in direct detection configuration

    NASA Astrophysics Data System (ADS)

    Sabet, Mahsheed; Rowshanfarzad, Pejman; Vial, Philip; Menk, Frederick W.; Greer, Peter B.

    2012-08-01

    In this study an amorphous silicon electronic portal imaging device (a-Si EPID) converted to direct detection configuration was investigated as a transit dosimeter for intensity modulated radiation therapy (IMRT). After calibration to dose and correction for a background offset signal, the EPID-measured absolute IMRT transit doses for 29 fields were compared to a MatriXX two-dimensional array of ionization chambers (as reference) using Gamma evaluation (3%, 3 mm). The MatriXX was first evaluated as reference for transit dosimetry. The accuracy of EPID measurements was also investigated by comparison of point dose measurements by an ionization chamber on the central axis with slab and anthropomorphic phantoms in a range of simple to complex fields. The uncertainty in ionization chamber measurements in IMRT fields was also investigated by its displacement from the central axis and comparison with the central axis measurements. Comparison of the absolute doses measured by the EPID and MatriXX with slab phantoms in IMRT fields showed that on average 96.4% and 97.5% of points had a Gamma index<1 in head and neck and prostate fields, respectively. For absolute dose comparisons with anthropomorphic phantoms, the values changed to an average of 93.6%, 93.7% and 94.4% of points with Gamma index<1 in head and neck, brain and prostate fields, respectively. Point doses measured by the EPID and ionization chamber were within 3% difference for all conditions. The deviations introduced in the response of the ionization chamber in IMRT fields were<1%. The direct EPID performance for transit dosimetry showed that it has the potential to perform accurate, efficient and comprehensive in vivo dosimetry for IMRT.

  18. 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.

  19. Fast protocol for radiochromic film dosimetry using a cloud computing web application.

    PubMed

    Calvo-Ortega, Juan-Francisco; Pozo, Miquel; Moragues, Sandra; Casals, Joan

    2017-07-01

    To investigate the feasibility of a fast protocol for radiochromic film dosimetry to verify intensity-modulated radiotherapy (IMRT) plans. EBT3 film dosimetry was conducted in this study using the triple-channel method implemented in the cloud computing application (Radiochromic.com). We described a fast protocol for radiochromic film dosimetry to obtain measurement results within 1h. Ten IMRT plans were delivered to evaluate the feasibility of the fast protocol. The dose distribution of the verification film was derived at 15, 30, 45min using the fast protocol and also at 24h after completing the irradiation. The four dose maps obtained per plan were compared using global and local gamma index (5%/3mm) with the calculated one by the treatment planning system. Gamma passing rates obtained for 15, 30 and 45min post-exposure were compared with those obtained after 24h. Small differences respect to the 24h protocol were found in the gamma passing rates obtained for films digitized at 15min (global: 99.6%±0.9% vs. 99.7%±0.5%; local: 96.3%±3.4% vs. 96.3%±3.8%), at 30min (global: 99.5%±0.9% vs. 99.7%±0.5%; local: 96.5%±3.2% vs. 96.3±3.8%) and at 45min (global: 99.2%±1.5% vs. 99.7%±0.5%; local: 96.1%±3.8% vs. 96.3±3.8%). The fast protocol permits dosimetric results within 1h when IMRT plans are verified, with similar results as those reported by the standard 24h protocol. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  20. Feasibility of using two-dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry.

    PubMed

    Chung, Heeteak; Li, Jonathan; Samant, Sanjiv

    2011-04-08

    Two-dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from -0.2% ~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry.

  1. 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

  2. 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

  3. SU-F-BRE-13: Replacing Pre-Treatment Phantom QA with 3D In-Vivo Portal Dosimetry for IMRT Breast Cancer

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

    Stroom, J; Vieira, S; Greco, C

    Purpose: Pre-treatment QA of individual treatment plans requires costly linac time and physics effort. Starting with IMRT breast treatments, we aim to replace pre-treatment QA with in-vivo portal dosimetry. Methods: Our IMRT breast cancer plans are routinely measured using the ArcCheck device (SunNuclear). 2D-Gamma analysis is performed with 3%/3mm criteria and the percentage of points with gamma<1 (nG1) is calculated within the 50% isodose surface. Following AAPM recommendations, plans with nG1<90% are approved; others need further inspection and might be rejected. For this study, we used invivo portal dosimetry (IPD) to measure the 3D back-projected dose of the first threemore » fractions for IMRT breast plans. Patient setup was online corrected before for all measured fractions. To reduce patient related uncertainties, the three IPD results were averaged and 3D-gamma analysis was applied with abovementioned criteria . For a subset of patients, phantom portal dosimetry (PPD) was also performed on a slab phantom. Results: Forty consecutive breast patients with plans that fitted the EPID were analysed. The average difference between planned and IPD dose in the reference point was −0.7+/−1.6% (1SD). Variation in nG1 between the 3 invivo fractions was about 6% (1SD). The average nG1 for IPD was 89+/−6%, worse than ArcCheck (95+/−3%). This can be explained by patient related factors such as changes in anatomy and/or model deficiencies due to e.g. inhomogeneities. For the 20 cases with PPD, mean nG1 was equal to ArcCheck values, which indicates that the two systems are equally accurate. These data therefore suggest that proper criteria for 3D invivo verification of breast treatments should be nG1>80% instead of nG1>90%, which, for our breast cases, would result in 5% (2/40) further inspections. Conclusion: First-fraction in-vivo portal dosimetry using new gamma-evaluation criteria will replace phantom measurements in our institution, saving resources and

  4. An assessment of a 3D EPID-based dosimetry system using conventional two- and three-dimensional detectors for VMAT.

    PubMed

    Stevens, S; Dvorak, P; Spevacek, V; Pilarova, K; Bray-Parry, M; Gesner, J; Richmond, A

    2018-01-01

    To provide a 3D dosimetric evaluation of a commercial portal dosimetry system using 2D/3D detectors under ideal conditions using VMAT. A 2D ion chamber array, radiochromic film and gel dosimeter were utilised to provide a dosimetric evaluation of transit phantom and pre-treatment 'fluence' EPID back-projected dose distributions for a standard VMAT plan. In-house 2D and 3D gamma methods compared pass statistics relative to each dosimeter and TPS dose distributions. Fluence mode and transit EPID dose distributions back-projected onto phantom geometry produced 2D gamma pass rates in excess of 97% relative to other tested detectors and exported TPS dose planes when a 3%, 3 mm global gamma criterion was applied. Use of a gel dosimeter within a glass vial allowed comparison of measured 3D dose distributions versus EPID 3D dose and TPS calculated distributions. 3D gamma comparisons between modalities at 3%, 3 mm gave pass rates in excess of 92%. Use of fluence mode was indicative of transit results under ideal conditions with slightly reduced dose definition. 3D EPID back projected dose distributions were validated against detectors in both 2D and 3D. Cross validation of transit dose delivered to a patient is limited due to reasons of practicality and the tests presented are recommended as a guideline for 3D EPID dosimetry commissioning; allowing direct comparison between detector, TPS, fluence and transit modes. The results indicate achievable gamma scores for a complex VMAT plan in a homogenous phantom geometry and contributes to growing experience of 3D EPID dosimetry. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  5. 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%.

  6. Fundamentals of Materials, Techniques, and Instrumentation for OSL and FNTD Dosimetry

    NASA Astrophysics Data System (ADS)

    Akselrod, M. S.

    2011-05-01

    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. Different aspects of OSL theory, materials optical and dosimetric properties, instrumentation, and data processing algorithms are described. The next technological breakthrough was done with Fluorescent Nuclear Track Detectors (FNTD) that have some important advantages in measuring fast neutron and high energy heavy charge particles that have become the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research.

  7. 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

  8. Feasibility of using two‐dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry

    PubMed Central

    Li, Jonathan; Samant, Sanjiv

    2011-01-01

    Two‐dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from ‐0.2%~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry. PACS number: 87.55.N‐

  9. 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.

  10. 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

  11. Methods and computer readable medium for improved radiotherapy dosimetry planning

    DOEpatents

    Wessol, Daniel E.; Frandsen, Michael W.; Wheeler, Floyd J.; Nigg, David W.

    2005-11-15

    Methods and computer readable media are disclosed for ultimately developing a dosimetry plan for a treatment volume irradiated during radiation therapy with a radiation source concentrated internally within a patient or incident from an external beam. The dosimetry plan is available in near "real-time" because of the novel geometric model construction of the treatment volume which in turn allows for rapid calculations to be performed for simulated movements of particles along particle tracks therethrough. The particles are exemplary representations of alpha, beta or gamma emissions emanating from an internal radiation source during various radiotherapies, such as brachytherapy or targeted radionuclide therapy, or they are exemplary representations of high-energy photons, electrons, protons or other ionizing particles incident on the treatment volume from an external source. In a preferred embodiment, a medical image of a treatment volume irradiated during radiotherapy having a plurality of pixels of information is obtained.

  12. Evaluation of 3D Gamma index calculation implemented in two commercial dosimetry systems

    NASA Astrophysics Data System (ADS)

    Xing, Aitang; Arumugam, Sankar; Deshpande, Shrikant; George, Armia; Vial, Philip; Holloway, Lois; Goozee, Gary

    2015-01-01

    3D Gamma index is one of the metrics which have been widely used for clinical routine patient specific quality assurance for IMRT, Tomotherapy and VMAT. The algorithms for calculating the 3D Gamma index using global and local methods implemented in two software tools: PTW- VeriSoft® as a part of OCTIVIUS 4D dosimeter systems and 3DVHTM from Sun Nuclear were assessed. The Gamma index calculated by the two systems was compared with manual calculated for one data set. The Gamma pass rate calculated by the two systems was compared using 3%/3mm, 2%/2mm, 3%/2mm and 2%/3mm for two additional data sets. The Gamma indexes calculated by the two systems were accurate, but Gamma pass rates calculated by the two software tools for same data set with the same dose threshold were different due to the different interpolation of raw dose data by the two systems and different implementation of Gamma index calculation and other modules in the two software tools. The mean difference was -1.3%±3.38 (1SD) with a maximum difference of 11.7%.

  13. Fundamentals of Materials, Techniques, and Instrumentation for OSL and FNTD Dosimetry

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

    Akselrod, M. S.

    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 Al{sub 2}O{sub 3}:C as a material of choice for many dosimetric applications. Different aspects of OSL theory, materials optical and dosimetric properties,more » instrumentation, and data processing algorithms are described. The next technological breakthrough was done with Fluorescent Nuclear Track Detectors (FNTD) that have some important advantages in measuring fast neutron and high energy heavy charge particles that have become the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research.« less

  14. Application of spectroscopic techniques in the radiation dosimetry of glasses: An update

    NASA Astrophysics Data System (ADS)

    Natarajan, V.

    2009-07-01

    The colorimetry and thermoluminescence properties of gamma irradiated glass were reported in as early as 1920. The utility of radio-photoluminescence (RPL) of silver activated metaphosphate glass for monitoring high doses of accidental and routine gamma radiation was reported in the 1960s. Since then considerable amount of research work has been carried out to study the thermoluminescence (TL), optical absorption (OA), electron paramagnetic resonance (EPR) and optically stimulated luminescence (OSL) of different commercially available glasses for high as well as low dose applications. A brief review of the progress made in the spectroscopic studies of glasses during the past few decades and the application of glasses for radiation dosimetry has been given in this paper.

  15. Thermoluminescence dosimetry features of DY and Cu doped SrF2 nanoparticles under gamma irradiation.

    PubMed

    Zahedifar, M; Sadeghi, E; Kashefi Biroon, M; Harooni, S; Almasifard, F

    2015-11-01

    Dy and Cu-doped SrF2 nanoparticles (NPs) were synthesized by using co-precipitation method and their possible application to solid state dosimetry were studied and compared to that of pure SrF2 NPs. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used for sample characterization. The highest thermoluminescence (TL) response of SrF2:Dy and SrF2:Cu NPs were found respectively at 0.5 and 0.7mol% of Dy and Cu impurities. Seven overlapping glow peaks at 384, 406, 421, 449, 569, 495, 508K and three component glow peaks at 381, 421 and 467K were identified respectively for SrF2:Dy and SrF2:Cu NPs employing Tm-Tstop and computerized glow curve deconvolution (CGCD) methods. The TL sensitivity of SrF2:Dy is approximately the same as that of LiF:Mg,Ti (TLD-100) cheeps. Linear dose response were observed for the SrF2:Dy and SrF2:Cu NPs up to the absorbed doses of 1kGy and 10kGy correspondingly. Regarding other dosimetry characteristics of the produced NPs such as fading, reproducibility and thermal treatment, Dy and Cu doped SrF2 NPs recommend for high dose TL dosimetry applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. 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

  17. 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

  18. Technical basis for nuclear accident dosimetry at the Oak Ridge National Laboratory

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

    Kerr, G.D.; Mei, G.T.

    The Oak Ridge National Laboratory (ORNL) Environmental, Safety, and Health Emergency Response Organization has the responsibility of providing analyses of personnel exposures to neutrons and gamma rays from a nuclear accident. This report presents the technical and philosophical basis for the dose assessment aspects of the nuclear accident dosimetry (NAD) system at ORNL. The issues addressed are regulatory guidelines, ORNL NAD system components and performance, and the interpretation of dosimetric information that would be gathered following a nuclear accident.

  19. 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.

  20. 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

  1. Experimental verification of bremsstrahlung production and dosimetry predictions for 15.5 MeV electrons

    NASA Astrophysics Data System (ADS)

    Sanford, T. W. L.; Beutler, D. E.; Halbleib, J. A.; Knott, D. P.

    1991-12-01

    The radiation produced by a 15.5-MeV monoenergetic electron beam incident on optimized and nonoptimized bremsstrahlung targets is characterized using the ITS Monte Carlo code and measurements with equilibrated and nonequilibrated TLD dosimetry. Comparisons between calculations and measurements verify the calculations and demonstrate that the code can be used to predict both bremsstrahlung production and TLD response for radiation fields that are characteristic of those produced by pulsed simulators of gamma rays. The comparisons provide independent confirmation of the validity of the TLD calibration for photon fields characteristic of gamma-ray simulators. The empirical Martin equation, which is often used to calculate radiation dose from optimized bremsstrahlung targets, is examined, and its range of validity is established.

  2. Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry.

    PubMed

    Begum, Mahfuza; Rahman, A K M Mizanur; Abdul-Rashid, H A; Yusoff, Z; Begum, Mahbuba; Mat-Sharif, K A; Amin, Y M; Bradley, D A

    2015-06-01

    Important thermoluminescence (TL) properties of five (5) different core sizes Ge-doped optical fibers have been studied to develop new TL material with better response. These are drawn from same preform applying different speed and tension during drawing phase to produce Ge-doped optical fibers with five (5) different core sizes. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge-doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (SEM) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in Secondary Standard Dosimetry Lab (SSDL) was used for irradiation covering dose range from 1Gy to 10Gy. The essential dosimetric parameters that have been studied are TL linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5cm length are annealed at temperature of 400°C for 1h period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1h at 400°C and subsequently 2h at 100°C to yield the highest sensitivity. TL responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Zeff) is found in the range (13.25-13.69) which is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. TL properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation

  3. 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

  4. 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.

  5. A comprehensive evaluation of the PRESAGE/optical-CT 3D dosimetry system

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

    Sakhalkar, H. S.; Adamovics, J.; Ibbott, G.

    2009-01-15

    This work presents extensive investigations to evaluate the robustness (intradosimeter consistency and temporal stability of response), reproducibility, precision, and accuracy of a relatively new 3D dosimetry system comprising a leuco-dye doped plastic 3D dosimeter (PRESAGE) and a commercial optical-CT scanner (OCTOPUS 5x scanner from MGS Research, Inc). Four identical PRESAGE 3D dosimeters were created such that they were compatible with the Radiologic Physics Center (RPC) head-and-neck (H and N) IMRT credentialing phantom. Each dosimeter was irradiated with a rotationally symmetric arrangement of nine identical small fields (1x3 cm{sup 2}) impinging on the flat circular face of the dosimeter. A repetitiousmore » sequence of three dose levels (4, 2.88, and 1.28 Gy) was delivered. The rotationally symmetric treatment resulted in a dose distribution with high spatial variation in axial planes but only gradual variation with depth along the long axis of the dosimeter. The significance of this treatment was that it facilitated accurate film dosimetry in the axial plane, for independent verification. Also, it enabled rigorous evaluation of robustness, reproducibility and accuracy of response, at the three dose levels. The OCTOPUS 5x commercial scanner was used for dose readout from the dosimeters at daily time intervals. The use of improved optics and acquisition technique yielded substantially improved noise characteristics (reduced to {approx}2%) than has been achieved previously. Intradosimeter uniformity of radiochromic response was evaluated by calculating a 3D gamma comparison between each dosimeter and axially rotated copies of the same dosimeter. This convenient technique exploits the rotational symmetry of the distribution. All points in the gamma comparison passed a 2% difference, 1 mm distance-to-agreement criteria indicating excellent intradosimeter uniformity even at low dose levels. Postirradiation, the dosimeters were all found to exhibit a slight

  6. TU-G-BRD-08: In-Vivo EPID Dosimetry: Quantifying the Detectability of Four Classes of Errors

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

    Ford, E; Phillips, M; Bojechko, C

    Purpose: EPID dosimetry is an emerging method for treatment verification and QA. Given that the in-vivo EPID technique is in clinical use at some centers, we investigate the sensitivity and specificity for detecting different classes of errors. We assess the impact of these errors using dose volume histogram endpoints. Though data exist for EPID dosimetry performed pre-treatment, this is the first study quantifying its effectiveness when used during patient treatment (in-vivo). Methods: We analyzed 17 patients; EPID images of the exit dose were acquired and used to reconstruct the planar dose at isocenter. This dose was compared to the TPSmore » dose using a 3%/3mm gamma criteria. To simulate errors, modifications were made to treatment plans using four possible classes of error: 1) patient misalignment, 2) changes in patient body habitus, 3) machine output changes and 4) MLC misalignments. Each error was applied with varying magnitudes. To assess the detectability of the error, the area under a ROC curve (AUC) was analyzed. The AUC was compared to changes in D99 of the PTV introduced by the simulated error. Results: For systematic changes in the MLC leaves, changes in the machine output and patient habitus, the AUC varied from 0.78–0.97 scaling with the magnitude of the error. The optimal gamma threshold as determined by the ROC curve varied between 84–92%. There was little diagnostic power in detecting random MLC leaf errors and patient shifts (AUC 0.52–0.74). Some errors with weak detectability had large changes in D99. Conclusion: These data demonstrate the ability of EPID-based in-vivo dosimetry in detecting variations in patient habitus and errors related to machine parameters such as systematic MLC misalignments and machine output changes. There was no correlation found between the detectability of the error using the gamma pass rate, ROC analysis and the impact on the dose volume histogram. Funded by grant R18HS022244 from AHRQ.« less

  7. 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.

  8. ESR response of phenol compounds for dosimetry of gamma photon beams

    NASA Astrophysics Data System (ADS)

    Marrale, M.; Longo, A.; Panzeca, S.; Gallo, S.; Principato, F.; Tomarchio, E.; Parlato, A.; Buttafava, A.; Dondi, D.; Zeffiro, A.

    2014-11-01

    In the present paper we investigate the features of IRGANOX® 1076 phenols as a material for electron spin resonance (ESR) dosimetry. We experimentally analyzed the ESR response of pellets of IRGANOX® 1076 phenols irradiated with 60Co photons. The best experimental parameters (modulation amplitude and microwave power) for dosimetric applications have been obtained. The dependence of ESR signal as function of γ dose is found to be linear in the dose range studied (12-60 Gy) and the lowest measurable dose is found to be of the order of 1 Gy. The signal after irradiation is very stable in the first thirty days. From the point of view of the tissue equivalence, these materials have mass energy absorption coefficient values comparable with those of soft tissue.

  9. Workshop report on atomic bomb dosimetry-residual radiation exposure: recent research and suggestions for future studies.

    PubMed

    Kerr, George D; Egbert, Stephen D; Al-Nabulsi, Isaf; Beck, Harold L; Cullings, Harry M; Endo, Satoru; Hoshi, Masaharu; Imanaka, Tetsuji; Kaul, Dean C; Maruyama, Satoshi; Reeves, Glen I; Ruehm, Werner; Sakaguchi, Aya; Simon, Steven L; Spriggs, Gregory D; Stram, Daniel O; Tonda, Tetsuji; Weiss, Joseph F; Weitz, Ronald L; Young, Robert W

    2013-08-01

    There is a need for accurate dosimetry for studies of health effects in the Japanese atomic bomb survivors because of the important role that these studies play in worldwide radiation protection standards. International experts have developed dosimetry systems, such as the Dosimetry System 2002 (DS02), which assess the initial radiation exposure to gamma rays and neutrons but only briefly consider the possibility of some minimal contribution to the total body dose by residual radiation exposure. In recognition of the need for an up-to-date review of the topic of residual radiation exposure in Hiroshima and Nagasaki, recently reported studies were reviewed at a technical session at the 57th Annual Meeting of the Health Physics Society in Sacramento, California, 22-26 July 2012. A one-day workshop was also held to provide time for detailed discussion of these newer studies and to evaluate their potential use in clarifying the residual radiation exposures to the atomic-bomb survivors at Hiroshima and Nagasaki. Suggestions for possible future studies are also included in this workshop report.

  10. Workshop Report on Atomic Bomb Dosimetry--Residual Radiation Exposure: Recent Research and Suggestions for Future Studies

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

    None

    2013-06-06

    There is a need for accurate dosimetry for studies of health effects in the Japanese atomic bomb survivors because of the important role that these studies play in worldwide radiation protection standards. International experts have developed dosimetry systems, such as the Dosimetry System 2002 (DS02), which assess the initial radiation exposure to gamma rays and neutrons but only briefly consider the possibility of some minimal contribution to the total body dose by residual radiation exposure. In recognition of the need for an up-to-date review of the topic of residual radiation exposure in Hiroshima and Nagasaki, recently reported studies were reviewedmore » at a technical session at the 57th Annual Meeting of the Health Physics Society in Sacramento, California, 22-26 July 2012. A one-day workshop was also held to provide time for detailed discussion of these newer studies and to evaluate their potential use in clarifying the residual radiation exposures to the atomic-bomb survivors at Hiroshima and Nagasaki. Suggestions for possible future studies are also included in this workshop report.« less

  11. 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.

  12. 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.

  13. Very sensitive α-Al2O3:C polycrystals for thermoluminescent dosimetry.

    PubMed

    Fontainha, Críssia Carem Paiva; Alves, Neriene; Ferraz, Wilmar Barbosa; de Faria, Luiz Oliveira

    2018-05-07

    New materials have been widely investigated for ionizing radiation dosimetry for medical procedures. Carbon-doped alumina (α-Al 2 O 3 :C) have been reported to be excellent thermoluminescent (TL) and optically stimulated luminescence (OSL) radiation dosimeters. In the present study, we have synthetized nano and micro-sized α-Al 2 O 3 :C polycrystals, doped with different percentages of carbon atoms aiming to compare their efficiency as TL dosimeters. The dosimetric characteristics for X ray and gamma fields were investigated. Samples doped with different amounts of carbon atoms were sintered under different atmosphere conditions, at temperatures ranging from 1300 °C to 1750 °C. Among the investigated samples, the micro-sized alumina doped with 0.01% of carbon and sintered at 1700 °C under reducing atmosphere, has presented a very high TL output. The main TL peak is centered at 250 °C and has a linear behavior with photon dose in the dose range of 0.02-to-5000 mGy, with correlation coefficient very close to one (0.99991). Samples produced by using nanosized alumina have shown much lower TL output when compared to the samples with microsized alumina. The micro-sized alumina obtained by the methodology used in this work is a suitable candidate to be explored for application in X and Gamma radiation dosimetry. Copyright © 2018. Published by Elsevier Ltd.

  14. Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Badiger, N. M.

    2014-11-01

    Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. The use of the dicentric assay for biological dosimetry for radiation accidents in Bulgaria.

    PubMed

    Hadjidekova, Valeria; Hristova, Rositsa; Ainsbury, Elizabeth A; Atanasova, Petya; Popova, Ljubomira; Staynova, Albena

    2010-02-01

    This paper details the construction of a 137Cs gamma calibration curve that has been established for dicentric assay and the testing and validation of the curve through biological dosimetry in three situations of suspected workplace overexposure that arose accidentally or through negligence or lack of appropriate safety measures. The three situations were: (1) suspected 137Cs contamination in a factory air supply; (2) suspected exposure to an industrial 192Ir source; and (3) accidental exposure of construction workers to radiation from a 60Co radiotherapy source in a hospital medical physics department. From a total of 24 potentially-exposed subjects, only one worker was found to have a statistically significant dose (0.16 Gy, 95% confidence intervals 0.02-0.43 Gy). In all other cases, the main function of the biological dosimetry was to reassure the subjects that any dose received was low.

  20. Evaluation and mitigation of potential errors in radiochromic film dosimetry due to film curvature at scanning.

    PubMed

    Palmer, Antony L; Bradley, David A; Nisbet, Andrew

    2015-03-08

    This work considers a previously overlooked uncertainty present in film dosimetry which results from moderate curvature of films during the scanning process. Small film samples are particularly susceptible to film curling which may be undetected or deemed insignificant. In this study, we consider test cases with controlled induced curvature of film and with film raised horizontally above the scanner plate. We also evaluate the difference in scans of a film irradiated with a typical brachytherapy dose distribution with the film naturally curved and with the film held flat on the scanner. Typical naturally occurring curvature of film at scanning, giving rise to a maximum height 1 to 2 mm above the scan plane, may introduce dose errors of 1% to 4%, and considerably reduce gamma evaluation passing rates when comparing film-measured doses with treatment planning system-calculated dose distributions, a common application of film dosimetry in radiotherapy. The use of a triple-channel dosimetry algorithm appeared to mitigate the error due to film curvature compared to conventional single-channel film dosimetry. The change in pixel value and calibrated reported dose with film curling or height above the scanner plate may be due to variations in illumination characteristics, optical disturbances, or a Callier-type effect. There is a clear requirement for physically flat films at scanning to avoid the introduction of a substantial error source in film dosimetry. Particularly for small film samples, a compression glass plate above the film is recommended to ensure flat-film scanning. This effect has been overlooked to date in the literature.

  1. 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.

  2. CALCULATION OF GAMMA SPECTRA IN A PLASTIC SCINTILLATOR FOR ENERGY CALIBRATIONAND DOSE COMPUTATION.

    PubMed

    Kim, Chankyu; Yoo, Hyunjun; Kim, Yewon; Moon, Myungkook; Kim, Jong Yul; Kang, Dong Uk; Lee, Daehee; Kim, Myung Soo; Cho, Minsik; Lee, Eunjoong; Cho, Gyuseong

    2016-09-01

    Plastic scintillation detectors have practical advantages in the field of dosimetry. Energy calibration of measured gamma spectra is important for dose computation, but it is not simple in the plastic scintillators because of their different characteristics and a finite resolution. In this study, the gamma spectra in a polystyrene scintillator were calculated for the energy calibration and dose computation. Based on the relationship between the energy resolution and estimated energy broadening effect in the calculated spectra, the gamma spectra were simply calculated without many iterations. The calculated spectra were in agreement with the calculation by an existing method and measurements. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Radiation effects on MOS devices - dosimetry, annealing, irradiation sequence, and sources

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    This paper reports on some investigations of dosimetry, annealing, irradiation sequences, and radioactive sources, involved in the determination of radiation effects on MOS devices. Results show that agreement in the experimental and theoretical surface to average doses support the use of thermo-luminescent dosimeters (manganese activated calcium fluoride) in specifying the surface dose delivered to thin gate insulators of MOS devices. Annealing measurements indicate the existence of at least two energy levels,,s or a activation energies, for recovery of soft oxide MOS devices after irradiation by electrons, protons, and gammas. Damage sensitivities of MOS devices were found to be independent of combinations and sequences of radiation type or energies. Comparison of various gamma sources indicated a small dependence of damage sensitivity on the Cobalt facility, but a more significant dependence in the case of the Cesium source. These results were attributed to differences in the spectral content of the several sources.

  4. Dosimetric property of mineral extracted from calamari and exposed to gamma rays

    NASA Astrophysics Data System (ADS)

    Cruz-Zaragoza, E.; Roman-Lopez, J.; Cruz, L. Pérez; Furetta, C.; Chiaravalle, E.; Mangiacotti, M.; Marchesani, G.

    2013-07-01

    Dosimetric property of polymineral fraction, quartz mainly, obtained from calamari was investigated. The commercial calamari samples from China and Sud Africa were collected in the markets of Italy. All polymineral debris were extracted and isolated from the whole body of calamari. The surface of the polymineral samples was analyzed by using the Scanning Electron Microscopy (SEM) and their chemical composition was determined using Energy Dispersive Spectroscopy (EDS). The polymineral was exposed to gamma rays (60Co) at different doses (0.5-80 Gy) to determine dosimetric property. Thermoluminescent (TL) glow curves showed two peaks centered at around 98-100 °C and 128-138 °C temperature range. The glow curves have been analyzed by using a deconvolution program. A linear dose response between 0.5 to 20 Gy was observed. The TL response of the samples as a function of the time storage, fading, presented a reduction of about 36-40 % at the end of 24 h. The reproducibility of the TL response after ten cycles of irradiation-readout showed an acceptable standard deviation in dosimetry. The polimineral fraction obtained from calamari shows an interesting dosimetric property and it may be useful for dosimetry in gamma radiation field.

  5. 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.

  6. Video-rate optical dosimetry and dynamic visualization of IMRT and VMAT treatment plans in water using Cherenkov radiation

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

    Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M.; Davis, Scott C.

    Purpose: A novel technique for optical dosimetry of dynamic intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 (TG-119) C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a water tank dopedmore » with the fluorophore quinine sulfate. The ICCD acquisition was gated to the Linac target trigger pulse to reduce background light artifacts, read out for a single radiation pulse, and binned to a resolution of 512 × 512 pixels. The resulting videos were analyzed temporally for various regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR), and summed to obtain an overall light intensity distribution, which was compared to the expected dose distribution from the TPS using a gamma-index analysis. Results: The chosen camera settings resulted in 23.5 frames per second dosimetry videos. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.9% and 96.2% agreement between the experimentally captured Cherenkov light distribution and expected TPS dose distribution based upon a 3%/3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans, respectively. Conclusions: The results from this initial study demonstrate the first documented use of Cherenkov radiation for video-rate optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real

  7. A methodology for dosimetry audit of rotational radiotherapy using a commercial detector array.

    PubMed

    Hussein, Mohammad; Tsang, Yatman; Thomas, Russell A S; Gouldstone, Clare; Maughan, David; Snaith, Julia A D; Bolton, Steven C; Nisbet, Andrew; Clark, Catharine H

    2013-07-01

    To develop a methodology for the use of a commercial detector array in dosimetry audits of rotational radiotherapy. The methodology was developed as part of the development of a national audit of rotational radiotherapy. Ten cancer centres were asked to create a rotational radiotherapy treatment plan for a three-dimensional treatment-planning-system (3DTPS) test and audited. Phantom measurements using a commercial 2D ionisation chamber (IC) array were compared with measurements using 0.125 cm(3) IC, Gafchromic film and alanine pellets in the same plane. Relative and absolute gamma index (γ) comparisons were made for Gafchromic film and 2D-Array planes, respectively. Comparisons between individual detectors within the 2D-Array against the corresponding IC and alanine measurement showed a statistically significant concordance correlation coefficient (both ρc>0.998, p<0.001) with mean difference of -1.1 ± 1.1% and -0.8 ± 1.1%, respectively, in a high dose PTV. In the γ comparison between the 2D-Array and film it was that the 2D-Array was more likely to fail planes where there was a dose discrepancy due to the absolute analysis performed. It has been found that using a commercial detector array for a dosimetry audit of rotational radiotherapy is suitable in place of standard systems of dosimetry. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Evaluation and mitigation of potential errors in radiochromic film dosimetry due to film curvature at scanning

    PubMed Central

    Bradley, David A.; Nisbet, Andrew

    2015-01-01

    This work considers a previously overlooked uncertainty present in film dosimetry which results from moderate curvature of films during the scanning process. Small film samples are particularly susceptible to film curling which may be undetected or deemed insignificant. In this study, we consider test cases with controlled induced curvature of film and with film raised horizontally above the scanner plate. We also evaluate the difference in scans of a film irradiated with a typical brachytherapy dose distribution with the film naturally curved and with the film held flat on the scanner. Typical naturally occurring curvature of film at scanning, giving rise to a maximum height 1 to 2 mm above the scan plane, may introduce dose errors of 1% to 4%, and considerably reduce gamma evaluation passing rates when comparing film‐measured doses with treatment planning system‐calculated dose distributions, a common application of film dosimetry in radiotherapy. The use of a triple‐channel dosimetry algorithm appeared to mitigate the error due to film curvature compared to conventional single‐channel film dosimetry. The change in pixel value and calibrated reported dose with film curling or height above the scanner plate may be due to variations in illumination characteristics, optical disturbances, or a Callier‐type effect. There is a clear requirement for physically flat films at scanning to avoid the introduction of a substantial error source in film dosimetry. Particularly for small film samples, a compression glass plate above the film is recommended to ensure flat‐film scanning. This effect has been overlooked to date in the literature. PACS numbers: 87.55.Qr, 87.56.bg, 87.55.km PMID:26103181

  9. Experimental evaluation of x-ray acoustic computed tomography for radiotherapy dosimetry applications.

    PubMed

    Hickling, Susannah; Lei, Hao; Hobson, Maritza; Léger, Pierre; Wang, Xueding; El Naqa, Issam

    2017-02-01

    The aim of this work was to experimentally demonstrate the feasibility of x-ray acoustic computed tomography (XACT) as a dosimetry tool in a clinical radiotherapy environment. The acoustic waves induced following a single pulse of linear accelerator irradiation in a water tank were detected with an immersion ultrasound transducer. By rotating the collimator and keeping the transducer stationary, acoustic signals at varying angles surrounding the field were detected and reconstructed to form an XACT image. Simulated XACT images were obtained using a previously developed simulation workflow. Profiles extracted from experimental and simulated XACT images were compared to profiles measured with an ion chamber. A variety of radiation field sizes and shapes were investigated. XACT images resembling the geometry of the delivered radiation field were obtained for fields ranging from simple squares to more complex shapes. When comparing profiles extracted from simulated and experimental XACT images of a 4 cm × 4 cm field, 97% of points were found to pass a 3%/3 mm gamma test. Agreement between simulated and experimental XACT images worsened when comparing fields with fine details. Profiles extracted from experimental XACT images were compared to profiles obtained through clinical ion chamber measurements, confirming that the intensity of XACT images is related to deposited radiation dose. Seventy-seven percent of the points in a profile extracted from an experimental XACT image of a 4 cm × 4 cm field passed a 7%/4 mm gamma test when compared to an ion chamber measured profile. In a complicated puzzle-piece shaped field, 86% of the points in an XACT extracted profile passed a 7%/4 mm gamma test. XACT images with intensity related to the spatial distribution of deposited dose in a water tank were formed for a variety of field sizes and shapes. XACT has the potential to be a useful tool for absolute, relative and in vivo dosimetry. © 2016 American Association of

  10. Dosimetry for Small Fields in Stereotactic Radiosurgery Using Gafchromic MD-V2-55 Film, TLD-100 and Alanine Dosimeters

    PubMed Central

    Massillon-JL, Guerda; Cueva-Prócel, Diego; Díaz-Aguirre, Porfirio; Rodríguez-Ponce, Miguel; Herrera-Martínez, Flor

    2013-01-01

    This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK) and a modified linear accelerator (linac) for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55), alanine and thermoluminescent (TLD-100) dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in 60Co gamma-ray and 6 MV x-ray reference (10×10 cm2) fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not appropriate in fields

  11. Exposure Dose Reconstruction from EPR Spectra of Tooth Enamel Exposed to the Combined Effect of X-rays and Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Kirillov, V. A.; Kuchuro, J. I.

    2014-09-01

    We have used EPR dosimetry on tooth enamel to show that the combined effect of x-rays with effective energy 34 keV and gamma radiation with average energy 1250 keV leads to a significant increase in the reconstructed absorbed dose compared with the applied dose from a gamma source or from an x-ray source or from both sources of electromagnetic radiation. In simulation experiments, we develop an approach to estimating the contribution of diagnostic x-rays to the exposure dose formed in the tooth enamel by the combined effect of x-rays and gamma radiation.

  12. Hard beta and gamma emissions of 124I. Impact on occupational dose in PET/CT.

    PubMed

    Kemerink, G J; Franssen, R; Visser, M G W; Urbach, C J A; Halders, S G E A; Frantzen, M J; Brans, B; Teule, G J J; Mottaghy, F M

    2011-01-01

    The hard beta and gamma radiation of 124I can cause high doses to PET/CT workers. In this study we tried to quantify this occupational exposure and to optimize radioprotection. Thin MCP-Ns thermoluminescent dosimeters suitable for measuring beta and gamma radiation were used for extremity dosimetry, active personal dosimeters for whole-body dosimetry. Extremity doses were determined during dispensing of 124I and oral administration of the activity to the patient, the body dose during all phases of the PET/CT procedure. In addition, dose rates of vials and syringes as used in clinical practice were measured. The procedure for dispensing 124I was optimized using newly developed shielding. Skin dose rates up to 100 mSv/min were measured when in contact with the manufacturer's vial containing 370 MBq of 124I. For an unshielded 5 ml syringe the positron skin dose was about seven times the gamma dose. Before optimization of the preparation of 124I, using an already reasonably safe technique, the highest mean skin dose caused by handling 370 MBq was 1.9 mSv (max. 4.4 mSv). After optimization the skin dose was below 0.2 mSv. The highly energetic positrons emitted by 124I can cause high skin doses if radioprotection is poor. Under optimized conditions occupational doses are acceptable. Education of workers is of paramount importance.

  13. 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

  14. Fast, high-resolution 3D dosimetry utilizing a novel optical-CT scanner incorporating tertiary telecentric collimation

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

    Sakhalkar, H. S.; Oldham, M.

    2008-01-15

    This study introduces a charge coupled device (CCD) area detector based optical-computed tomography (optical-CT) scanner for comprehensive verification of radiation dose distributions recorded in nonscattering radiochromic dosimeters. Defining characteristics include: (i) a very fast scanning time of {approx}5 min to acquire a complete three-dimensional (3D) dataset, (ii) improved image formation through the use of custom telecentric optics, which ensures accurate projection images and minimizes artifacts from scattered and stray-light sources, and (iii) high resolution (potentially 50 {mu}m) isotropic 3D dose readout. The performance of the CCD scanner for 3D dose readout was evaluated by comparison with independent 3D readout frommore » the single laser beam OCTOPUS-scanner for the same PRESAGE dosimeters. The OCTOPUS scanner was considered the 'gold standard' technique in light of prior studies demonstrating its accuracy. Additional comparisons were made against calculated dose distributions from the ECLIPSE treatment-planning system. Dose readout for the following treatments were investigated: (i) a single rectangular beam irradiation to investigate small field and very steep dose gradient dosimetry away from edge effects, (ii) a 2-field open beam parallel-opposed irradiation to investigate dosimetry along steep dose gradients, and (iii) a 7-field intensity modulated radiation therapy (IMRT) irradiation to investigate dosimetry for complex treatment delivery involving modulation of fluence and for dosimetry along moderate dose gradients. Dose profiles, dose-difference plots, and gamma maps were employed to evaluate quantitative estimates of agreement between independently measured and calculated dose distributions. Results indicated that dose readout from the CCD scanner was in agreement with independent gold-standard readout from the OCTOPUS-scanner as well as the calculated ECLIPSE dose distribution for all treatments, except in regions within a few

  15. 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

  16. Feasibility study on the verification of actual beam delivery in a treatment room using EPID transit dosimetry.

    PubMed

    Baek, Tae Seong; Chung, Eun Ji; Son, Jaeman; Yoon, Myonggeun

    2014-12-04

    The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam delivery based on detection of large errors in treatment room. Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from four lung cancer patients and used in the irradiation of an anthropomorphic phantom. The proposed method was evaluated by comparing the calculated dose map from TPS and EPID measurement on the same plane using a gamma index method with a 3% dose and 3 mm distance-to-dose agreement tolerance limit. In a simulation using a homogeneous plastic water phantom, performed to verify the effectiveness of the proposed method, the average passing rate of the transit dose based on gamma index was high enough, averaging 94.2% when there was no error during beam delivery. The passing rate of the transit dose for 24 IMRT fields was lower with the anthropomorphic phantom, averaging 86.8% ± 3.8%, a reduction partially due to the inaccuracy of TPS calculations for inhomogeneity. Compared with the TPS, the absolute value of the transit dose at the beam center differed by -0.38% ± 2.1%. The simulation study indicated that the passing rate of the gamma index was significantly reduced, to less than 40%, when a wrong field was erroneously irradiated to patient in the treatment room. This feasibility study suggested that transit dosimetry based on the calculation with commercial TPS and EPID measurement with simple calibration can provide information about large errors for treatment beam delivery.

  17. Dosimetric property of mineral extracted from calamari and exposed to gamma rays

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

    Cruz-Zaragoza, E.; Roman-Lopez, J.; Cruz, L. Perez

    2013-07-03

    Dosimetric property of polymineral fraction, quartz mainly, obtained from calamari was investigated. The commercial calamari samples from China and Sud Africa were collected in the markets of Italy. All polymineral debris were extracted and isolated from the whole body of calamari. The surface of the polymineral samples was analyzed by using the Scanning Electron Microscopy (SEM) and their chemical composition was determined using Energy Dispersive Spectroscopy (EDS). The polymineral was exposed to gamma rays ({sup 60}Co) at different doses (0.5-80 Gy) to determine dosimetric property. Thermoluminescent (TL) glow curves showed two peaks centered at around 98-100 Degree-Sign C and 128-138more » Degree-Sign C temperature range. The glow curves have been analyzed by using a deconvolution program. A linear dose response between 0.5 to 20 Gy was observed. The TL response of the samples as a function of the time storage, fading, presented a reduction of about 36-40 % at the end of 24 h. The reproducibility of the TL response after ten cycles of irradiation-readout showed an acceptable standard deviation in dosimetry. The polimineral fraction obtained from calamari shows an interesting dosimetric property and it may be useful for dosimetry in gamma radiation field.« less

  18. 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."

  19. Polybutadiene and Styrene-Butadiene rubbers for high-dose dosimetry

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

    Oliveira, Lucas N.; Instituto de Pesquisas Energeticas e Nucleares -IPEN, Sao Paulo-SP; Vieira, Silvio L.

    2015-07-01

    Polybutadiene and Styrene-Butadiene are synthetical rubbers used widely for pneumatic tires manufacturing. In this research, the dosimeter characteristics of those rubbers were studied for application in high-dose dosimetry. The rubber samples were irradiated with doses of 10 Gy up to 10 kGy, using a {sup 60}Co Gamma Cell-220 system (dose rate of 1.089 kGy/h) and their readings were taken on a Fourier Transform Infrared Spectroscopy-FTIR system (model Frontier/Perkin Elmer). The ratios of two absorbance peaks were taken for each kind of rubber spectrum, Polybutadiene (1306/1130 cm{sup -1}) and Styrene-Butadiene (1449/1306 cm{sup -1}). The ratio calculated was used as the responsemore » to the irradiation, and is not uniform across the sample. From the results, it can be concluded for both rubbers: a) the dose-response curves may be useful for high-dose dosimetry (greater than 250 Gy); b) their response for reproducibility presented standard deviations lower than 2.5%; c) the relative sensitivity was higher for Styrene-Butadiene (1.86 kGy{sup -1}) than for Polybutadiene (1.81 kGy{sup -1}), d) for doses of 10 kGy to 200 kGy, there was no variation in the dosimetric response. Both types of rubber samples showed usefulness as high-dose dosimeters. (authors)« less

  20. 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

  1. 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

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. Poster - 22: Retrospective analysis of portal dosimetry based QA of Prostate VMAT Plans

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

    Badu, Shyam; Darko, Johnson; Fleck, Andre

    2016-08-15

    Purpose: The purpose of this study is to retrospectively analyze the portal dosimetry based quality assurance of prostate VMAT plans. Methods: Our standard quality assurance of VMAT treatment plans are performed using EPID installed on Varian TrueBeam Linac. In our current study we analyzed 84 prostate pretreatment VMAT plans. All plans consisted of two arcs, 7800cGy in 39 fractions with a 6MV beam. For each of these VMAT plans, the measured fluence for each arc is compared with the reference fluence using gamma index analysis. Results: We have compared the gamma passing rates for three criteria; 3%/3mm, 2%/2mm and 1%/1mm.more » Out of 168 arcs measured, the number below the gamma passing rate 95% using the area, Field+1cm, are 0, 2, and 124 for 3%/3mm, 2%/2mm and 1%/1mm criteria respectively. Corresponding numbers for MLC CIAO are 0, 2, and 139 respectively. The average gamma passing rate for all arcs measured using Field+1cm are 99.9±0.4, 99.6±1.2, and 90.9±6.5 for 3%/3mm, 2%/2mm and 1%/1mm respectively. Similarly if the MLC CIAO area is analyzed, a passing rate of 99.9±0.2, 99.2±1.2 and 87.2±8.5 respectively was observed. The average of the maximum gamma was also found to increase with tighter criteria. Conclusion: Analysis of prostate VMAT quality assurance plans indicate that the gamma passing rate is sensitive to the criteria and the area analyzed.« less

  8. 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.

  9. 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.

  10. 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

  11. EPR TOOTH DOSIMETRY OF SNTS AREA INHABITANTS

    PubMed Central

    Sholom, Sergey; Desrosiers, Marc; Bouville, André; Luckyanov, Nicholas; Chumak, Vadim

    2009-01-01

    The determination of external dose to teeth of inhabitants of settlements near the Semipalatinsk Nuclear Test Site (SNTS) was conducted using the EPR dosimetry technique to assess radiation doses associated with exposure to radioactive fallout from the test site. In this study, tooth doses have been reconstructed for 103 persons with all studied teeth having been formed before the first nuclear test in 1949. Doses above those received from natural background radiation, termed “accident doses”, were found to lie in the range from zero to approximately 2 Gy, with one exception, a dose for one person from Semipalatinsk city was approximately 9 Gy. The variability of reconstructed doses within each of the settlements demonstrated heterogeneity of the deposited fallout as well as variations in lifestyle. The village mean external gamma doses for residents of nine[ settlements were in the range from a few tens of mGy to approximately 100 mGy. PMID:19590746

  12. EPR TOOTH DOSIMETRY OF SNTS AREA INHABITANTS.

    PubMed

    Sholom, Sergey; Desrosiers, Marc; Bouville, André; Luckyanov, Nicholas; Chumak, Vadim; Simon, Steven L

    2007-07-01

    The determination of external dose to teeth of inhabitants of settlements near the Semipalatinsk Nuclear Test Site (SNTS) was conducted using the EPR dosimetry technique to assess radiation doses associated with exposure to radioactive fallout from the test site. In this study, tooth doses have been reconstructed for 103 persons with all studied teeth having been formed before the first nuclear test in 1949. Doses above those received from natural background radiation, termed "accident doses", were found to lie in the range from zero to approximately 2 Gy, with one exception, a dose for one person from Semipalatinsk city was approximately 9 Gy. The variability of reconstructed doses within each of the settlements demonstrated heterogeneity of the deposited fallout as well as variations in lifestyle. The village mean external gamma doses for residents of nine[ settlements were in the range from a few tens of mGy to approximately 100 mGy.

  13. 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.

  14. 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

  15. Comparison of forward- and back-projection in vivo EPID dosimetry for VMAT treatment of the prostate

    NASA Astrophysics Data System (ADS)

    Bedford, James L.; Hanson, Ian M.; Hansen, Vibeke N.

    2018-01-01

    In the forward-projection method of portal dosimetry for volumetric modulated arc therapy (VMAT), the integrated signal at the electronic portal imaging device (EPID) is predicted at the time of treatment planning, against which the measured integrated image is compared. In the back-projection method, the measured signal at each gantry angle is back-projected through the patient CT scan to give a measure of total dose to the patient. This study aims to investigate the practical agreement between the two types of EPID dosimetry for prostate radiotherapy. The AutoBeam treatment planning system produced VMAT plans together with corresponding predicted portal images, and a total of 46 sets of gantry-resolved portal images were acquired in 13 patients using an iViewGT portal imager. For the forward-projection method, each acquisition of gantry-resolved images was combined into a single integrated image and compared with the predicted image. For the back-projection method, iViewDose was used to calculate the dose distribution in the patient for comparison with the planned dose. A gamma index for 3% and 3 mm was used for both methods. The results were investigated by delivering the same plans to a phantom and repeating some of the deliveries with deliberately introduced errors. The strongest agreement between forward- and back-projection methods is seen in the isocentric intensity/dose difference, with moderate agreement in the mean gamma. The strongest correlation is observed within a given patient, with less correlation between patients, the latter representing the accuracy of prediction of the two methods. The error study shows that each of the two methods has its own distinct sensitivity to errors, but that overall the response is similar. The forward- and back-projection EPID dosimetry methods show moderate agreement in this series of prostate VMAT patients, indicating that both methods can contribute to the verification of dose delivered to the patient.

  16. 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].

  17. Camel molar tooth enamel response to gamma rays using EPR spectroscopy.

    PubMed

    El-Faramawy, N A; El-Somany, I; Mansour, A; Maghraby, A M; Eissa, H; Wieser, A

    2018-03-01

    Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH pp ) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry.

  18. How gamma radiation processing systems are benefiting from the latest advances in information technology

    NASA Astrophysics Data System (ADS)

    Gibson, Wayne H.; Levesque, Daniel

    2000-03-01

    This paper discusses how gamma irradiation plants are putting the latest advances in computer and information technology to use for better process control, cost savings, and strategic advantages. Some irradiator operations are gaining significant benefits by integrating computer technology and robotics with real-time information processing, multi-user databases, and communication networks. The paper reports on several irradiation facilities that are making good use of client/server LANs, user-friendly graphics interfaces, supervisory control and data acquisition (SCADA) systems, distributed I/O with real-time sensor devices, trending analysis, real-time product tracking, dynamic product scheduling, and automated dosimetry reading. These plants are lowering costs by fast and reliable reconciliation of dosimetry data, easier validation to GMP requirements, optimizing production flow, and faster release of sterilized products to market. There is a trend in the manufacturing sector towards total automation using "predictive process control". Real-time verification of process parameters "on-the-run" allows control parameters to be adjusted appropriately, before the process strays out of limits. Applying this technology to the gamma radiation process, control will be based on monitoring the key parameters such as time, and making adjustments during the process to optimize quality and throughput. Dosimetry results will be used as a quality control measurement rather than as a final monitor for the release of the product. Results are correlated with the irradiation process data to quickly and confidently reconcile variations. Ultimately, a parametric process control system utilizing responsive control, feedback and verification will not only increase productivity and process efficiency, but can also result in operating within tighter dose control set points.

  19. 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 .

  20. Development of a calibration protocol for quantitative imaging for molecular radiotherapy dosimetry

    NASA Astrophysics Data System (ADS)

    Wevrett, J.; Fenwick, A.; Scuffham, J.; Nisbet, A.

    2017-11-01

    Within the field of molecular radiotherapy, there is a significant need for standardisation in dosimetry, in both quantitative imaging and dosimetry calculations. Currently, there are a wide range of techniques used by different clinical centres and as a result there is no means to compare patient doses between centres. To help address this need, a 3 year project was funded by the European Metrology Research Programme, and a number of clinical centres were involved in the project. One of the required outcomes of the project was to develop a calibration protocol for three dimensional quantitative imaging of volumes of interest. Two radionuclides were selected as being of particular interest: iodine-131 (131I, used to treat thyroid disorders) and lutetium-177 (177Lu, used to treat neuroendocrine tumours). A small volume of activity within a scatter medium (water), representing a lesion within a patient body, was chosen as the calibration method. To ensure ease of use in clinical centres, an "off-the-shelf" solution was proposed - to avoid the need for in-house manufacturing. The BIODEX elliptical Jaszczak phantom and 16 ml fillable sphere were selected. The protocol was developed for use on SPECT/CT gamma cameras only, where the CT dataset would be used to correct the imaging data for attenuation of the emitted photons within the phantom. The protocol corrects for scatter of emitted photons using the triple energy window correction technique utilised by most clinical systems. A number of clinical systems were tested in the development of this protocol, covering the major manufacturers of gamma camera generally used in Europe. Initial imaging was performed with 131I and 177Lu at a number of clinical centres, but due to time constraints in the project, some acquisitions were performed with 177Lu only. The protocol is relatively simplistic, and does not account for the effects of dead-time in high activity patients, the presence of background activity surrounding

  1. Sci—Thur AM: YIS - 03: irtGPUMCD: a new GPU-calculated dosimetry code for {sup 177}Lu-octreotate radionuclide therapy of neuroendocrine tumors

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

    Montégiani, Jean-François; Gaudin, Émilie; Després, Philippe

    2014-08-15

    In peptide receptor radionuclide therapy (PRRT), huge inter-patient variability in absorbed radiation doses per administered activity mandates the utilization of individualized dosimetry to evaluate therapeutic efficacy and toxicity. We created a reliable GPU-calculated dosimetry code (irtGPUMCD) and assessed {sup 177}Lu-octreotate renal dosimetry in eight patients (4 cycles of approximately 7.4 GBq). irtGPUMCD was derived from a brachytherapy dosimetry code (bGPUMCD), which was adapted to {sup 177}Lu PRRT dosimetry. Serial quantitative single-photon emission computed tomography (SPECT) images were obtained from three SPECT/CT acquisitions performed at 4, 24 and 72 hours after {sup 177}Lu-octreotate administration, and registered with non-rigid deformation of CTmore » volumes, to obtain {sup 177}Lu-octreotate 4D quantitative biodistribution. Local energy deposition from the β disintegrations was assumed. Using Monte Carlo gamma photon transportation, irtGPUMCD computed dose rate at each time point. Average kidney absorbed dose was obtained from 1-cm{sup 3} VOI dose rate samples on each cortex, subjected to a biexponential curve fit. Integration of the latter time-dose rate curve yielded the renal absorbed dose. The mean renal dose per administered activity was 0.48 ± 0.13 Gy/GBq (range: 0.30–0.71 Gy/GBq). Comparison to another PRRT dosimetry code (VRAK: Voxelized Registration and Kinetics) showed fair accordance with irtGPUMCD (11.4 ± 6.8 %, range: 3.3–26.2%). These results suggest the possibility to use the irtGPUMCD code in order to personalize administered activity in PRRT. This could allow improving clinical outcomes by maximizing per-cycle tumor doses, without exceeding the tolerable renal dose.« less

  2. 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

  3. 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.

  4. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    PubMed

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  5. 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".

  6. Analytical functions for beta and gamma absorbed fractions of iodine-131 in spherical and ellipsoidal volumes.

    PubMed

    Mowlavi, Ali Asghar; Fornasier, Maria Rossa; Mirzaei, Mohammd; Bregant, Paola; de Denaro, Mario

    2014-10-01

    The beta and gamma absorbed fractions in organs and tissues are the important key factors of radionuclide internal dosimetry based on Medical Internal Radiation Dose (MIRD) approach. The aim of this study is to find suitable analytical functions for beta and gamma absorbed fractions in spherical and ellipsoidal volumes with a uniform distribution of iodine-131 radionuclide. MCNPX code has been used to calculate the energy absorption from beta and gamma rays of iodine-131 uniformly distributed inside different ellipsoids and spheres, and then the absorbed fractions have been evaluated. We have found the fit parameters of a suitable analytical function for the beta absorbed fraction, depending on a generalized radius for ellipsoid based on the radius of sphere, and a linear fit function for the gamma absorbed fraction. The analytical functions that we obtained from fitting process in Monte Carlo data can be used for obtaining the absorbed fractions of iodine-131 beta and gamma rays for any volume of the thyroid lobe. Moreover, our results for the spheres are in good agreement with the results of MIRD and other scientific literatures.

  7. SU-E-J-70: Evaluation of Multiple Isocentric Intensity Modulated and Volumetric Modulated Arc Therapy Techniques Using Portal Dosimetry

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

    Muralidhar, K Raja; Pangam, S; Kolla, J

    2015-06-15

    Purpose: To develop a method for verification of dose distribution in a patient during treatment using multiple isocentric Intensity modulated and volumetric modulated arc therapy techniques with portal dosimetry. Methods: Varian True Beam accelerator, equipped with an aS1000 megavoltage electronic portal imaging device (EPID) has an integrated image mode for portal dosimetry (PD). The source-to-imager distance was taken at 150 cm to avoid collision to the table. Fourteen fractions were analyzed for this study. During shift in a single plan from one isocenter to another isocenter, EPID also shifted longitudinally for each field by taking the extent of divergence ofmore » beam into the consideration for EPID distance of 150cm. Patients were given treatment everyday with EPID placed in proper position for each field. Several parameters were obtained by comparing the dose distribution between fractions to fraction. The impact of the intra-fraction and inter-fraction of the patient in combination with isocenter shift of the beams were observed. Results: During treatment, measurements were performed by EPID and were evaluated by the gamma method. Analysis was done between fractions for multiple isocenter treatments. The pass rates of the gamma analysis with a criterion of 3% and 3 mm for the 14 fractions were over 97.8% with good consistency. Whereas maximum gamma exceeded the criteria in few fractions (in<1 cc vol). Average gamma was observed in the criteria of 0.5%. Maximum dose difference and average dose differences were less than 0.22 CU and 0.01 CU for maximum tolerance of 1.0 CU and 0.2 CU respectively. Conclusion: EPID with extended distance is ideal method to verify the multiple isocentric dose distribution in patient during treatment, especially cold and hot spots in junction dose. Verification of shifts as well as the dose differences between each fraction due to inter-fraction and intra-fraction of the patient can be derived.« less

  8. γTools: A modular multifunction phantom for quality assurance in GammaKnife treatments.

    PubMed

    Calusi, Silvia; Noferini, Linhsia; Marrazzo, Livia; Casati, Marta; Arilli, Chiara; Compagnucci, Antonella; Talamonti, Cinzia; Scoccianti, Silvia; Greto, Daniela; Bordi, Lorenzo; Livi, Lorenzo; Pallotta, Stefania

    2017-11-01

    We present the γTools, a new phantom designed to assess geometric and dosimetric accuracy in Gamma Knife treatments, together with first tests and results of applications. The phantom is composed of two modules: the imaging module, a regular grid of 1660 control points to evaluate image distortions and image registration result and the dosimetry module for delivered dose distribution measurements. The phantom is accompanied by a MatLab routine for image distortions quantification. Dose measurement are performed with Gafchromic films fixed between two inserts and placed in various positions and orientations inside the dosimetry module thus covering a volume comparable to the full volume of a head. Tests performed to assess the accuracy and precision of the imaging module demonstrated sub-millimetric values. As an example of possible applications, the phantom was employed to measure image distortions of two MRI scanners and to perform dosimetric studies of single shots delivered to homogeneous and heterogeneous materials. Due to the phantom material, the measured absolute dose do not correspond to the planned dose; doses comparisons are thus carried out between normalized dose distributions. Finally, an end-to-end test was carried out in the treatment of a neuroma-like target which resulted in a 100% gamma passing rate (2% local, 2 mm) and a distance between the real target perimeter and the prescription isodose centroids of about 1 mm. The tests demonstrate that the proposed phantom is suitable to assess both the geometrical and relative dosimetric accuracy of Gamma Knife radiosurgery treatments. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  9. 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

  10. Development of a digital method for neutron/gamma-ray discrimination based on matched filtering

    NASA Astrophysics Data System (ADS)

    Korolczuk, S.; Linczuk, M.; Romaniuk, R.; Zychor, I.

    2016-09-01

    Neutron/gamma-ray discrimination is crucial for measurements with detectors sensitive to both neutron and gamma-ray radiation. Different techniques to discriminate between neutrons and gamma-rays based on pulse shape analysis are widely used in many applications, e.g., homeland security, radiation dosimetry, environmental monitoring, fusion experiments, nuclear spectroscopy. A common requirement is to improve a radiation detection level with a high detection reliability. Modern electronic components, such as high speed analog to digital converters and powerful programmable digital circuits for signal processing, allow us to develop a fully digital measurement system. With this solution it is possible to optimize digital signal processing algorithms without changing any electronic components in an acquisition signal path. We report on results obtained with a digital acquisition system DNG@NCBJ designed at the National Centre for Nuclear Research. A 2'' × 2'' EJ309 liquid scintillator was used to register mixed neutron and gamma-ray radiation from PuBe sources. A dedicated algorithm for pulse shape discrimination, based on real-time filtering, was developed and implemented in hardware.

  11. 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

  12. An application of artificial neural intelligence for personal dose assessment using a multi-area OSL dosimetry system.

    PubMed

    Lee, S Y; Kim, B H; Lee, K J

    2001-06-01

    Significant advances have been made in recent years to improve measurement technology and performance of phosphor materials in the fields of optically stimulated luminescence (OSL) dosimetry. Pulsed and continuous wave OSL studies recently carried out on alpha-Al2O3:C have shown that the material seems to be the most promising for routine application of OSL for dosimetric purposes. The main objective of the study is to propose a new personal dosimetry system using alpha-Al2O3:C by taking advantage of its optical properties and energy dependencies. In the process of the study, a new dose assessment algorithm was developed using artificial neural networks in hopes of achieving a higher degree of accuracy and precision in personal OSL dosimetry system. The original hypothesis of this work is that the spectral information of X- and gamma-ray fields may be obtained by the analysis of the response of a multi-element system. In this study, a feedforward neural network using the error back-propagation method with Bayesian optimization was applied for the response unfolding procedure. The validation of the proposed algorithm was investigated by unfolding the 10 measured responses of alpha-Al2O3:C for arbitrarily mixed photon fields which range from 20 to 662 keV. c2001 Elsevier Science Ltd. All rights reserved.

  13. Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements

    NASA Astrophysics Data System (ADS)

    Zoros, E.; Moutsatsos, A.; Pappas, E. P.; Georgiou, E.; Kollias, G.; Karaiskos, P.; Pantelis, E.

    2017-09-01

    Detector-, field size- and machine-specific correction factors are required for precise dosimetry measurements in small and non-standard photon fields. In this work, Monte Carlo (MC) simulation techniques were used to calculate the k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} and k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors for a series of ionization chambers, a synthetic microDiamond and diode dosimeters, used for reference and/or output factor (OF) measurements in the Gamma Knife Perfexion photon fields. Calculations were performed for the solid water (SW) and ABS plastic phantoms, as well as for a water phantom of the same geometry. MC calculations for the k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors in SW were compared against corresponding experimental results for a subset of ionization chambers and diode detectors. Reference experimental OF data were obtained through the weighted average of corresponding measurements using TLDs, EBT-2 films and alanine pellets. k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} values close to unity (within 1%) were calculated for most of ionization chambers in water. Greater corrections of up to 6.0% were observed for chambers with relatively large air-cavity dimensions and steel central electrode. A phantom correction of 1.006 and 1.024 (breaking down to 1.014 from the ABS sphere and 1.010 from the accompanying ABS phantom adapter) were calculated for the SW and ABS phantoms, respectively, adding up to k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} corrections in water. Both measurements and MC calculations for the diode and microDiamond detectors resulted in lower than unit k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors, due to their denser sensitive volume and encapsulation materials. In comparison, higher than unit k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} results for the ionization chambers suggested field size depended dose underestimations (being significant for the 4 mm field), with magnitude depending on the combination of

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

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

    PubMed

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

    2013-10-07

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

  17. 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.

  18. Food irradiation dosimetry by opti-chromic technique

    NASA Astrophysics Data System (ADS)

    Zhan-Jun, Liu; Radak, B. B.; McLaughlin, W. L.

    The measurement of gamma-radiation quantities, e.g., absorbed dose in materials such as water, plastics, foodstuffs, is a convenient means of quality assurance in radiation processing. A new dosimetry system, called the "Opti-Chromic" dosimeter, is commercially available in large batches for use as a routine measurement system in the absorbed dose range 10 to 2x10 4 Gy. This dose range covers most food irradiation applications. A statistical evaluation was made of the reproducibility of this dosimeter for measuring doses appropriate for the disinfestation and shelf-life extension of many foods, namely 10 to 2x10 3 Gy. In addition, the small dosimeters were used to map absorbed dose distributions in boxes of foods having four different bulk densities (grapefruit, lemons, peanuts, and wheat bran). It is demonstrated that the dosimeters are rugged and stable enough to be used over a wide temperature and humidity range, and, in fact, can be placed in such environments as the inside of citrus fruits without adverse effects on their ability to give satisfactory dose assessment.

  19. 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.

  20. COMPARISON OF RESPONSE OF PASSIVE DOSIMETRY SYSTEMS IN SCANNING PROTON RADIOTHERAPY-A STUDY USING PAEDIATRIC ANTHROPOMORPHIC PHANTOMS.

    PubMed

    Kneževic, Ž; Ambrozova, I; Domingo, C; De Saint-Hubert, M; Majer, M; Martínez-Rovira, I; Miljanic, S; Mojzeszek, N; Porwol, P; Ploc, O; Romero-Expósito, M; Stolarczyk, L; Trinkl, S; Harrison, R M; Olko, P

    2017-11-18

    Proton beam therapy has advantages in comparison to conventional photon radiotherapy due to the physical properties of proton beams (e.g. sharp distal fall off, adjustable range and modulation). In proton therapy, there is the possibility of sparing healthy tissue close to the target volume. This is especially important when tumours are located next to critical organs and while treating cancer in paediatric patients. On the other hand, the interactions of protons with matter result in the production of secondary radiation, mostly neutrons and gamma radiation, which deposit their energy at a distance from the target. The aim of this study was to compare the response of different passive dosimetry systems in mixed radiation field induced by proton pencil beam inside anthropomorphic phantoms representing 5 and 10 years old children. Doses were measured in different organs with thermoluminescent (MTS-7, MTS-6 and MCP-N), radiophotoluminescent (GD-352 M and GD-302M), bubble and poly-allyl-diglycol carbonate (PADC) track detectors. Results show that RPL detectors are the less sensitive for neutrons than LiF TLDs and can be applied for in-phantom dosimetry of gamma component. Neutron doses determined using track detectors, bubble detectors and pairs of MTS-7/MTS-6 are consistent within the uncertainty range. This is the first study dealing with measurements on child anthropomorphic phantoms irradiated by a pencil scanning beam technique. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Biological dosimetry by interphase chromosome painting.

    PubMed

    Durante, M; George, K; Yang, T C

    1996-01-01

    Both fluorescence in situ hybridization of metaphase spreads with whole-chromosome probes and premature chromosome condensation in interphase nuclei have been used in the past to estimate the radiation dose to lymphocytes. We combined these techniques to evaluate the feasibility of using painted interphase chromosomes for biodosimetry. Human peripheral lymphocytes were exposed to gamma rays and fused to mitotic Chinese hamster cells either immediately after irradiation or after 8 h incubation at 37 degrees C. Interphase or metaphase human chromosomes were hybridized with a composite probe specific for human chromosomes 3 and 4. The dose-response curve for fragment induction immediately after irradiation was linear; these results reflected breakage frequency in the total genome in terms of DNA content per chromosome. At 8 h after irradiation, the dose-response curve for chromosome interchanges, the prevalent aberration in interphase chromosomes, was linear-quadratic and similar to that observed for metaphase chromosomes. These results suggest that painting prematurely condensed chromosomes can be useful for biological dosimetry when blood samples are available shortly after the exposure, or when interphase cells are to be scored instead of mitotic cells.

  2. Biological dosimetry by interphase chromosome painting

    NASA Technical Reports Server (NTRS)

    Durante, M.; George, K.; Yang, T. C.

    1996-01-01

    Both fluorescence in situ hybridization of metaphase spreads with whole-chromosome probes and premature chromosome condensation in interphase nuclei have been used in the past to estimate the radiation dose to lymphocytes. We combined these techniques to evaluate the feasibility of using painted interphase chromosomes for biodosimetry. Human peripheral lymphocytes were exposed to gamma rays and fused to mitotic Chinese hamster cells either immediately after irradiation or after 8 h incubation at 37 degrees C. Interphase or metaphase human chromosomes were hybridized with a composite probe specific for human chromosomes 3 and 4. The dose-response curve for fragment induction immediately after irradiation was linear; these results reflected breakage frequency in the total genome in terms of DNA content per chromosome. At 8 h after irradiation, the dose-response curve for chromosome interchanges, the prevalent aberration in interphase chromosomes, was linear-quadratic and similar to that observed for metaphase chromosomes. These results suggest that painting prematurely condensed chromosomes can be useful for biological dosimetry when blood samples are available shortly after the exposure, or when interphase cells are to be scored instead of mitotic cells.

  3. 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

  4. 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.

  5. 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.

  6. Portal dosimetry for VMAT using integrated images obtained during treatment

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

    Bedford, James L., E-mail: James.Bedford@icr.ac.uk; Hanson, Ian M.; Hansen, Vibeke Nordmark

    2014-02-15

    Purpose: Portal dosimetry provides an accurate and convenient means of verifying dose delivered to the patient. A simple method for carrying out portal dosimetry for volumetric modulated arc therapy (VMAT) is described, together with phantom measurements demonstrating the validity of the approach. Methods: Portal images were predicted by projecting dose in the isocentric plane through to the portal image plane, with exponential attenuation and convolution with a double-Gaussian scatter function. Appropriate parameters for the projection were selected by fitting the calculation model to portal images measured on an iViewGT portal imager (Elekta AB, Stockholm, Sweden) for a variety of phantommore » thicknesses and field sizes. This model was then used to predict the portal image resulting from each control point of a VMAT arc. Finally, all these control point images were summed to predict the overall integrated portal image for the whole arc. The calculated and measured integrated portal images were compared for three lung and three esophagus plans delivered to a thorax phantom, and three prostate plans delivered to a homogeneous phantom, using a gamma index for 3% and 3 mm. A 0.6 cm{sup 3} ionization chamber was used to verify the planned isocentric dose. The sensitivity of this method to errors in monitor units, field shaping, gantry angle, and phantom position was also evaluated by means of computer simulations. Results: The calculation model for portal dose prediction was able to accurately compute the portal images due to simple square fields delivered to solid water phantoms. The integrated images of VMAT treatments delivered to phantoms were also correctly predicted by the method. The proportion of the images with a gamma index of less than unity was 93.7% ± 3.0% (1SD) and the difference between isocenter dose calculated by the planning system and measured by the ionization chamber was 0.8% ± 1.0%. The method was highly sensitive to errors in monitor units

  7. Flat Ge-doped optical fibres for food irradiation dosimetry

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

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dosemore » response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.« less

  8. Flat Ge-doped optical fibres for food irradiation dosimetry

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-04-01

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  9. Internal exposure to neutron-activated 56Mn dioxide powder in Wistar rats: part 1: dosimetry.

    PubMed

    Stepanenko, Valeriy; Rakhypbekov, Tolebay; Otani, Keiko; Endo, Satoru; Satoh, Kenichi; Kawano, Noriyuki; Shichijo, Kazuko; Nakashima, Masahiro; Takatsuji, Toshihiro; Sakaguchi, Aya; Kato, Hiroaki; Onda, Yuichi; Fujimoto, Nariaki; Toyoda, Shin; Sato, Hitoshi; Dyussupov, Altay; Chaizhunusova, Nailya; Sayakenov, Nurlan; Uzbekov, Darkhan; Saimova, Aisulu; Shabdarbaeva, Dariya; Skakov, Mazhin; Vurim, Alexandr; Gnyrya, Vyacheslav; Azimkhanov, Almas; Kolbayenkov, Alexander; Zhumadilov, Kasym; Kairikhanova, Yankar; Kaprin, Andrey; Galkin, Vsevolod; Ivanov, Sergey; Kolyzhenkov, Timofey; Petukhov, Aleksey; Yaskova, Elena; Belukha, Irina; Khailov, Artem; Skvortsov, Valeriy; Ivannikov, Alexander; Akhmedova, Umukusum; Bogacheva, Viktoria; Hoshi, Masaharu

    2017-03-01

    There were two sources of ionizing irradiation after the atomic bombings of Hiroshima and Nagasaki: (1) initial gamma-neutron irradiation at the moment of detonation and (2) residual radioactivity. Residual radioactivity consisted of two components: radioactive fallout containing fission products, including radioactive fissile materials from nuclear device, and neutron-activated radioisotopes from materials on the ground. The dosimetry systems DS86 and DS02 were mainly devoted to the assessment of initial radiation exposure to neutrons and gamma rays, while only brief considerations were given for the estimation of doses caused by residual radiation exposure. Currently, estimation of internal exposure of atomic bomb survivors due to dispersed radioactivity and neutron-activated radioisotopes from materials on the ground is a matter of some interest, in Japan. The main neutron-activated radionuclides in soil dust were 24 Na, 28 Al, 31 Si, 32 P, 38 Cl, 42 K, 45 Ca, 46 Sc, 56 Mn, 59 Fe, 60 Co, and 134 Cs. The radionuclide 56 Mn (T 1/2 = 2.58 h) is known as one of the dominant beta- and gamma emitters during the first few hours after neutron irradiation of soil and other materials on ground, dispersed in the form of dust after a nuclear explosion in the atmosphere. To investigate the peculiarities of biological effects of internal exposure to 56 Mn in comparison with external gamma irradiation, a dedicated experiment with Wistar rats exposed to neutron-activated 56 Mn dioxide powder was performed recently by Shichijo and coworkers. The dosimetry required for this experiment is described here. Assessment of internal radiation doses was performed on the basis of measured 56 Mn activity in the organs and tissues of the rats and of absorbed fractions of internal exposure to photons and electrons calculated with the MCNP-4C Monte Carlo using a mathematical rat phantom. The first results of this international multicenter study show that the internal irradiation due to

  10. 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

  11. SU-E-T-77: Comparison of 2D and 3D Gamma Analysis in Patient-Specific QA for Prostate VMAT Plans

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

    Clemente, F; Perez, C

    2014-06-01

    Purpose: Patient-specific QA procedures for IMRT and VMAT are traditionally performed by comparing TPS calculations with measured single point values and plane dose distributions by means of gamma analysis. New QA devices permit us to calculate 3D dose distributions on patient anatomy as redundant secondary check and reconstruct it from measurements taken with 2D and 3D detector arrays. 3D dose calculations allow us to perform DVH-based comparisons with clinical relevance, as well as 3D gamma analysis. One of these systems (Compass, IBA Dosimetry) combines traditional 2D with new anatomical-based 3D gamma analysis. This work shows the ability of this systemmore » by comparing 2D and 3D gamma analysis in pre-treatment QA for several VMAT prostate plans. Methods: Compass is capable of calculating dose as secondary check from DICOM TPS data and reconstructing it from measurements taken by a 2D ion chamber array (MatriXX Evolution, IBA Dosimetry). Both 2D and 3D gamma tests are available to compare calculated and reconstructed dose in Compass with TPS RT Dose. Results: 15 VMAT prostate plans have been measured with Compass. Dose is reconstructed with Compass for these plans. 2D gamma comparisons can be done for any plane from dose matrix. Mean gamma passing rates for isocenter planes (axial, coronal, sagittal) are (99.7±0.2)%, (99.9±0.1)%, (99.9±0.1)% for reconstructed dose planes. 3D mean gamma passing rates are (98.5±1.7)% for PTVs, (99.1±1.5)% for rectum, (100.0±0.0)% for bladder, (99.6±0.7)% for femoral heads and (98.1±4.1)% for penile bulb. Conclusion: Compass is a powerful tool to perform a complete pre-treatment QA analysis, from 2D techniques to 3D DVH-based techniques with clinical relevance. All reported values for VMAT prostate plans are in good agreement with TPS values. This system permits us to ensure the accuracy in the delivery of VMAT treatments completing a full patient-specific QA program.« less

  12. 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.

  13. SU-F-T-571: Objective Assessment of 3D Dosimetry for Flattened and Flattened Filter Free Stereotactic Rotational Delivery Using 729-Array Detector with Octavius 4D Phantom

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

    Vikraman, S; Arun, C; Jain, K Sandeep

    2016-06-15

    Purpose: The purpose of this study was to assess the potential of 3D dosimetry for flattened and flattened filter free stereotactic rotational delivery in high definition MLC using 729-detector array with Octavius 4D phantom Methods: Twenty rapid arc plans were assessed for this study. For each patient two plans for 6X and 6FFF photon beams were generated with same prescription and critical organ constraints in Eclipse TPS version 13.0 using high definition MLC. Verification plans were generated in scanned Octavius 4D phantom in TPS. 3D dose measurements were collected from 729-ion chamber detector array in Octavius 4D phantom using verisoftmore » software v 6.0. TPS calculated dose was compared with measured 3D dose in verisoft using the following gamma analysis parameters such as 3D volumetric, 3D planar and 2D global gamma in transverse, sagittal and coronal planes for 3mm/3% and 2mm/2% distance to agreement criteria.Passing rate and arithmetic mean of global gamma were analysed for 2D and 3D global gamma in all planes. Results: The average number of dose points passing rate for 2D global gamma with 3mm/3% criteria in transverse, sagittal and coronal planes was 99.06%±2.89%, 98.8%±0.88% and 99.06%±91%, respectively. For 2mm/2% criteria 97.86%±2.26%, 94.49± 2.64% and 94.34%±2.9% was observed. In 3D planar global gamma with 3mm/3% was 99.53%±0.49%, 98.93%±1.03% and 99.29%±1.29%, for 2mm 2% criteria was 97.50%±2.24%, 94.5%±2.5% and 95.38%±4.5%. The maximum arithmetic mean gamma deviation of 0.505%±0.13% was observed in coronal plane for 2D global gamma with 2mm/2% criteria. The 3D volumetric gamma passing rate was observed as 99.61%±0.433% for 3mm /3% and 95.91%±2.51% for 2mm/2%. Conclusion: The objective assessment of 3D dosimetry have demonstrated that the rotational delivery accuracy for flattened and flattened filter free stereotactic plans can be verified by using Octavius system comprising with 729 ion chamber array and Octavius 4D phantom.« less

  14. 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.

  15. SU-C-201-02: Dosimetric Verification of SBRT with FFF-VMAT Using a 3-D Radiochromic/Optical-CT Dosimetry System

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

    Na, Y; Black, P; Wuu, C

    2016-06-15

    Purpose: With an increasing use of small field size and high dose rate irradiation in the advances of radiotherapy techniques, such as stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS), an in-depth quality assurance (QA) system is required. The purpose of this study is to investigate a high resolution optical CT-based 3D radiochromic dosimetry system for SBRT with intensity modulated radiotherapy (IMRT) and flattening filter free (FFF) volumetric modulated arc therapy (VMAT). Methods: Cylindrical PRESAGE radiochromic dosimeters of 10cm height and 11cm diameter were used to validate SBRT. Four external landmarks were placed on the surface of each dosimeter tomore » define the isocenter of target. SBRT plans were delivered using a Varian TrueBeam™ linear accelerator (LINAC). Three validation plans, SBRT with IMRT (6MV 600MU/min), FFF-VMAT (10MV 2400MU/min), and mixed FFF-VMAT (6MV 1400MU/min, 10MV 2400MU/min), were delivered to the PRESAGE dosimeters. Each irradiated PRESAGE dosimeter was scanned using a single laser beam optical CT scanner and reconstructed with a 1mm × 1mm high spatial resolution. The comparison of measured dose distributions of irradiated PRESAGE dosimeters to those calculated by Pinnacle{sup 3} treatment planning system (TPS) were performed with a 10% dose threshold, 3% dose difference (DD), and 3mm distance-to-agreement (DTA) Gamma criteria. Results: The average pass rates for the gamma comparisons between PRESAGE and Pinnacle{sup 3} in the transverse, sagittal, coronal planes were 94.6%, 95.9%, and 96.4% for SBRT with IMRT, FFF-VMAT, and mixed FFF-VMAT plans, respectively. A good agreement of the isodose distributions of those comparisons were shown at the isodose lines 50%, 70%, 80%, 90% and 98%. Conclusion: This study demonstrates the feasibility of the high resolution optical CT-based 3D radiochromic dosimetry system for validation of SBRT with IMRT and FFF-VMAT. This dosimetry system offers higher precision QA

  16. 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.

  17. Feasibility of a high-speed gamma-camera design using the high-yield-pileup-event-recovery method.

    PubMed

    Wong, W H; Li, H; Uribe, J; Baghaei, H; Wang, Y; Yokoyama, S

    2001-04-01

    Higher count-rate gamma cameras than are currently used are needed if the technology is to fulfill its promise in positron coincidence imaging, radionuclide therapy dosimetry imaging, and cardiac first-pass imaging. The present single-crystal design coupled with conventional detector electronics and the traditional Anger-positioning algorithm hinder higher count-rate imaging because of the pileup of gamma-ray signals in the detector and electronics. At an interaction rate of 2 million events per second, the fraction of nonpileup events is < 20% of the total incident events. Hence, the recovery of pileup events can significantly increase the count-rate capability, increase the yield of imaging photons, and minimize image artifacts associated with pileups. A new technology to significantly enhance the performance of gamma cameras in this area is introduced. We introduce a new electronic design called high-yield-pileup-event-recovery (HYPER) electronics for processing the detector signal in gamma cameras so that the individual gamma energies and positions of pileup events, including multiple pileups, can be resolved and recovered despite the mixing of signals. To illustrate the feasibility of the design concept, we have developed a small gamma-camera prototype with the HYPER-Anger electronics. The camera has a 10 x 10 x 1 cm NaI(Tl) crystal with four photomultipliers. Hot-spot and line sources with very high 99mTc activities were imaged. The phantoms were imaged continuously from 60,000 to 3,500,000 counts per second to illustrate the efficacy of the method as a function of counting rates. At 2-3 million events per second, all phantoms were imaged with little distortion, pileup, and dead-time loss. At these counting rates, multiple pileup events (> or = 3 events piling together) were the predominate occurrences, and the HYPER circuit functioned well to resolve and recover these events. The full width at half maximum of the line-spread function at 3,000,000 counts per

  18. 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.

  19. Confirmation of a realistic reactor model for BNCT dosimetry at the TRIGA Mainz

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

    Ziegner, Markus, E-mail: Markus.Ziegner.fl@ait.ac.at; Schmitz, Tobias; Hampel, Gabriele

    2014-11-01

    Purpose: In order to build up a reliable dose monitoring system for boron neutron capture therapy (BNCT) applications at the TRIGA reactor in Mainz, a computer model for the entire reactor was established, simulating the radiation field by means of the Monte Carlo method. The impact of different source definition techniques was compared and the model was validated by experimental fluence and dose determinations. Methods: The depletion calculation code ORIGEN2 was used to compute the burn-up and relevant material composition of each burned fuel element from the day of first reactor operation to its current core. The material composition ofmore » the current core was used in a MCNP5 model of the initial core developed earlier. To perform calculations for the region outside the reactor core, the model was expanded to include the thermal column and compared with the previously established ATTILA model. Subsequently, the computational model is simplified in order to reduce the calculation time. Both simulation models are validated by experiments with different setups using alanine dosimetry and gold activation measurements with two different types of phantoms. Results: The MCNP5 simulated neutron spectrum and source strength are found to be in good agreement with the previous ATTILA model whereas the photon production is much lower. Both MCNP5 simulation models predict all experimental dose values with an accuracy of about 5%. The simulations reveal that a Teflon environment favorably reduces the gamma dose component as compared to a polymethyl methacrylate phantom. Conclusions: A computer model for BNCT dosimetry was established, allowing the prediction of dosimetric quantities without further calibration and within a reasonable computation time for clinical applications. The good agreement between the MCNP5 simulations and experiments demonstrates that the ATTILA model overestimates the gamma dose contribution. The detailed model can be used for the planning of

  20. 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

  1. 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.

  2. Organic Scintillator for Real-Time Neutron Dosimetry

    DOE PAGES

    Beyer, Kyle A.; Di Fulvio, Angela; Stolarczyk, Liliana; ...

    2017-11-15

    We have developed a radiation detector based on an organic scintillator for spectrometry and dosimetry of out-of-field secondary neutrons from clinical proton beams. The detector consists of an EJ-299-34 crystalline organic scintillator, coupled by fiber optic cable to a silicon photomultiplier (SiPM). Proof of concept measurements were taken with 137Cs and 252Cf, and corresponding simulations were performed in MCNPX-PoliMi. Despite its small size, the detector is able to discriminate between neutron and gamma-rays via pulse shape discrimination. We simulated the response function of the detector to monoenergetic neutrons in the 100 keV–0 MeV range using MCNPX-PoliMi. The measured unfolded 252Cfmore » neutron spectrum is in good agreement with the theoretical Watt fission spectrum. We determined the ambient dose equivalent by folding the spectrum with the fluence-to-ambient dose conversion coefficient, with a 1.4% deviation from theory. Some preliminary proton beam experiments were preformed at the Bronowice Cyclotron Center patient treatment facility using a clinically relevant proton pencil beam for brain tumor and craino-spinal treatment directed at a child phantom.« less

  3. Organic Scintillator for Real-Time Neutron Dosimetry

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

    Beyer, Kyle A.; Di Fulvio, Angela; Stolarczyk, Liliana

    We have developed a radiation detector based on an organic scintillator for spectrometry and dosimetry of out-of-field secondary neutrons from clinical proton beams. The detector consists of an EJ-299-34 crystalline organic scintillator, coupled by fiber optic cable to a silicon photomultiplier (SiPM). Proof of concept measurements were taken with 137Cs and 252Cf, and corresponding simulations were performed in MCNPX-PoliMi. Despite its small size, the detector is able to discriminate between neutron and gamma-rays via pulse shape discrimination. We simulated the response function of the detector to monoenergetic neutrons in the 100 keV–0 MeV range using MCNPX-PoliMi. The measured unfolded 252Cfmore » neutron spectrum is in good agreement with the theoretical Watt fission spectrum. We determined the ambient dose equivalent by folding the spectrum with the fluence-to-ambient dose conversion coefficient, with a 1.4% deviation from theory. Some preliminary proton beam experiments were preformed at the Bronowice Cyclotron Center patient treatment facility using a clinically relevant proton pencil beam for brain tumor and craino-spinal treatment directed at a child phantom.« less

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. TH-CD-BRA-02: 3D Remote Dosimetry for MRI-Guided Radiation Therapy: A Hybrid Approach

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

    Rankine, L; The University of North Carolina at Chapel Hill, Chapel Hill, NC; Mein, S

    2016-06-15

    Purpose: To validate the dosimetric accuracy of a commercially available MR-IGRT system using a combination of 3D dosimetry measurements (with PRESAGE(R) radiochromic plastic and optical-CT readout) and an in-house developed GPU-accelerated PENELOPE Monte-Carlo dose calculation system. Methods: {sup 60}Co IMRT subject to a 0.35T lateral magnetic field has recently been commissioned in our institution following AAPM’s TG-119 recommendations. We performed PRESAGE(R) sensitivity studies in 4ml cuvettes to verify linearity, MR-compatibility, and energy-independence. Using 10cm diameter PRESAGE(R), we delivered an open calibration field to examine the percent depth dose and a symmetrical 3-field plan with three adjacent regions of varying dosemore » to determine uniformity within the dosimeter under a magnetic field. After initial testing, TG-119 plans were created in the TPS and then delivered to 14.5cm 2kg PRESAGE(R) dosimeters. Dose readout was performed via optical-CT at a second institution specializing in remote 3D dosimetry. Absolute dose was measured using an IBA CC01 ion chamber and the institution standard patient-specific QA methods were used to validate plan delivery. Calculated TG-119 plans were then compared with an independent Monte Carlo dose calculation (gPENELOPE). Results: PRESAGE(R) responds linearly (R{sup 2}=0.9996) to {sup 60}Co irradiation, in the presence of a 0.35T magnetic field, with a sensitivity of 0.0305(±0.003)cm{sup −1}Gy{sup −1}, within 1% of a 6MV non-MR linac irradiation (R{sup 2}=0.9991) with a sensitivity of 0.0302(±0.003)cm{sup −1}Gy{sup −1}. Analysis of TG-119 clinical plans using 3D-gamma (3%/3mm, 10% threshold) give passing rates of: HN 99.1%, prostate 98.0%, C-shape 90.8%, and multi-target 98.5%. The TPS agreed with gPENELOPE with a mean gamma passing rate of 98.4±1.5% (2%/2mm) with the z-score distributions following a standard normal distribution. Conclusion: We demonstrate for the first time that 3D remote

  11. 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

  12. 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.

  13. 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.

  14. Reactor Dosimetry Applications Using RAPTOR-M3G:. a New Parallel 3-D Radiation Transport Code

    NASA Astrophysics Data System (ADS)

    Longoni, Gianluca; Anderson, Stanwood L.

    2009-08-01

    The numerical solution of the Linearized Boltzmann Equation (LBE) via the Discrete Ordinates method (SN) requires extensive computational resources for large 3-D neutron and gamma transport applications due to the concurrent discretization of the angular, spatial, and energy domains. This paper will discuss the development RAPTOR-M3G (RApid Parallel Transport Of Radiation - Multiple 3D Geometries), a new 3-D parallel radiation transport code, and its application to the calculation of ex-vessel neutron dosimetry responses in the cavity of a commercial 2-loop Pressurized Water Reactor (PWR). RAPTOR-M3G is based domain decomposition algorithms, where the spatial and angular domains are allocated and processed on multi-processor computer architectures. As compared to traditional single-processor applications, this approach reduces the computational load as well as the memory requirement per processor, yielding an efficient solution methodology for large 3-D problems. Measured neutron dosimetry responses in the reactor cavity air gap will be compared to the RAPTOR-M3G predictions. This paper is organized as follows: Section 1 discusses the RAPTOR-M3G methodology; Section 2 describes the 2-loop PWR model and the numerical results obtained. Section 3 addresses the parallel performance of the code, and Section 4 concludes this paper with final remarks and future work.

  15. 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.

  16. 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

  17. Detector for imaging and dosimetry of laser-driven epithermal neutrons by alpha conversion

    NASA Astrophysics Data System (ADS)

    Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Wilson, L. A.; Ansell, S.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Notley, M.; Raspino, D.; Rusby, D. R.; Borghesi, M.; Rhodes, N. J.; McKenna, P.; Neely, D.; Brenner, C. M.; Kar, S.

    2016-10-01

    An epithermal neutron imager based on detecting alpha particles created via boron neutron capture mechanism is discussed. The diagnostic mainly consists of a mm thick Boron Nitride (BN) sheet (as an alpha converter) in contact with a non-borated cellulose nitride film (LR115 type-II) detector. While the BN absorbs the neutrons in the thermal and epithermal ranges, the fast neutrons register insignificantly on the detector due to their low neutron capture and recoil cross-sections. The use of solid-state nuclear track detectors (SSNTD), unlike image plates, micro-channel plates and scintillators, provide safeguard from the x-rays, gamma-rays and electrons. The diagnostic was tested on a proof-of-principle basis, in front of a laser driven source of moderated neutrons, which suggests the potential of using this diagnostic (BN+SSNTD) for dosimetry and imaging applications.

  18. 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%).

  19. 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

  20. 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

  1. 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'.

  2. 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

  3. 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.

  4. ORGANIC SCINTILLATOR FOR REAL-TIME NEUTRON DOSIMETRY.

    PubMed

    Beyer, Kyle A; Di Fulvio, Angela; Stolarczyk, Liliana; Parol, Wiktor; Mojzeszek, Natalia; Kopéc, Renata; Clarke, Shaun D; Pozzi, Sara A

    2017-11-15

    We developed a radiation detector based on an organic scintillator for spectrometry and dosimetry of out-of-field secondary neutrons from clinical proton beams. The detector consists of an EJ-299-34 crystalline organic scintillator, coupled by fiber optic cable to a silicon photomultiplier (SiPM). Proof of concept measurements were taken with 137Cs and 252Cf, and corresponding simulations were performed in MCNPX-PoliMi. Despite its small size, the detector is able to discriminate between neutron and gamma-rays via pulse shape discrimination. We simulated the response function of the detector to monoenergetic neutrons in the 100 keV-0 MeV range using MCNPX-PoliMi. The measured unfolded 252Cf neutron spectrum is in good agreement with the theoretical Watt fission spectrum. We determined the ambient dose equivalent by folding the spectrum with the fluence-to-ambient dose conversion coefficient, with a 1.4% deviation from theory. Some preliminary proton beam experiments were preformed at the Bronowice Cyclotron Center patient treatment facility using a clinically relevant proton pencil beam for brain tumor and craino-spinal treatment directed at a child phantom. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. 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

  6. TH-CD-201-05: Characterization of a Novel Light-Collimating Tank Optical-CT System for 3D Dosimetry

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

    Miles, D; Yoon, S; Adamovics, J

    Purpose: Comprehensive 3D dosimetry is highly desirable for advanced clinical QA, but costly optical readout techniques have hindered widespread implementation. Here, we present the first results from a cost-effective Integrated-lens Dry-tank Optical Scanner (IDOS), designed for convenient 3D dosimetry readout of radiochromic plastic dosimeters (e.g. PRESAGE). Methods: The scanner incorporates a novel transparent light-collimating tank, which collimates a point light source into parallel-ray CT geometry. The tank was designed using an in-house Monte-Carlo optical ray-tracing simulation, and was cast in polyurethane using a 3D printed mould. IDOS spatial accuracy was evaluated by imaging a set of custom optical phantoms, withmore » comparison to x-ray CT images. IDOS dose measurement performance was assessed by imaging PRESAGE dosimeters irradiated with simple known dose distributions (e.g., 4 field box 6MV treatment with Varian Linac). Direct comparisons were made to images from our gold standard DLOS scanner and calculated dose distributions from a commissioned Eclipse planning system. Results: All optical CT images were reconstructed at 1mm isotropic resolution. Comparison of IDOS and x-ray CT images of the geometric phantom demonstrated excellent IDOS geometric accuracy (sub-mm) throughout the dosimeter. IDOS measured 3D dose distribution agreed well with prediction from Eclipse, with 95% gamma pass rate at 3%/3mm. Cross-scanner dose measurement gamma analysis shows >90% of pixels passing at 3%/3mm. Conclusion: The first prototype of the IDOS system has demonstrated promising performance, with accurate dosimeter readout and negligible spatial distortion. The use of optical simulations and 3D printing to create a light collimating-tank has dramatically increased convenience and reduced costs by removing the need for expensive lenses and large volumes of refractive matching fluids.« less

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. Z{gamma}{gamma}{gamma} {yields} 0 Processes in SANC

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

    Bardin, D. Yu., E-mail: bardin@nu.jinr.ru; Kalinovskaya, L. V., E-mail: kalinov@nu.jinr.ru; Uglov, E. D., E-mail: corner@nu.jinr.ru

    2013-11-15

    We describe the analytic and numerical evaluation of the {gamma}{gamma} {yields} {gamma}Z process cross section and the Z {yields} {gamma}{gamma}{gamma} decay rate within the SANC system multi-channel approach at the one-loop accuracy level with all masses taken into account. The corresponding package for numeric calculations is presented. For checking of the results' correctness we make a comparison with the other independent calculations.

  13. Sneaky Gamma-Rays: Using Gravitational Lensing to Avoid Gamma-Gamma-Absorption

    NASA Astrophysics Data System (ADS)

    Boettcher, Markus; Barnacka, Anna

    2014-08-01

    It has recently been suggested that gravitational lensing studies of gamma-ray blazars might be a promising avenue to probe the location of the gamma-ray emitting region in blazars. Motivated by these prospects, we have investigated potential gamma-gamma absorption signatures of intervening lenses in the very-high-energy gamma-ray emission from lensedblazars. We considered intervening galaxies and individual stars within these galaxies. We find that the collective radiation field of galaxies acting as sources of macrolensing are not expected to lead to significant gamma-gamma absorption. Individual stars within intervening galaxies could, in principle, cause a significant opacity to gamma-gamma absorption for VHE gamma-rays if the impact parameter (the distance of closest approach of the gamma-ray to the center of the star) is small enough. However, we find that the curvature of the photon path due to gravitational lensing will cause gamma-ray photons to maintain a sufficiently large distance from such stars to avoid significant gamma-gamma absorption. This re-inforces the prospect of gravitational-lensing studies of gamma-ray blazars without interference due to gamma-gamma absorption due to the lensing objects.

  14. 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

  15. Evaluation of a single-scan protocol for radiochromic film dosimetry.

    PubMed

    Shimohigashi, Yoshinobu; Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Kuwahara, Satoshi; Nagasue, Nozomu; Kai, Yudai

    2015-03-08

    The purpose of this study was to evaluate a single-scan protocol using Gafchromic EBT3 film (EBT3) by comparing it with the commonly used 24-hr measurement protocol for radiochromic film dosimetry. Radiochromic film is generally scanned 24 hr after film exposure (24-hr protocol). The single-scan protocol enables measurement results within a short time using only the verification film, one calibration film, and unirradiated film. The single-scan protocol was scanned 30 min after film irradiation. The EBT3 calibration curves were obtained with the multichannel film dosimetry method. The dose verifications for each protocol were performed with the step pattern, pyramid pattern, and clinical treatment plans for intensity-modulated radiation therapy (IMRT). The absolute dose distributions for each protocol were compared with those calculated by the treatment planning system (TPS) using gamma evaluation at 3% and 3 mm. The dose distribution for the single-scan protocol was within 2% of the 24-hr protocol dose distribution. For the step pattern, the absolute dose discrepancies between the TPS for the single-scan and 24-hr protocols were 2.0 ± 1.8 cGy and 1.4 ± 1.2 cGy at the dose plateau, respectively. The pass rates were 96.0% for the single-scan protocol and 95.9% for the 24-hr protocol. Similarly, the dose discrepancies for the pyramid pattern were 3.6 ± 3.5cGy and 2.9 ± 3.3 cGy, respectively, while the pass rates for the pyramid pattern were 95.3% and 96.4%, respectively. The average pass rates for the four IMRT plans were 96.7% ± 1.8% for the single-scan protocol and 97.3% ± 1.4% for the 24-hr protocol. Thus, the single-scan protocol measurement is useful for dose verification of IMRT, based on its accuracy and efficiency.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. Absorbed dose to water based dosimetry versus air kerma based dosimetry for high-energy photon beams: an experimental study.

    PubMed

    Palmans, Hugo; Nafaa, Laila; De, Jans Jo; Gillis, Sofie; Hoornaert, Marie-Thérèse; Martens, Chantal; Piessens, Marleen; Thierens, Hubert; Van der Plaetsen, Ann; Vynckier, Stefaan

    2002-02-07

    In recent years, a change has been proposed from air kerma based reference dosimetry to absorbed dose based reference dosimetry for all radiotherapy beams of ionizing radiation. In this paper, a dosimetry study is presented in which absorbed dose based dosimetry using recently developed formalisms was compared with air kerma based dosimetry using older formalisms. Three ionization chambers of each of three different types were calibrated in terms of absorbed dose to water and air kerma and sent to five hospitals. There, reference dosimetry with all the chambers was performed in a total of eight high-energy clinical photon beams. The selected chamber types were the NE2571, the PTW-30004 and the Wellhöfer-FC65G (previously Wellhöfer-IC70). Having a graphite wall, they exhibit a stable volume and the presence of an aluminium electrode ensures the robustness of these chambers. The data were analysed with the most important recommendations for clinical dosimetry: IAEA TRS-398, AAPM TG-51, IAEA TRS-277, NCS report-2 (presently recommended in Belgium) and AAPM TG-21. The necessary conversion factors were taken from those protocols, or calculated using the data in the different protocols if data for a chamber type are lacking. Polarity corrections were within 0.1% for all chambers in all beams. Recombination corrections were consistent with theoretical predictions, did not vary within a chamber type and only slightly between different chamber types. The maximum chamber-to-chamber variations of the dose obtained with the different formalisms within the same chamber type were between 0.2% and 0.6% for the NE2571, between 0.2% and 0.6% for the PTW-30004 and 0.1% and 0.3% for the Wellhöfer-FC65G for the different beams. The absorbed dose results for the NE2571 and Wellhöfer-FC65G chambers were in good agreement for all beams and all formalisms. The PTW-30004 chambers gave a small but systematically higher result compared to the result for the NE2571 chambers (on the

  2. Evaluating the Impact of Various Parameters on the Gamma Index Values of 2D Diode Array in IMRT Verification

    PubMed Central

    Jabbari, Keyvan; Pashaei, Fakhereh; Ay, Mohammad R.; Amouheidari, Alireza; Tavakoli, Mohammad B.

    2018-01-01

    Background: MapCHECK2 is a two-dimensional diode arrays planar dosimetry verification system. Dosimetric results are evaluated with gamma index. This study aims to provide comprehensive information on the impact of various factors on the gamma index values of MapCHECK2, which is mostly used for IMRT dose verification. Methods: Seven fields were planned for 6 and 18 MV photons. The azimuthal angle is defined as any rotation of collimators or the MapCHECK2 around the central axis, which was varied from 5 to −5°. The gantry angle was changed from −8 to 8°. Isodose sampling resolution was studied in the range of 0.5 to 4 mm. The effects of additional buildup on gamma index in three cases were also assessed. Gamma test acceptance criteria were 3%/3 mm. Results: The change of azimuthal angle in 5° interval reduced gamma index value by about 9%. The results of putting buildups of various thicknesses on the MapCHECK2 surface showed that gamma index was generally improved in thicker buildup, especially for 18 MV. Changing the sampling resolution from 4 to 2 mm resulted in an increase in gamma index by about 3.7%. The deviation of the gantry in 8° intervals in either directions changed the gamma index only by about 1.6% for 6 MV and 2.1% for 18 MV. Conclusion: Among the studied parameters, the azimuthal angle is one of the most effective factors on gamma index value. The gantry angle deviation and sampling resolution are less effective on gamma index value reduction. PMID:29535922

  3. 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.

  4. Quantitative evaluation of 3D dosimetry for stereotactic volumetric‐modulated arc delivery using COMPASS

    PubMed Central

    Manigandan, Durai; Karrthick, Karukkupalayam Palaniappan; Sambasivaselli, Raju; Senniandavar, Vellaingiri; Ramu, Mahendran; Rajesh, Thiyagarajan; Lutz, Muller; Muthukumaran, Manavalan; Karthikeyan, Nithyanantham; Tejinder, Kataria

    2014-01-01

    The purpose of this study was to evaluate quantitatively the patient‐specific 3D dosimetry tool COMPASS with 2D array MatriXX detector for stereotactic volumetric‐modulated arc delivery. Twenty‐five patients CT images and RT structures from different sites (brain, head & neck, thorax, abdomen, and spine) were taken from CyberKnife Multiplan planning system for this study. All these patients underwent radical stereotactic treatment in CyberKnife. For each patient, linac based volumetric‐modulated arc therapy (VMAT) stereotactic plans were generated in Monaco TPS v3.1 using Elekta Beam Modulator MLC. Dose prescription was in the range of 5–20 Gy per fraction. Target prescription and critical organ constraints were tried to match the delivered treatment plans. Each plan quality was analyzed using conformity index (CI), conformity number (CN), gradient Index (GI), target coverage (TC), and dose to 95% of volume (D95). Monaco Monte Carlo (MC)‐calculated treatment plan delivery accuracy was quantitatively evaluated with COMPASS‐calculated (CCA) dose and COMPASS indirectly measured (CME) dose based on dose‐volume histogram metrics. In order to ascertain the potential of COMPASS 3D dosimetry for stereotactic plan delivery, 2D fluence verification was performed with MatriXX using MultiCube phantom. Routine quality assurance of absolute point dose verification was performed to check the overall delivery accuracy. Quantitative analyses of dose delivery verification were compared with pass and fail criteria of 3 mm and 3% distance to agreement and dose differences. Gamma passing rate was compared with 2D fluence verification from MatriXX with MultiCube. Comparison of COMPASS reconstructed dose from measured fluence and COMPASS computed dose has shown a very good agreement with TPS calculated dose. Each plan was evaluated based on dose volume parameters for target volumes such as dose at 95% of volume (D95) and average dose. For critical organs dose at 20% of

  5. IAEA Co-ordinated Research Project: update of X-ray and gamma-ray decay data standards for detector calibration and other applications.

    PubMed

    Nichols, Alan L

    2004-01-01

    A Co-ordinated Research Project (CRP) was established in 1998 by the IAEA Nuclear Data Section (Update of X-ray and gamma-ray Decay Data Standards for Detector Calibration and Other Applications), in order to improve further the recommended decay data used to undertake efficiency calibrations of gamma-ray detectors. Participants in this CRP reviewed and modified the list of radionuclides most suited for detector efficiency calibration, and also considered the decay-data needs for safeguards, waste management, dosimetry, nuclear medicine, material analysis and environmental monitoring. Overall, 62 radionuclides were selected for decay-data evaluation, along with four parent-daughter combinations and two natural decay chains. gamma-ray emissions from specific nuclear reactions were also included to extend the calibrant energy well beyond 10 MeV. A significant number of these decay-data evaluations have been completed, and an IAEA-TECDOC report and database are in the process of being assembled for planned completion by the end of 2003.

  6. 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.

  7. Initial Nuclear Radiation Hardness Validation Test

    DTIC Science & Technology

    2008-11-03

    d. Dosimetry from the GDR environment. The TLDs should be placed as indicated in the section above and their location used to determine the... electronics to levels which will account for: all error terms in dosimetry and data recording, response differences in microcircuits due to different...the internal gamma dose environment of an LRU. d. Dosimetry from the gamma dose environment. The TLDs should be placed as indicated in the

  8. The Z {yields} cc-bar {yields} {gamma}{gamma}*, Z {yields} bb-bar {yields} {gamma}{gamma}* triangle diagrams and the Z {yields} {gamma}{psi}, Z {yields} {gamma}Y decays

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

    Achasov, N. N., E-mail: achasov@math.nsc.ru

    2011-03-15

    The approach to the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decay study is presented in detail, based on the sum rules for the Z {yields} cc-bar {yields} {gamma}{gamma}* and Z {yields} bb-bar {yields} {gamma}{gamma}* amplitudes and their derivatives. The branching ratios of the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decays are calculated for different hypotheses on saturation of the sum rules. The lower bounds of {Sigma}{sub {psi}} BR(Z {yields} {gamma}{psi}) = 1.95 Multiplication-Sign 10{sup -7} and {Sigma}{sub {upsilon}} BR(Z {yields} {gamma}Y) = 7.23 Multiplication-Sign 10{sup -7} are found. Deviations from the lower bounds are discussed, including the possibilitymore » of BR(Z {yields} {gamma}J/{psi}(1S)) {approx} BR(Z {yields} {gamma}Y(1S)) {approx} 10{sup -6}, that could be probably measured in LHC. The angular distributions in the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decays are also calculated.« less

  9. 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

  10. 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.

  11. Time-resolved in vivo luminescence dosimetry for online error detection in pulsed dose-rate brachytherapy.

    PubMed

    Andersen, Claus E; Nielsen, Søren Kynde; Lindegaard, Jacob Christian; Tanderup, Kari

    2009-11-01

    The purpose of this study is to present and evaluate a dose-verification protocol for pulsed dose-rate (PDR) brachytherapy based on in vivo time-resolved (1 s time resolution) fiber-coupled luminescence dosimetry. Five cervix cancer patients undergoing PDR brachytherapy (Varian GammaMed Plus with 192Ir) were monitored. The treatments comprised from 10 to 50 pulses (1 pulse/h) delivered by intracavitary/interstitial applicators (tandem-ring systems and/or needles). For each patient, one or two dosimetry probes were placed directly in or close to the tumor region using stainless steel or titanium needles. Each dosimeter probe consisted of a small aluminum oxide crystal attached to an optical fiber cable (1 mm outer diameter) that could guide radioluminescence (RL) and optically stimulated luminescence (OSL) from the crystal to special readout instrumentation. Positioning uncertainty and hypothetical dose-delivery errors (interchanged guide tubes or applicator movements from +/-5 to +/-15 mm) were simulated in software in order to assess the ability of the system to detect errors. For three of the patients, the authors found no significant differences (P>0.01) for comparisons between in vivo measurements and calculated reference values at the level of dose per dwell position, dose per applicator, or total dose per pulse. The standard deviations of the dose per pulse were less than 3%, indicating a stable dose delivery and a highly stable geometry of applicators and dosimeter probes during the treatments. For the two other patients, the authors noted significant deviations for three individual pulses and for one dosimeter probe. These deviations could have been due to applicator movement during the treatment and one incorrectly positioned dosimeter probe, respectively. Computer simulations showed that the likelihood of detecting a pair of interchanged guide tubes increased by a factor of 10 or more for the considered patients when going from integrating to time

  12. SU-F-SPS-06: Implementation of a Back-Projection Algorithm for 2D in Vivo Dosimetry with An EPID System

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

    Hernandez Reyes, B; Rodriguez Perez, E; Sosa Aquino, M

    Purpose: To implement a back-projection algorithm for 2D dose reconstructions for in vivo dosimetry in radiation therapy using an Electronic Portal Imaging Device (EPID) based on amorphous silicon. Methods: An EPID system was used to calculate dose-response function, pixel sensitivity map, exponential scatter kernels and beam hardenig correction for the back-projection algorithm. All measurements were done with a 6 MV beam. A 2D dose reconstruction for an irradiated water phantom (30×30×30 cm{sup 3}) was done to verify the algorithm implementation. Gamma index evaluation between the 2D reconstructed dose and the calculated with a treatment planning system (TPS) was done. Results:more » A linear fit was found for the dose-response function. The pixel sensitivity map has a radial symmetry and was calculated with a profile of the pixel sensitivity variation. The parameters for the scatter kernels were determined only for a 6 MV beam. The primary dose was estimated applying the scatter kernel within EPID and scatter kernel within the patient. The beam hardening coefficient is σBH= 3.788×10{sup −4} cm{sup 2} and the effective linear attenuation coefficient is µAC= 0.06084 cm{sup −1}. The 95% of points evaluated had γ values not longer than the unity, with gamma criteria of ΔD = 3% and Δd = 3 mm, and within the 50% isodose surface. Conclusion: The use of EPID systems proved to be a fast tool for in vivo dosimetry, but the implementation is more complex that the elaborated for pre-treatment dose verification, therefore, a simplest method must be investigated. The accuracy of this method should be improved modifying the algorithm in order to compare lower isodose curves.« less

  13. SU-F-T-236: Comparison of Two IMRT/VMAT QA Systems Using Gamma Index Analysis

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

    Dogan, N; Denissova, S

    2016-06-15

    Purpose: The goal of this study is to assess differences in the Gamma index pass rates when using two commercial QA systems and provide optimum Gamma index parameters for pre-treatment patient specific QA. Methods: Twenty-two VMAT cases that consisted of prostate, lung, head and neck, spine, brain and pancreas, were included in this study. The verification plans have been calculated using AcurosXB(V11) algorithm for different dose grids (1.5mm, 2.5mm, 3mm). The measurements were performed on TrueBeam(Varian) accelerator using both EPID(S1000) portal imager and ArcCheck(SunNuclearCorp) devices. Gamma index criteria variation of 3%/3mm, 2%/3mm, 2%/2mm and threshold (TH) doses of 5% tomore » 50% were used in analysis. Results: The differences in Gamma pass rates between two devices are not statistically significant for 3%/3mm, yielding pass rate higher than 95%. Increase of lower dose TH showed reduced pass rates for both devices. ArcCheck’s more pronounced effect can be attributed to higher contribution of lower dose region spread. As expected, tightening criteria to 2%/2mm (TH: 10%) decreased Gamma pass rates below 95%. Higher EPID (92%) pass rates compared to ArcCheck (86%) probably due to better spatial resolution. Portal Dosimetry results showed lower Gamma pass rates for composite plans compared to individual field pass rates. This may be due to the expansion in the analyzed region which includes pixels not included in the separate field analysis. Decreasing dose grid size from 2.5mm to 1.5mm did not show statistically significant (p<0.05) differences in Gamma pass rates for both QA devices. Conclusion: Overall, both system measurements agree well with calculated dose when using gamma index criteria of 3%/3mm for a variety of VMAT cases. Variability between two systems increases using different dose GRID, TH and tighter gamma criteria and must be carefully assessed prior to clinical use.« less

  14. Initial experiments with gel-water: towards MRI-linac dosimetry and imaging.

    PubMed

    Alnaghy, Sarah J; Gargett, Maegan; Liney, Gary; Petasecca, Marco; Begg, Jarrad; Espinoza, Anthony; Newall, Matthew K; Duncan, Mitchell; Holloway, Lois; Lerch, Michael L F; Lazea, Mircea; Rosenfeld, Anatoly B; Metcalfe, Peter

    2016-12-01

    Tracking the position of a moving radiation detector in time and space during data acquisition can replicate 4D image-guided radiotherapy (4DIGRT). Magnetic resonance imaging (MRI)-linacs need MRI-visible detectors to achieve this, however, imaging solid phantoms is an issue. Hence, gel-water, a material that provides signal for MRI-visibility, and which will in future work, replace solid water for an MRI-linac 4DIGRT quality assurance tool, is discussed. MR and CT images of gel-water were acquired for visualisation and electron density verification. Characterisation of gel-water at 0 T was compared to Gammex-RMI solid water, using MagicPlate-512 (M512) and RMI Attix chamber; this included percentage depth dose, tissue-phantom ratio (TPR 20/10 ), tissue-maximum ratio (TMR), profiles, output factors, and a gamma analysis to investigate field penumbral differences. MR images of a non-powered detector in gel-water demonstrated detector visualisation. The CT-determined gel-water electron density agreed with the calculated value of 1.01. Gel-water depth dose data demonstrated a maximum deviation of 0.7% from solid water for M512 and 2.4% for the Attix chamber, and by 2.1% for TPR 20/10 and 1.0% for TMR. FWHM and output factor differences between materials were ≤0.3 and ≤1.4%. M512 data passed gamma analysis with 100% within 2%, 2 mm tolerance for multileaf collimator defined fields. Gel-water was shown to be tissue-equivalent for dosimetry and a feasible option to replace solid water.

  15. 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

  16. [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.

  17. Fricke-gel dosimetry in epithermal or thermal neutron beams of a research reactor

    NASA Astrophysics Data System (ADS)

    Gambarini, G.; Artuso, E.; Giove, D.; Volpe, L.; Agosteo, S.; Barcaglioni, L.; Campi, F.; Garlati, L.; Pola, A.; Durisi, E.; Borroni, M.; Carrara, M.; Klupak, V.; Marek, M.; Viererbl, L.; Vins, M.; d'Errico, F.

    2015-11-01

    Fricke-xylenol-orange gel has shown noticeable potentiality for in-phantom dosimetry in epithermal or thermal neutron fields with very high fluence rate, as those characteristic of nuclear research reactors. Fricke gels in form of layers give the possibility of achieving spatial distribution of gamma dose, fast neutron dose and dose due to charged particles generated by thermal neutron reactions. The thermal neutron fluence has been deduced from the dose coming from the charge particles emitted by neutron reactions with the isotope 10B. Some measurements have been performed for improving the information on the relative sensitivity of Fricke gel dosimeters to the particles produced by 10B reactions, because at present the precision of dose evaluations is limited by the scanty knowledge about the dependence of the dosimeter sensitivity on the radiation LET. For in-air measurements, the dosimeter material can produce an enhancement of thermal neutron fluence. Measurements and Monte Carlo calculations have been developed to investigate the importance of this effect.

  18. Determination of U, Th and K in bricks by gamma-ray spectrometry, X-ray fluorescence analysis and neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Bártová, H.; Kučera, J.; Musílek, L.; Trojek, T.; Gregorová, E.

    2017-11-01

    Knowledge of the content of natural radionuclides in bricks can be important in some cases in dosimetry and application of ionizing radiation. Dosimetry of naturally occurring radionuclides in matter (NORM) in general is one of them, the other one, related to radiation protection, is radon exposure evaluation, and finally, it is needed for the thermoluminescence (TL) dating method. The internal dose rate inside bricks is caused mostly by contributions of the natural radionuclides 238U, 232Th, radionuclides of their decay chains, and 40K. The decay chain of 235U is usually much less important. The concentrations of 238U, 232Th and 40K were measured by various methods, namely by gamma-ray spectrometry, X-ray fluorescence analysis (XRF), and neutron activation analysis (NAA) which was used as a reference method. These methods were compared from the point of view of accuracy, limit of detection (LOD), amount of sample needed and sample handling, time demands, and instrument availability.

  19. 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

  20. 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

  1. Gamma radiation-induced blue shift of resonance peaks of Bragg gratings in pure silica fibres

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

    Faustov, A V; Mégret, P; Wuilpart, M

    2016-02-28

    We report the first observation of a significant gamma radiation-induced blue shift of the reflection/transmission peak of fibre Bragg gratings inscribed into pure-silica core fibres via multiphoton absorption of femtosecond pulses. At a total dose of ∼100 kGy, the shift is ∼20 pm. The observed effect is attributable to the ionising radiation-induced decrease in the density of the silica glass when the rate of colour centre formation is slow. We present results of experimental measurements that provide the key parameters of the dynamics of the gratings for remote dosimetry and temperature sensing. (laser crystals and braggg ratings)

  2. Assessment of Ethylene Vinyl-Acetato Copolymer (EVA) Samples Bombarded by Gamma Radiation via Linearity Analyses

    NASA Astrophysics Data System (ADS)

    de Oliveira, L. N.; do Nascimento, E. O.; Schimidt, F.; Antonio, P. L.; Caldas, L. V. E.

    2018-03-01

    Materials with the potential to become dosimeters are of interest in radiation physics. In this research, the materials were analyzed and compared in relation to their linearity ranges. Samples of ethylene vinyl-acetate copolymer (EVA) were irradiated with doses from 10 Gy to 10 kGy using a 60Co Gamma-Cell system 220 and evaluated with the FTIR technique. The linearity analyses were applied through two methodologies, searching for linear regions in their response. The results show that both applied analyses indicate linear regions in defined dose interval. The radiation detectors EVA can be useful for radiation dosimetry in intermediate and high doses.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. MO-FG-202-06: Improving the Performance of Gamma Analysis QA with Radiomics- Based Image Analysis

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

    Wootton, L; Nyflot, M; Ford, E

    2016-06-15

    Purpose: The use of gamma analysis for IMRT quality assurance has well-known limitations. Traditionally, a simple thresholding technique is used to evaluated passing criteria. However, like any image the gamma distribution is rich in information which thresholding mostly discards. We therefore propose a novel method of analyzing gamma images that uses quantitative image features borrowed from radiomics, with the goal of improving error detection. Methods: 368 gamma images were generated from 184 clinical IMRT beams. For each beam the dose to a phantom was measured with EPID dosimetry and compared to the TPS dose calculated with and without normally distributedmore » (2mm sigma) errors in MLC positions. The magnitude of 17 intensity histogram and size-zone radiomic features were derived from each image. The features that differed most significantly between image sets were determined with ROC analysis. A linear machine-learning model was trained on these features to classify images as with or without errors on 180 gamma images.The model was then applied to an independent validation set of 188 additional gamma distributions, half with and half without errors. Results: The most significant features for detecting errors were histogram kurtosis (p=0.007) and three size-zone metrics (p<1e-6 for each). The sizezone metrics detected clusters of high gamma-value pixels under mispositioned MLCs. The model applied to the validation set had an AUC of 0.8, compared to 0.56 for traditional gamma analysis with the decision threshold restricted to 98% or less. Conclusion: A radiomics-based image analysis method was developed that is more effective in detecting error than traditional gamma analysis. Though the pilot study here considers only MLC position errors, radiomics-based methods for other error types are being developed, which may provide better error detection and useful information on the source of detected errors. This work was partially supported by a grant from the

  8. 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...

  9. Assessment of the accuracy and stability of frameless gamma knife radiosurgery.

    PubMed

    Chung, Hyun-Tai; Park, Woo-Yoon; Kim, Tae Hoon; Kim, Yong Kyun; Chun, Kook Jin

    2018-06-03

    The aim of this study was to assess the accuracy and stability of frameless gamma knife radiosurgery (GKRS). The accuracies of the radiation isocenter and patient couch movement were evaluated by film dosimetry with a half-year cycle. Radiation isocenter assessment with a diode detector and cone-beam computed tomography (CBCT) image accuracy tests were performed daily with a vendor-provided tool for one and a half years after installation. CBCT image quality was examined twice a month with a phantom. The accuracy of image coregistration using CBCT images was studied using magnetic resonance (MR) and computed tomography (CT) images of another phantom. The overall positional accuracy was measured in whole procedure tests using film dosimetry with an anthropomorphic phantom. The positional errors of the radiation isocenter at the center and at an extreme position were both less than 0.1 mm. The three-dimensional deviation of the CBCT coordinate system was stable for one and a half years (mean 0.04 ± 0.02 mm). Image coregistration revealed a difference of 0.2 ± 0.1 mm between CT and CBCT images and a deviation of 0.4 ± 0.2 mm between MR and CBCT images. The whole procedure test of the positional accuracy of the mask-based irradiation revealed an accuracy of 0.5 ± 0.6 mm. The radiation isocenter accuracy, patient couch movement accuracy, and Gamma Knife Icon CBCT accuracy were all approximately 0.1 mm and were stable for one and a half years. The coordinate system assigned to MR images through coregistration was more accurate than the system defined by fiducial markers. Possible patient motion during irradiation should be considered when evaluating the overall accuracy of frameless GKRS. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  10. 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.

  11. Exfoliated graphite with graphene flakes as potential candidates for TL dosimeters at high gamma doses.

    PubMed

    Ortiz-Morales, A; López-González, E; Rueda-Morales, G; Ortega-Cervantez, G; Ortiz-Lopez, J

    2018-06-06

    Graphite powder (GP) subjected to microwave radiation (MWG) results in exfoliation of graphite particles into few-layered graphene flakes (GF) intermixed with partially exfoliated graphite particles (PEG). Characterization of MWG by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Raman spectroscopy reveal few-layer GF with sizes ranging from 0.2 to 5 µm. Raman D, G, and 2D (G') bands characteristic of graphitic structures include evidence of the presence of bilayered graphene. The thermoluminescent (TL) dosimetric properties of MWG are evaluated and can be characterized as a gamma-ray sensitive and dose-resistant material with kinetic parameters (activation energy for the main peak located at 400 and 408 K is 0.69 and 0.72 eV) and threshold dose (~1 kGy and 5 kGy respectively). MWG is a low-Z material (Z eff = 6) with a wide linear range of TL dose-response (0.170-2.5 kGy) tested at doses in the 1-20 kGy range with promising results for applications in gamma-ray dosimetry. Results obtained in gamma irradiated MWG are compared with those obtained in graphite powder samples (GP) without microwave treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. 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.

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

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

    Palmer, A L; University of Surrey, Guildford, Surrey; Bradley, D A

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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. [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.

  20. 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.

  1. Characterization of a fiber-coupled Al2O3:C luminescence dosimetry system for online in vivo dose verification during 192Ir brachytherapy.

    PubMed

    Andersen, Claus E; Nielsen, Søren Kynde; Greilich, Steffen; Helt-Hansen, Jakob; Lindegaard, Jacob Christian; Tanderup, Kari

    2009-03-01

    A prototype of a new dose-verification system has been developed to facilitate prevention and identification of dose delivery errors in remotely afterloaded brachytherapy. The system allows for automatic online in vivo dosimetry directly in the tumor region using small passive detector probes that fit into applicators such as standard needles or catheters. The system measures the absorbed dose rate (0.1 s time resolution) and total absorbed dose on the basis of radioluminescence (RL) and optically stimulated luminescence (OSL) from aluminum oxide crystals attached to optical fiber cables (1 mm outer diameter). The system was tested in the range from 0 to 4 Gy using a solid-water phantom, a Varian GammaMed Plus 192Ir PDR afterloader, and dosimetry probes inserted into stainless-steel brachytherapy needles. The calibrated system was found to be linear in the tested dose range. The reproducibility (one standard deviation) for RL and OSL measurements was 1.3%. The measured depth-dose profiles agreed well with the theoretical expectations computed with the EGSNRC Monte Carlo code, suggesting that the energy dependence for the dosimeter probes (relative to water) is less than 6% for source-to-probe distances in the range of 2-50 mm. Under certain conditions, the RL signal could be greatly disturbed by the so-called stem signal (i.e., unwanted light generated in the fiber cable upon irradiation). The OSL signal is not subject to this source of error. The tested system appears to be adequate for in vivo brachytherapy dosimetry.

  2. Evaluation of a single‐scan protocol for radiochromic film dosimetry

    PubMed Central

    Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Kuwahara, Satoshi; Nagasue, Nozomu; Kai, Yudai

    2015-01-01

    The purpose of this study was to evaluate a single‐scan protocol using Gafchromic EBT3 film (EBT3) by comparing it with the commonly used 24‐hr measurement protocol for radiochromic film dosimetry. Radiochromic film is generally scanned 24 hr after film exposure (24‐hr protocol). The single‐scan protocol enables measurement results within a short time using only the verification film, one calibration film, and unirradiated film. The single‐scan protocol was scanned 30 min after film irradiation. The EBT3 calibration curves were obtained with the multichannel film dosimetry method. The dose verifications for each protocol were performed with the step pattern, pyramid pattern, and clinical treatment plans for intensity‐modulated radiation therapy (IMRT). The absolute dose distributions for each protocol were compared with those calculated by the treatment planning system (TPS) using gamma evaluation at 3% and 3 mm. The dose distribution for the single‐scan protocol was within 2% of the 24‐hr protocol dose distribution. For the step pattern, the absolute dose discrepancies between the TPS for the single‐scan and 24‐hr protocols were 2.0±1.8 cGy and 1.4±1.2 cGy at the dose plateau, respectively. The pass rates were 96.0% for the single‐scan protocol and 95.9% for the 24‐hr protocol. Similarly, the dose discrepancies for the pyramid pattern were 3.6±3.5 cGy and 2.9±3.3 cGy, respectively, while the pass rates for the pyramid pattern were 95.3% and 96.4%, respectively. The average pass rates for the four IMRT plans were 96.7%±1.8% for the single‐scan protocol and 97.3%±1.4% for the 24‐hr protocol. Thus, the single‐scan protocol measurement is useful for dose verification of IMRT, based on its accuracy and efficiency. PACS number: 87.55.Qr PMID:26103194

  3. 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.

  4. Development of a 3D remote dosimetry protocol compatible with MRgIMRT.

    PubMed

    Mein, Stewart; Rankine, Leith; Adamovics, John; Li, Harold; Oldham, Mark

    2017-11-01

    system to evaluate the accuracy of MRgRT in these conditions. In the small volume study, in the presence of a 0.35 T magnetic field, PRESAGE ® was observed to respond linearly (R 2  = 0.9996) to Co-60 irradiation at t = 48 hrs postirradiation, within the dose ranges of 0 to 15 Gy, with a sensitivity of 0.0305(±0.003) ΔOD cm -1  Gy -1 . In the large volume studies, at t = 1 hr postirradiation, consistent linear response was observed, with average sensitivity of 0.0930 ± 0.002 ΔOD cm -1  Gy -1 . However, dosimeters gradually darkened with time (OD< 5% per day). A small radial dependence to the dosimeter sensitivity was measured (< 3% of maximum dose), which is attributed to a spherically symmetric dosimeter artifact arising from exothermic heating legacy in the PRESAGE ® polyurethane substrate during curing. When applied to the TG-119 IMRT irradiations, the remote dosimetry protocol (including correction terms) yielded excellent line-profile and 3D gamma agreement for 3%/3 mm, 10% threshold (mean passing rate = 96.6% ± 4.0%). A novel 3D remote dosimetry protocol is introduced for validating off-site dosimetrically complex radiotherapy systems, including MRgRT. The protocol involves correcting for temporal and spatially dependent changes in PRESAGE ® radiochromic dosimeters readout by optical-CT. Application of the protocol to TG-119 irradiations enabled verification of MRgRT dose distributions with high resolution. © 2017 American Association of Physicists in Medicine.

  5. 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)

  6. 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

  7. 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.

  8. TH-A-204-00: Key Dosimetry Data - Impact of New ICRU Recommendations

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

    NONE

    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 xrays 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

  9. TH-A-204-01: Part I - Key Data for Ionizing-Radiation Dosimetry

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

    Seltzer, S.

    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

  10. 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.

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

    PubMed

    Scalchi, P; Francescon, P

    1998-03-01

    Metal oxide semiconductor field-effect transistor (MOSFET) detectors were calibrated to perform in vivo dosimetry during 6-MV treatments, both in normal setup and total body irradiation (TBI) conditions. MOSFET water-equivalent depth, dependence of the calibration factors (CFs) on the field sizes, MOSFET orientation, bias supply, accumulated dose, incidence angle, temperature, and spoiler-skin distance in TBI setup were investigated. MOSFET reproducibility was verified. The correlation between the water-equivalent midplane depth and the ratio of the exit MOSFET readout divided by the entrance MOSFET readout was studied. MOSFET midplane dosimetry in TBI setup was compared with thermoluminescent dosimetry in an anthropomorphic phantom. By using ionization chamber measurements, the TBI midplane dosimetry was also verified in the presence of cork as a lung substitute. The water-equivalent depth of the MOSFET is about 0.8 mm or 1.8 mm, depending on which sensor side faces the beam. The field size also affects this quantity; Monte Carlo simulations allow driving this behavior by changes in the contaminating electron mean energy. The CFs vary linearly as a function of the square field side, for fields ranging from 5 x 5 to 30 x 30 cm2. In TBI setup, varying the spoiler-skin distance between 5 mm and 10 cm affects the CFs within 5%. The MOSFET reproducibility is about 3% (2 SD) for the doses normally delivered to the patients. The effect of the accumulated dose on the sensor response is negligible. For beam incidence ranging from 0 degrees to 90 degrees, the MOSFET response varies within 7%. No monotonic correlation between the sensor response and the temperature is apparent. Good correlation between the water-equivalent midplane depth and the ratio of the exit MOSFET readout divided by the entrance MOSFET readout was found (the correlation coefficient is about 1). The MOSFET midplane dosimetry relevant to the anthropomorphic phantom irradiation is in agreement with TLD

  12. Three-dimensional radiochromic film dosimetry for volumetric modulated arc therapy using a spiral water phantom.

    PubMed

    Tanooka, Masao; Doi, Hiroshi; Miura, Hideharu; Inoue, Hiroyuki; Niwa, Yasue; Takada, Yasuhiro; Fujiwara, Masayuki; Sakai, Toshiyuki; Sakamoto, Kiyoshi; Kamikonya, Norihiko; Hirota, Shozo

    2013-11-01

    We validated 3D radiochromic film dosimetry for volumetric modulated arc therapy (VMAT) using a newly developed spiral water phantom. The phantom consists of a main body and an insert box, each of which has an acrylic wall thickness of 3 mm and is filled with water. The insert box includes a spiral film box used for dose-distribution measurement, and a film holder for positioning a radiochromic film. The film holder has two parallel walls whose facing inner surfaces are equipped with spiral grooves in a mirrored configuration. The film is inserted into the spiral grooves by its side edges and runs along them to be positioned on a spiral plane. Dose calculation was performed by applying clinical VMAT plans to the spiral water phantom using a commercial Monte Carlo-based treatment-planning system, Monaco, whereas dose was measured by delivering the VMAT beams to the phantom. The calculated dose distributions were resampled on the spiral plane, and the dose distributions recorded on the film were scanned. Comparisons between the calculated and measured dose distributions yielded an average gamma-index pass rate of 87.0% (range, 91.2-84.6%) in nine prostate VMAT plans under 3 mm/3% criteria with a dose-calculation grid size of 2 mm. The pass rates were increased beyond 90% (average, 91.1%; range, 90.1-92.0%) when the dose-calculation grid size was decreased to 1 mm. We have confirmed that 3D radiochromic film dosimetry using the spiral water phantom is a simple and cost-effective approach to VMAT dose verification.

  13. Determination of neutron spectra within the energy of 1 keV to 1 MeV by means of reactor dosimetry

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

    Sergeyeva, Victoria; Destouches, Christophe; Lyoussi, Abdallah

    2015-07-01

    The standard procedure for neutron reactor dosimetry is based on neutron irradiation of a target and its post-irradiation analysis by Gamma and/or X-ray spectrometry. Nowadays, the neutron spectra can be easily characterized for thermal and fast energies (respectively 0.025 eV and >1 MeV). In this work we propose a new target and an innovating post-irradiation technique of analysis in order to detect the neutron spectra within the energy of 1 keV to 1 MeV. This article will present the calculations performed for the selection of a suitable nuclear reaction and isotope, the results predicted by simulations, the irradiation campaign thatmore » is proposed and the post-irradiation technique of analysis. (authors)« less

  14. 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.

  15. 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

  16. 3D printer generated thorax phantom with mobile tumor for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B.

    2015-07-01

    This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor's trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between

  17. 3D printer generated thorax phantom with mobile tumor for radiation dosimetry.

    PubMed

    Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B

    2015-07-01

    This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor's trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between

  18. 3D printer generated thorax phantom with mobile tumor for radiation dosimetry

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

    Mayer, Rulon; Liacouras, Peter; Thomas, Andrew

    2015-07-15

    This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches amore » patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor’s trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement

  19. SU-E-T-647: Quality Assurance of VMAT by Gamma Analysis Dependence On Low-Dose Threshold

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

    Song, J; Kim, M; Lee, S

    2015-06-15

    Purpose: The AAPM TG-119 instructed institutions to use low-dose threshold (LDT) of 10% or a ROI determined by the jaw when they collected gamma analysis QA data of planar dose distribution. Also, based on a survey by Nelms and Simon, more than 70% of institutions use a LDT between 0% and 10% for gamma analysis. However, there are no clinical data to quantitatively demonstrate the impact of the LDT on the gamma index. Therefore, we performed a gamma analysis with LDTs of 0% to 15% according to both global and local normalization and different acceptance criteria: 3%/3 mm, 2%/2 mm,more » and 1%/1 mm. Methods: A total of 30 treatment plans—10 head and neck, 10 brain, and 10 prostate cancer cases—were randomly selected from the Varian Eclipse TPS, retrospectively. For the gamma analysis, a predicted portal image was acquired through a portal dose calculation algorithm in the Eclipse TPS, and a measured portal image was obtained using a Varian Clinac iX and an EPID. Then, the gamma analysis was performed using the Portal Dosimetry software. Results: For the global normalization, the gamma passing rate (%GP) decreased as the LDT increased, and all cases of low-dose thresholds exhibited a %GP above 95% for both the 3%/3 mm and 2%/2 mm criteria. However, for local normalization, the %GP increased as LDT increased. The gamma passing rate with LDT of 10% increased by 6.86%, 9.22% and 6.14% compared with the 0% in the case of the head and neck, brain and prostate for 3%/3 mm criteria, respectively. Conclusion: Applying the LDT in the global normalization does not have critical impact to judge patient-specific QA results. However, LDT for the local normalization should be carefully selected because applying the LDT could affect the average of the %GP to increase rapidly.« less

  20. Evaluation of dose uncertainty in radiation processing using EPR spectroscopy and butylated hydroxytoluene rods as dosimetry system

    NASA Astrophysics Data System (ADS)

    Alkhorayef, M.; Mansour, A.; Sulieman, A.; Alnaaimi, M.; Alduaij, M.; Babikir, E.; Bradley, D. A.

    2017-12-01

    Butylatedhydroxytoluene (BHT) rods represent a potential dosimeter in radiation processing, with readout via electron paramagnetic resonance (EPR) spectroscopy. Among the possible sources of uncertainty are those associated with the performance of the dosimetric medium and the conditions under which measurements are made, including sampling and environmental conditions. Present study makes estimate of the uncertainties, investigating physical response in different resonance regions. BHT, a white crystalline solid with a melting point of between 70-73 °C, was investigated using 60Co gamma irradiation over the dose range 0.1-100 kGy. The intensity of the EPR signal increases linearly in the range 0.1-35 kGy, the uncertainty budget for high doses being 3.3% at the 2σ confidence level. The rod form represents an excellent alternative dosimeter for high level dosimetry, of small uncertainty compared to powder form.

  1. Anticonvulsant properties of alpha, gamma, and alpha, gamma-substituted gamma-butyrolactones.

    PubMed

    Klunk, W E; Covey, D F; Ferrendelli, J A

    1982-09-01

    Derivatives of gamma-butyrolactone (GBL) substituted on the alpha- and/or gamma-positions were synthesized and tested for their effects on behavior in mice, on the electroencephalographs and blood pressure of paralyzed-ventilated guinea pigs, and on electrical activity of incubated hippocampal slices. Several compounds, including alpha-ethyl-alpha-methyl GBL (alpha-EMGBL), alpha, alpha-dimethyl GBL, alpha, gamma-diethyl-alpha, gamma-dimethyl GBL, and gamma-ethyl-gamma-methyl GBL, prevented seizures induced by pentylenetetrazol, beta-ethyl-beta-methyl-gamma-butyrolactone (beta-EMGBL), picrotoxin, or all three compounds in mice and guinea pigs but had no effect on seizures induced by maximal electroshock or bicuculline. Neither gamma-hydroxybutyrate (GHB) nor alpha-isopropylidine GBL had any anticonvulsant activity. The anticonvulsant alpha-substituted compounds had a potent hypotensive effect and antagonized the hypertensive effect of beta-EMGBL, alpha-EMGBL was tested in incubated hippocampal slices and was found to depress basal activity and antagonize excitation induced by beta-EMGBL. These results demonstrate that alpha-alkyl-substituted GBL and, to a lesser extent, gamma-substituted derivatives are anticonvulsant agents and that their effects are strikingly different from those of GHB or beta-alkyl-substituted GBLs, which are epileptogenic. Possibly beta- and alpha-substituted GBLs act at the same site as agonists and antagonists, respectively.

  2. 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

  3. Poster — Thur Eve — 25: Sensitivity to inhomogeneities for an in-vivo EPID dosimetry method

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

    Peca, Stefano; Brown, Derek; Department of Physics and Astronomy, University of Calgary, Calgary, AB

    2014-08-15

    Introduction: The electronic portal imaging device (EPID) has the potential to be used for in vivo dosimetry during radiotherapy as an additional dose delivery check. We recently proposed a simple method of using the EPID for 2D-IVD based on correlation ratios. In this work we have investigated the sensitivity of our EPID-IVD to inhomogeneities. Methods: We used slab phantoms that simulate water, bone, and lung, arranged in various geometries. To simulate body contours non-orthogonal to the field, we used a water wedge. CT data of these phantoms was imported into MATLAB, in conjunction with EPID images acquired during irradiation, tomore » calculate dose inside the phantom in isocenter plane. Each phantom was irradiated using a linear accelerator while images were acquired with the EPID (cine mode). Comparisons between EPID-calculated and TPS dose maps were: pixel-by-pixel dose difference, and 3%,3mm gamma evaluation. Results: In the homogeneous case, CAX dose difference was <1%, and 3%,3mm gamma analysis yielded 99% of points with gamma<1. For the inhomogeneous phantoms, agreement decreased with increasing inhomogeneity reaching up to 10% CAX dose difference with 10cm of lung. Results from the water wedge phantom suggest that the EPID-calculated dose can account for surface irregularities of approximately ±3cm. Conclusions: The EPID-based IVD investigated has limitations in the presence of large inhomogeneities. Nonetheless, CAX doses never differed by >15% from the TPS. This suggests that this EPID-IVD is capable of detecting gross dose delivery errors even in the presence of inhomogeneities, supporting its utility as an additional patient safety device.« less

  4. 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

  5. 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.

  6. 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.

  7. Evaluation of a lithium formate EPR dosimetry system for dose measurements around {sup 192}Ir brachytherapy sources

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

    Antonovic, Laura; Gustafsson, Haakan; Alm Carlsson, Gudrun

    2009-06-15

    A dosimetry system using lithium formate monohydrate (HCO{sub 2}Li{center_dot}H{sub 2}O) as detector material and electron paramagnetic resonance (EPR) spectroscopy for readout has been used to measure absorbed dose distributions around clinical {sup 192}Ir sources. Cylindrical tablets with diameter of 4.5 mm, height of 4.8 mm, and density of 1.26 g/cm{sup 3} were manufactured. Homogeneity test and calibration of the dosimeters were performed in a 6 MV photon beam. {sup 192}Ir irradiations were performed in a PMMA phantom using two different source models, the GammaMed Plus HDR and the microSelectron PDR-v1 model. Measured absorbed doses to water in the PMMA phantommore » were converted to the corresponding absorbed doses to water in water phantoms of dimensions used by the treatment planning systems (TPSs) using correction factors explicitly derived for this experiment. Experimentally determined absorbed doses agreed with the absorbed doses to water calculated by the TPS to within {+-}2.9%. Relative standard uncertainties in the experimentally determined absorbed doses were estimated to be within the range of 1.7%-1.3% depending on the radial distance from the source, the type of source (HDR or PDR), and the particular absorbed doses used. This work shows that a lithium formate dosimetry system is well suited for measurements of absorbed dose to water around clinical HDR and PDR {sup 192}Ir sources. Being less energy dependent than the commonly used thermoluminescent lithium fluoride (LiF) dosimeters, lithium formate monohydrate dosimeters are well suited to measure absorbed doses in situations where the energy dependence cannot easily be accounted for such as in multiple-source irradiations to verify treatment plans. Their wide dynamic range and linear dose response over the dose interval of 0.2-1000 Gy make them suitable for measurements on sources of the strengths used in clinical applications. The dosimeter size needs, however, to be reduced for application

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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...

  14. 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.

  15. 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

  16. Interpretation of Gamma Index for Quality Assurance of Simultaneously Integrated Boost (SIB) IMRT Plans for Head and Neck Carcinoma

    NASA Astrophysics Data System (ADS)

    Atiq, Maria; Atiq, Atia; Iqbal, Khalid; Shamsi, Quratul ain; Andleeb, Farah; Buzdar, Saeed Ahmad

    2017-12-01

    Objective: The Gamma Index is prerequisite to estimate point-by-point difference between measured and calculated dose distribution in terms of both Distance to Agreement (DTA) and Dose Difference (DD). This study aims to inquire what percentage of pixels passing a certain criteria assure a good quality plan and suggest gamma index as efficient mechanism for dose verification of Simultaneous Integrated Boost Intensity Modulated Radiotherapy plans. Method: In this study, dose was calculated for 14 head and neck patients and IMRT Quality Assurance was performed with portal dosimetry using the Eclipse treatment planning system. Eclipse software has a Gamma analysis function to compare measured and calculated dose distribution. Plans of this study were deemed acceptable when passing rate was 95% using tolerance for Distance to agreement (DTA) as 3mm and Dose Difference (DD) as 5%. Result and Conclusion: Thirteen cases pass tolerance criteria of 95% set by our institution. Confidence Limit for DD is 9.3% and for gamma criteria our local CL came out to be 2.0% (i.e., 98.0% passing). Lack of correlation was found between DD and γ passing rate with R2 of 0.0509. Our findings underline the importance of gamma analysis method to predict the quality of dose calculation. Passing rate of 95% is achieved in 93% of cases which is adequate level of accuracy for analyzed plans thus assuring the robustness of SIB IMRT treatment technique. This study can be extended to investigate gamma criteria of 5%/3mm for different tumor localities and to explore confidence limit on target volumes of small extent and simple geometry.

  17. 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

  18. 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

  19. 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.

  20. TH-CD-BRA-11: Implementation and Evaluation of a New 3D Dosimetry Protocol for Validating MRI Guided Radiation Therapy Treatments

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

    Mein, S; Rankine, L; Department of Radiation Oncology, Washington University School of Medicine

    Purpose: To develop, evaluate and apply a novel high-resolution 3D remote dosimetry protocol for validation of MRI guided radiation therapy treatments (MRIdian by ViewRay™). We demonstrate the first application of the protocol (including two small but required new correction terms) utilizing radiochromic 3D plastic PRESAGE™ with optical-CT readout. Methods: A detailed study of PRESAGE™ dosimeters (2kg) was conducted to investigate the temporal and spatial stability of radiation induced optical density change (ΔOD) over 8 days. Temporal stability was investigated on 3 dosimeters irradiated with four equally-spaced square 6MV fields delivering doses between 10cGy and 300cGy. Doses were imaged (read-out) bymore » optical-CT at multiple intervals. Spatial stability of ΔOD response was investigated on 3 other dosimeters irradiated uniformly with 15MV extended-SSD fields with doses of 15cGy, 30cGy and 60cGy. Temporal and spatial (radial) changes were investigated using CERR and MATLAB’s Curve Fitting Tool-box. A protocol was developed to extrapolate measured ΔOD readings at t=48hr (the typical shipment time in remote dosimetry) to time t=1hr. Results: All dosimeters were observed to gradually darken with time (<5% per day). Consistent intra-batch sensitivity (0.0930±0.002 ΔOD/cm/Gy) and linearity (R2=0.9996) was observed at t=1hr. A small radial effect (<3%) was observed, attributed to curing thermodynamics during manufacture. The refined remote dosimetry protocol (including polynomial correction terms for temporal and spatial effects, CT and CR) was then applied to independent dosimeters irradiated with MR-IGRT treatments. Excellent line profile agreement and 3D-gamma results for 3%/3mm, 10% threshold were observed, with an average passing rate 96.5%± 3.43%. Conclusion: A novel 3D remote dosimetry protocol is presented capable of validation of advanced radiation treatments (including MR-IGRT). The protocol uses 2kg radiochromic plastic dosimeters read

  1. Evaluation of the radiobiological gamma index with motion interplay in tangential IMRT breast treatment

    PubMed Central

    Sumida, Iori; Yamaguchi, Hajime; Das, Indra J.; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yamada, Yuji; Tamari, Kiesuke; Suzuki, Osamu; Seo, Yuji; Isohashi, Fumiaki; Yoshioka, Yasuo; Ogawa, Kazuhiko

    2016-01-01

    The purpose of this study was to evaluate the impact of the motion interplay effect in early-stage left-sided breast cancer intensity-modulated radiation therapy (IMRT), incorporating the radiobiological gamma index (RGI). The IMRT dosimetry for various breathing amplitudes and cycles was investigated in 10 patients. The predicted dose was calculated using the convolution of segmented measured doses. The physical gamma index (PGI) of the planning target volume (PTV) and the organs at risk (OAR) was calculated by comparing the original with the predicted dose distributions. The RGI was calculated from the PGI using the tumor control probability (TCP) and the normal tissue complication probability (NTCP). The predicted mean dose and the generalized equivalent uniform dose (gEUD) to the target with various breathing amplitudes were lower than the original dose (P < 0.01). The predicted mean dose and gEUD to the OARs with motion were higher than for the original dose to the OARs (P < 0.01). However, the predicted data did not differ significantly between the various breathing cycles for either the PTV or the OARs. The mean RGI gamma passing rate for the PTV was higher than that for the PGI (P < 0.01), and for OARs, the RGI values were higher than those for the PGI (P < 0.01). The gamma passing rates of the RGI for the target and the OARs other than the contralateral lung differed significantly from those of the PGI under organ motion. Provided an NTCP value <0.05 is considered acceptable, it may be possible, by taking breathing motion into consideration, to escalate the dose to achieve the PTV coverage without compromising the TCP. PMID:27534793

  2. Three-dimensional radiochromic film dosimetry for volumetric modulated arc therapy using a spiral water phantom

    PubMed Central

    Tanooka, Masao; Doi, Hiroshi; Miura, Hideharu; Inoue, Hiroyuki; Niwa, Yasue; Takada, Yasuhiro; Fujiwara, Masayuki; Sakai, Toshiyuki; Sakamoto, Kiyoshi; Kamikonya, Norihiko; Hirota, Shozo

    2013-01-01

    We validated 3D radiochromic film dosimetry for volumetric modulated arc therapy (VMAT) using a newly developed spiral water phantom. The phantom consists of a main body and an insert box, each of which has an acrylic wall thickness of 3 mm and is filled with water. The insert box includes a spiral film box used for dose-distribution measurement, and a film holder for positioning a radiochromic film. The film holder has two parallel walls whose facing inner surfaces are equipped with spiral grooves in a mirrored configuration. The film is inserted into the spiral grooves by its side edges and runs along them to be positioned on a spiral plane. Dose calculation was performed by applying clinical VMAT plans to the spiral water phantom using a commercial Monte Carlo-based treatment-planning system, Monaco, whereas dose was measured by delivering the VMAT beams to the phantom. The calculated dose distributions were resampled on the spiral plane, and the dose distributions recorded on the film were scanned. Comparisons between the calculated and measured dose distributions yielded an average gamma-index pass rate of 87.0% (range, 91.2–84.6%) in nine prostate VMAT plans under 3 mm/3% criteria with a dose-calculation grid size of 2 mm. The pass rates were increased beyond 90% (average, 91.1%; range, 90.1–92.0%) when the dose-calculation grid size was decreased to 1 mm. We have confirmed that 3D radiochromic film dosimetry using the spiral water phantom is a simple and cost-effective approach to VMAT dose verification. PMID:23685667

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. SU-C-201-06: Utility of Quantitative 3D SPECT/CT Imaging in Patient Specific Internal Dosimetry of 153-Samarium with GATE Monte Carlo Package

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

    Fallahpoor, M; Abbasi, M; Sen, A

    Purpose: Patient-specific 3-dimensional (3D) internal dosimetry in targeted radionuclide therapy is essential for efficient treatment. Two major steps to achieve reliable results are: 1) generating quantitative 3D images of radionuclide distribution and attenuation coefficients and 2) using a reliable method for dose calculation based on activity and attenuation map. In this research, internal dosimetry for 153-Samarium (153-Sm) was done by SPECT-CT images coupled GATE Monte Carlo package for internal dosimetry. Methods: A 50 years old woman with bone metastases from breast cancer was prescribed 153-Sm treatment (Gamma: 103keV and beta: 0.81MeV). A SPECT/CT scan was performed with the Siemens Simbia-Tmore » scanner. SPECT and CT images were registered using default registration software. SPECT quantification was achieved by compensating for all image degrading factors including body attenuation, Compton scattering and collimator-detector response (CDR). Triple energy window method was used to estimate and eliminate the scattered photons. Iterative ordered-subsets expectation maximization (OSEM) with correction for attenuation and distance-dependent CDR was used for image reconstruction. Bilinear energy mapping is used to convert Hounsfield units in CT image to attenuation map. Organ borders were defined by the itk-SNAP toolkit segmentation on CT image. GATE was then used for internal dose calculation. The Specific Absorbed Fractions (SAFs) and S-values were reported as MIRD schema. Results: The results showed that the largest SAFs and S-values are in osseous organs as expected. S-value for lung is the highest after spine that can be important in 153-Sm therapy. Conclusion: We presented the utility of SPECT-CT images and Monte Carlo for patient-specific dosimetry as a reliable and accurate method. It has several advantages over template-based methods or simplified dose estimation methods. With advent of high speed computers, Monte Carlo can be used for treatment

  10. 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

  11. 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.

  12. Quantifying the performance of in vivo portal dosimetry in detecting four types of treatment parameter variations

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

    Bojechko, C.; Ford, E. C., E-mail: eford@uw.edu

    Purpose: To quantify the ability of electronic portal imaging device (EPID) dosimetry used during treatment (in vivo) in detecting variations that can occur in the course of patient treatment. Methods: Images of transmitted radiation from in vivo EPID measurements were converted to a 2D planar dose at isocenter and compared to the treatment planning dose using a prototype software system. Using the treatment planning system (TPS), four different types of variability were modeled: overall dose scaling, shifting the positions of the multileaf collimator (MLC) leaves, shifting of the patient position, and changes in the patient body contour. The gamma passmore » rate was calculated for the modified and unmodified plans and used to construct a receiver operator characteristic (ROC) curve to assess the detectability of the different parameter variations. The detectability is given by the area under the ROC curve (AUC). The TPS was also used to calculate the impact of the variations on the target dose–volume histogram. Results: Nine intensity modulation radiation therapy plans were measured for four different anatomical sites consisting of 70 separate fields. Results show that in vivo EPID dosimetry was most sensitive to variations in the machine output, AUC = 0.70 − 0.94, changes in patient body habitus, AUC = 0.67 − 0.88, and systematic shifts in the MLC bank positions, AUC = 0.59 − 0.82. These deviations are expected to have a relatively small clinical impact [planning target volume (PTV) D{sub 99} change <7%]. Larger variations have even higher detectability. Displacements in the patient’s position and random variations in MLC leaf positions were not readily detectable, AUC < 0.64. The D{sub 99} of the PTV changed by up to 57% for the patient position shifts considered here. Conclusions: In vivo EPID dosimetry is able to detect relatively small variations in overall dose, systematic shifts of the MLC’s, and changes in the patient habitus. Shifts

  13. 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.

  14. 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.

  15. Study of gamma ray energy absorption and exposure buildup factors for ferrites by geometric progression fitting method

    NASA Astrophysics Data System (ADS)

    Raut, S. D.; Awasarmol, V. V.; Shaikh, S. F.; Ghule, B. G.; Ekar, S. U.; Mane, R. S.; Pawar, P. P.

    2018-04-01

    The gamma ray energy absorption and exposure buildup factors (EABF and EBF) were calculated for ferrites such as cobalt ferrite (CoFe2O4), zinc ferrite (ZnFe2O4), nickel ferrite (NiFe2O4) and magnesium ferrite (MgFe2O4) using five parametric geometric progression (G-P fitting) formula in the energy range 0.015-15.00 MeV up to the penetration depth 40 mean free path (mfp). The obtained data of absorption and exposure buildup factors have been studied as a function of incident photon energy and penetration depth. The obtained EABF and EBF data are useful for radiation dosimetry and radiation therapy.

  16. 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.

  17. gamma-Hexachlorocyclohexane (gamma-HCH)

    Integrated Risk Information System (IRIS)

    gamma - Hexachlorocyclohexane ( gamma - HCH ) ; CASRN 58 - 89 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asse

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Correcting lateral response artifacts from flatbed scanners for radiochromic film dosimetry

    PubMed Central

    Lewis, David; Chan, Maria F.

    2015-01-01

    lateral position response artifact. To validate this method, corrections were applied to several films that were exposed to 15 × 15cm2 open fields and large IMRT and VMAT fields and scanned at the extreme edges of the scan window in addition to the central location. Calibration and response data were used to generate dose maps and perform gamma analysis using single- or triple-channel dosimetry with FilmQAPro 2014 software. Results: The authors’ study found that calibration curves at the different lateral positions could be correlated by a simple two-point rescaling using the response for unexposed film as well as the response of film exposed at high doses between 800 and 1600 cGy. The coefficients AL,X and BL,X for each color channel X were found to be independent of dose at each lateral location L. This made it possible to apply the relationship Response(C, D, X) = AL,X + BL,X⋅Response(L, D, X), to the raw film responses, permitting correction of the response values at any lateral position to an equivalent response, as if that part of the film was located at the center of the scanner. This correction method was validated for several films exposed to open as well as large IMRT and VMAT fields. Conclusions: The work reported elaborates on the process using the correction procedures to eliminate the lateral response artifact and demonstrates improvements in the accuracy of radiochromic film dosimetry for the radiation therapy quality assurance applications. PMID:25563282

  5. One dimensional spatial resolution optimization on a hybrid low field MRI-gamma detector

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

    Agulles-Pedrós, L., E-mail: lagullesp@unal.edu.co; Abril, A., E-mail: ajabrilf@unal.edu.co

    Hybrid systems like Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) and MRI/gamma camera, offer advantages combining the resolution and contrast capability of MRI with the better contrast and functional information of nuclear medicine techniques. However, the radiation detectors are expensive and need an electronic set-up, which can interfere with the MRI acquisition process or viceversa. In order to improve these drawbacks, in this work it is presented the design of a low field NMR system made up of permanent magnets compatible with a gamma radiation detector based on gel dosimetry. The design is performed using the software FEMM for estimation ofmore » the magnetic field, and GEANT4 for the physical process involved in radiation detection and effect of magnetic field. The homogeneity in magnetic field is achieved with an array of NbFeB magnets in a linear configuration with a separation between the magnets, minimizing the effect of Compton back scattering compared with a no-spacing linear configuration. The final magnetic field in the homogeneous zone is ca. 100 mT. In this hybrid proposal, although the gel detector do not have spatial resolution per se, it is possible to obtain a dose profile (1D image) as a function of the position by using a collimator array. As a result, the gamma detector system described allows a complete integrated radiation detector within the low field NMR (lfNMR) system. Finally we present the better configuration for the hybrid system considering the collimator parameters such as height, thickness and distance.« less

  6. Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

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

    Massaro, F.; D'Abrusco, R.; Tosti, G.

    2012-04-02

    One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified {gamma}-ray sources (UGSs). Despite the large improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one third of the Fermi-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer (WISE) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Basedmore » on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated to the UGS sample of the second Fermi {gamma}-ray catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to {gamma}-ray sources in the 2FGL catalog.« less

  7. UNIDENTIFIED {gamma}-RAY SOURCES: HUNTING {gamma}-RAY BLAZARS

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

    Massaro, F.; Ajello, M.; D'Abrusco, R.

    2012-06-10

    One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of unidentified {gamma}-ray sources (UGSs). Despite the major improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one-third of the Fermi-detected objects are still not associated with low-energy counterparts. Recently, using the Wide-field Infrared Survey Explorer survey, we discovered that blazars, the rarest class of active galactic nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, wemore » designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated with the UGS sample of the second Fermi {gamma}-ray LAT catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart to each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated with {gamma}-ray sources in the 2FGL catalog.« less

  8. 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

  9. 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

  10. Use of the GEANT4 Monte Carlo to determine three-dimensional dose factors for radionuclide dosimetry

    NASA Astrophysics Data System (ADS)

    Amato, Ernesto; Italiano, Antonio; Minutoli, Fabio; Baldari, Sergio

    2013-04-01

    The voxel-level dosimetry is the most simple and common approach to internal dosimetry of nonuniform distributions of activity within the human body. Aim of this work was to obtain the dose "S" factors (mGy/MBqs) at the voxel level for eight beta and beta-gamma emitting radionuclides commonly used in nuclear medicine diagnostic and therapeutic procedures. We developed a Monte Carlo simulation in GEANT4 of a region of soft tissue as defined by the ICRP, divided into 11×11×11 cubic voxels, 3 mm in side. The simulation used the parameterizations of the electromagnetic interaction optimized for low energy (EEDL, EPDL). The decay of each radionuclide (32P, 90Y, 99mTc, 177Lu, 131I, 153Sm, 186Re, 188Re) were simulated homogeneously distributed within the central voxel (0,0,0), and the energy deposited in the surrounding voxels was mediated on the 8 octants of the three dimensional space, for reasons of symmetry. The results obtained were compared with those available in the literature. While the iodine deviations remain within 16%, for phosphorus, a pure beta emitter, the agreement is very good for self-dose (0,0,0) and good for the dose to first neighbors, while differences are observed ranging from -60% to +100% for voxels far distant from the source. The existence of significant differences in the percentage calculation of the voxel S factors, especially for pure beta emitters such as 32P or 90Y, has already been highlighted by other authors. These data can usefully extend the dosimetric approach based on the voxel to other radionuclides not covered in the available literature.

  11. The ENEA criticality accident dosimetry system: a contribution to the 2002 international intercomparison at the SILENE reactor.

    PubMed

    Gualdrini, G; Bedogni, R; Fantuzzi, E; Mariotti, F

    2004-01-01

    The present paper summarises the activity carried out at the ENEA Radiation Protection Institute for updating the methodologies employed for the evaluation of the neutron and photon dose to the exposed workers in case of a criticality accident, in the framework of the 'International Intercomparison of Criticality Accident Dosimetry Systems' (Silène reactor, IRSN-CEA-Valduc June 2002). The evaluation of the neutron spectra and the neutron dosimetric quantities relies on activation detectors and on unfolding algorithms. Thermoluminescent detectors are employed for the gamma dose measurement. The work is aimed at accurately characterising the measurement system and, at the same time, testing the algorithms. Useful spectral information were included, based on Monte Carlo simulations, to take into account the potential accident scenarios of practical interest. All along this exercise intercomparison a particular attention was devoted to the 'traceability' of all the experimental and computational parameters and therefore, aimed at an easy treatment by the user.

  12. SU-E-T-364: 6X FFF and 10X FFF Portal Dosimetry Output Factor Verification: Application for SRS/SBRT

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

    Gulam, M; Bellon, M; Gopal, A

    2014-06-01

    Purpose: To enhance portal dosimetry of high dose rate SRS/SBRT plan verifications with extensive imager measurement of output factors (OF). Methods: Electronic portal image dosimetry (EPID), implemented on the Varian Edge allows for acquisition of its two energies: 6X FFF and 10 FFF (1400 and 2400 MU/min, respectively) at source to imager distance (SID) =100cm without imager saturation. Square and rectangular aSi OF following EPID calibration were obtained. Data taken was similar to that obtained during beam commissioning (of almost all field sizes from 1×1 to 15×15 and 20×20 cm{sup 2}, [Trilogy] and [Edge], respectively) to construct a table usingmore » the OF tool for use in the Portal Dosimetry Prediction Algorithm (PDIP v11). The Trilogy 6x SRS 1000 MU/min EPID data were taken at 140 SID. The large number of OF were obtained for comparison to that obtained with diode detectors and ion chambers (cc13 for >3×3 field size). As Edge PDIP verification is currently ongoing, EPID measurements of three SRS/SBRT plans for the Trilogy were taken and compared to results obtained prior to these measurements. Results: The relative difference output factors of field sizes 2×2 and higher compared to commissioning data were (mean+/-SD, [range]): Edge 6X (−1.9+/−2.9%, [−5.9%,3.1%]), Edge 10X (−0.7+/−1.2%, [− 3.3%,0.8%] and Trilogy (0.03+/−0.5%, [−1.4%,1.1%]) with EPID over predicting. The results for the 140 SID showed excellent agreement throughout except at the 1×1 to 1×15 and 15×1 field sizes where differences were: −10.6%, −6.0% and −5.8%. The differences were also most pronounced for the 1×1 at 100 SID. They were −7.4% and −11.5% for 6X and 10X, respectively. The Gamma (3%, 1mm) for three clinical plans improved by 8.7+/−1.8%. Conclusion: Results indicate that imager output factor measurements at any SID of high dose rate SRS/SBRT are quite reliable for portal dosimetry plan verification except for the smallest fields. This work was

  13. Growth kinetics of gamma-prime precipitates in a directionally solidified eutectic, gamma/gamma-prime-delta

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    A directionally solidified eutectic alloy (DSEA), of those viewed as potential candidates for the next generation of aircraft gas turbine blade materials, is studied for the gamma-prime growth kinetics, in the system Ni-Nb-Cr-Al, specifically: Ni-20 w/o Nb-6 w/o Cr-2.5 w/o Al gamma/gamma-prime-delta DSEA. Heat treatment, polishing and etching, and preparation for electron micrography are described, and the size distribution of gamma-prime phase following various anneals is plotted, along with gamma-prime growth kinetics in this specific DSEA, and the cube of gamma-prime particle size vs anneal time. Activation energies and coarsening kinetics are studied.

  14. The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

    2015-05-01

    Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

  15. 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.

  16. A multi-institutional dosimetry audit of rotational intensity-modulated radiotherapy.

    PubMed

    Clark, Catharine H; Hussein, Mohammad; Tsang, Yatman; Thomas, Russell; Wilkinson, Dean; Bass, Graham; Snaith, Julia; Gouldstone, Clare; Bolton, Steve; Nutbrown, Rebecca; Venables, Karen; Nisbet, Andrew

    2014-11-01

    Rotational IMRT (VMAT and Tomotherapy) has now been implemented in many radiotherapy centres. An audit to verify treatment planning system modelling and treatment delivery has been undertaken to ensure accurate clinical implementation. 34 institutions with 43 treatment delivery systems took part in the audit. A virtual phantom planning exercise (3DTPS test) and a clinical trial planning exercise were planned and independently measured in each institution using a phantom and array combination. Point dose differences and global gamma index (γ) were calculated in regions corresponding to PTVs and OARs. Point dose differences gave a mean (±sd) of 0.1±2.6% and 0.2±2.0% for the 3DTPS test and clinical trial plans, respectively. 34/43 planning and delivery combinations achieved all measured planes with >95% pixels passing γ<1 at 3%/3mm and rose to 42/43 for clinical trial plans. A statistically significant difference in γ pass rates (p<0.01) was seen between planning systems where rotational IMRT modelling had been designed for the manufacturer's own treatment delivery system and those designed independently of rotational IMRT delivery. A dosimetry audit of rotational radiotherapy has shown that TPS modelling and delivery for rotational IMRT can achieve high accuracy of plan delivery. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. Synthesis, characteristics and thermoluminescent dosimetry features of γ-irradiated Ce doped CaF2 nanophosphor.

    PubMed

    Zahedifar, M; Sadeghi, E; Mozdianfard, M R; Habibi, E

    2013-08-01

    Nanoparticles of cerium doped calcium fluoride (CaF2:Ce) were synthesized for the first time using the hydrothermal method. The formation of nanostructures was confirmed by X-ray diffraction (XRD) patterns, indicating cubic lattice structure for the particles produced. Their shape and size were observed by scanning electron microscopy (SEM). Thermoluminescence characteristics were studied by having the samples irradiated by gamma rays of (60)Co source. The optimum thermal treatment of 400 °C for 30 min was found for the produced nanoparticles. The Tm-Tstop and computerized glow curve deconvolution (CGCD) methods, used to determine the number of component glow peaks and kinetic parameters, indicated seven overlapping glow peaks on the TL glow curve at approximately 394, 411, 425, 445, 556, 594 and 632 K. A linear dose response of up to 2000 Gy, was observed for the prepared nanoparticles. Maximum TL sensitivity was found at 0.4 mol% of Ce impurity. Other TL dosimetry features, including reusability and fading, were also presented and discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Very high-energy gamma rays from gamma-ray bursts.

    PubMed

    Chadwick, Paula M

    2007-05-15

    Very high-energy (VHE) gamma-ray astronomy has undergone a transformation in the last few years, with telescopes of unprecedented sensitivity having greatly expanded the source catalogue. Such progress makes the detection of a gamma-ray burst at the highest energies much more likely than previously. This paper describes the facilities currently operating and their chances for detecting gamma-ray bursts, and reviews predictions for VHE gamma-ray emission from gamma-ray bursts. Results to date are summarized.

  6. 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.

  7. 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

  8. An external dosimetry audit programme to credential static and rotational IMRT delivery for clinical trials quality assurance.

    PubMed

    Eaton, David J; Tyler, Justine; Backshall, Alex; Bernstein, David; Carver, Antony; Gasnier, Anne; Henderson, Julia; Lee, Jonathan; Patel, Rushil; Tsang, Yatman; Yang, Huiqi; Zotova, Rada; Wells, Emma

    2017-03-01

    External dosimetry audits give confidence in the safe and accurate delivery of radiotherapy. The RTTQA group have performed an on-site audit programme for trial recruiting centres, who have recently implemented static or rotational IMRT, and those with major changes to planning or delivery systems. Measurements of reference beam output were performed by the host centre, and by the auditor using independent equipment. Verification of clinical plans was performed using the ArcCheck helical diode array. A total of 54 measurement sessions were performed between May 2014 and June 2016 at 28 UK institutions, reflecting the different combinations of planning and delivery systems used at each institution. Average ratio of measured output between auditor and host was 1.002±0.006. Average point dose agreement for clinical plans was -0.3±1.8%. Average (and 95% lower confidence intervals) of gamma pass rates at 2%/2mm, 3%/2mm and 3%/3mm respectively were: 92% (80%), 96% (90%) and 98% (94%). Moderately significant differences were seen between fixed gantry angle and rotational IMRT, and between combination of planning systems and linac manufacturer, but not between anatomical treatment site or beam energy. An external audit programme has been implemented for universal and efficient credentialing of IMRT treatments in clinical trials. Good agreement was found between measured and expected doses, with few outliers, leading to a simple table of optimal and mandatory tolerances for approval of dosimetry audit results. Feedback was given to some centres leading to improved clinical practice. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

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

    Chen, Y; Lin, Y; Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan

    Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ({sup 6}LiF: Mg, Ti) and TLD-700 ({sup 7}LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure ismore » 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)« less

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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%.

  19. MO-DE-209-04: Radiation Dosimetry in Breast Tomosynthesis

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

    Sechopoulos, I.

    2016-06-15

    Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBTmore » shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Feasibility study of glass dosimeter postal dosimetry audit of high-energy radiotherapy photon beams.

    PubMed

    Mizuno, Hideyuki; Kanai, Tatsuaki; Kusano, Yohsuke; Ko, Susumu; Ono, Mari; Fukumura, Akifumi; Abe, Kyoko; Nishizawa, Kanae; Shimbo, Munefumi; Sakata, Suoh; Ishikura, Satoshi; Ikeda, Hiroshi

    2008-02-01

    The characteristics of a glass dosimeter were investigated for its potential use as a tool for postal dose audits. Reproducibility, energy dependence, field size and depth dependence were compared to those of a thermoluminescence dosimeter (TLD), which has been the major tool for postal dose audits worldwide. A glass dosimeter, GD-302M (Asahi Techno Glass Co.) and a TLD, TLD-100 chip (Harshaw Co.) were irradiated with gamma-rays from a (60)Co unit and X-rays from a medical linear accelerator (4, 6, 10 and 20 MV). The dosimetric characteristics of the glass dosimeter were almost equivalent to those of the TLD, in terms of utility for dosimetry under the reference condition, which is a 10 x 10 cm(2) field and 10 cm depth. Because of its reduced fading, compared to the TLD, and easy quality control with the ID number, the glass dosimeter proved to be a suitable tool for postal dose audits. Then, we conducted postal dose surveys of over 100 facilities and got good agreement, with a standard deviation of about 1.3%. Based on this study, postal dose audits throughout Japan will be carried out using a glass dosimeter.

  9. 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

  10. 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

  11. A simplified model of the source channel of the Leksell GammaKnife tested with PENELOPE.

    PubMed

    Al-Dweri, Feras M O; Lallena, Antonio M; Vilches, Manuel

    2004-06-21

    Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3 degrees with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, v, z = 236 mm) show strong correlations between rho = (x2 + y2)(1/2) and their polar angle theta, on one side, and between tan(-1)(y/x) and their azimuthal angle phi, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

  12. Micrometer-resolved film dosimetry using a microscope in microbeam radiation therapy

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

    Bartzsch, Stefan, E-mail: stefan.bartzsch@icr.ac.uk; Oelfke, Uwe; Lott, Johanna

    2015-07-15

    Purpose: Microbeam radiation therapy (MRT) is a still preclinical tumor therapy approach that uses arrays of a few tens of micrometer wide parallel beams separated by a few 100 μm. The production, measurement, and planning of such radiation fields are a challenge up to now. Here, the authors investigate the feasibility of radiochromic film dosimetry in combination with a microscopic readout as a tool to validate peak and valley doses in MRT, which is an important requirement for a future clinical application of the therapy. Methods: Gafchromic{sup ®} HD-810 and HD-V2 films are exposed to MRT fields at the biomedicalmore » beamline ID17 of the European Synchrotron Radiation Facility (ESRF) and are afterward scanned with a microscope. The measured dose is compared with Monte Carlo calculations. Image analysis tools and film handling protocols are developed that allow accurate and reproducible dosimetry. The performance of HD-810 and HD-V2 films is compared and a detailed analysis of the resolution, noise, and energy dependence is carried out. Measurement uncertainties are identified and analyzed. Results: The dose was measured with a resolution of 5 × 1000 μm{sup 2} and an accuracy of 5% in the peak and between 10% and 15% in the valley region. As main causes for dosimetry uncertainties, statistical noise, film inhomogeneities, and calibration errors were identified. Calibration errors strongly increase at low doses and exceeded 3% for doses below 50 and 70 Gy for HD-V2 and HD-810 films, respectively. While the grain size of both film types is approximately 2 μm, the statistical noise in HD-V2 is much higher than in HD-810 films. However, HD-810 films show a higher energy dependence at low photon energies. Conclusions: Both film types are appropriate for dosimetry in MRT and the microscope is superior to the microdensitometer used before at the ESRF with respect to resolution and reproducibility. However, a very careful analysis of the image data is required

  13. The MCART radiation physics core: the quest for radiation dosimetry standardization.

    PubMed

    Kazi, Abdul M; MacVittie, Thomas J; Lasio, Giovanni; Lu, Wei; Prado, Karl L

    2014-01-01

    Dose-related radiobiological research results can only be compared meaningfully when radiation dosimetry is standardized. To this purpose, the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Medical Countermeasures Against Radiological Threats (MCART) consortium recently created a Radiation Physics Core (RPC) as an entity to assume responsibility of standardizing radiation dosimetry practices among its member laboratories. The animal research activities in these laboratories use a variety of ionizing photon beams from several irradiators such as 250-320 kVp x-ray generators, Cs irradiators, Co teletherapy machines, and medical linear accelerators (LINACs). In addition to this variety of sources, these centers use a range of irradiation techniques and make use of different dose calculation schemes to conduct their experiments. An extremely important objective in these research activities is to obtain a Dose Response Relationship (DRR) appropriate to their respective organ-specific models of acute and delayed radiation effects. A clear and unambiguous definition of the DRR is essential for the development of medical countermeasures. It is imperative that these DRRs are transparent between centers. The MCART RPC has initiated the establishment of standard dosimetry practices among member centers and is introducing a Remote Dosimetry Monitoring Service (RDMS) to ascertain ongoing quality assurance. This paper will describe the initial activities of the MCART RPC toward implementing these standardization goals. It is appropriate to report a summary of initial activities with the intent of reporting the full implementation at a later date.

  14. [The application of non-annealing thermoluminescent dosimetry (TLD)].

    PubMed

    Wu, J M; Chen, C S; Lan, R H

    1993-06-01

    Conventional use of Thermoluminescence (TL) in radiation dosimetry is very time-consuming. It requires repeating the procedures of preheating and annealing. In an attempt to simplify these procedures, we conducted an experiment of non-annealing TL dosimetry. This article reports the experiment's results. We adopted Lithium Fluoride (LiF) chip (TLD-100) in polystyrene under the exposure of Co-60, and the result was taken by HAR-SHAW-4000 TL reading system. The TL response was analyzed, including linearity, reproducibility and fading test. Because non-annealing TL response was greatly influenced by residual electron, TLD calibration curves were separated into two parts: (1) high dose region (HDR, 50-1500 cGy); (2) low dose region (LDR, 0-50 cGy). When TL dosimeters were exposed to a single high does (about 500 cGy), the HDR could be reproduced within 3% and fit a good linearity. For LDR, we had to give up the tail of glow curve in the high temperature region. We could then get good linearity and reproducibility. Furthermore, fading of non-annealing was apparently larger than annealing. We could control the fading of non-annealing was apparently larger than annealing. We could control the fading influence within 1% by taking the TL reading one hour after exposure. On the other hand, a combination of photon and electron exposure was also performed by non-annealing TL dosimetry. The results were compatible with Co-60 exposure in the same system.

  15. Dosimetry applications in GATE Monte Carlo toolkit.

    PubMed

    Papadimitroulas, Panagiotis

    2017-09-01

    Monte Carlo (MC) simulations are a well-established method for studying physical processes in medical physics. The purpose of this review is to present GATE dosimetry applications on diagnostic and therapeutic simulated protocols. There is a significant need for accurate quantification of the absorbed dose in several specific applications such as preclinical and pediatric studies. GATE is an open-source MC toolkit for simulating imaging, radiotherapy (RT) and dosimetry applications in a user-friendly environment, which is well validated and widely accepted by the scientific community. In RT applications, during treatment planning, it is essential to accurately assess the deposited energy and the absorbed dose per tissue/organ of interest, as well as the local statistical uncertainty. Several types of realistic dosimetric applications are described including: molecular imaging, radio-immunotherapy, radiotherapy and brachytherapy. GATE has been efficiently used in several applications, such as Dose Point Kernels, S-values, Brachytherapy parameters, and has been compared against various MC codes which are considered as standard tools for decades. Furthermore, the presented studies show reliable modeling of particle beams when comparing experimental with simulated data. Examples of different dosimetric protocols are reported for individualized dosimetry and simulations combining imaging and therapy dose monitoring, with the use of modern computational phantoms. Personalization of medical protocols can be achieved by combining GATE MC simulations with anthropomorphic computational models and clinical anatomical data. This is a review study, covering several dosimetric applications of GATE, and the different tools used for modeling realistic clinical acquisitions with accurate dose assessment. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  16. MO-AB-206-02: Testing Gamma Cameras Based On TG177 WG Report

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

    Halama, J.

    2016-06-15

    This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT

  17. Gamma-sky.net: Portal to the gamma-ray sky

    NASA Astrophysics Data System (ADS)

    Voruganti, Arjun; Deil, Christoph; Donath, Axel; King, Johannes

    2017-01-01

    http://gamma-sky.net is a novel interactive website designed for exploring the gamma-ray sky. The Map View portion of the site is powered by the Aladin Lite sky atlas, providing a scalable survey image tesselated onto a three-dimensional sphere. The map allows for interactive pan and zoom navigation as well as search queries by sky position or object name. The default image overlay shows the gamma-ray sky observed by the Fermi-LAT gamma-ray space telescope. Other survey images (e.g. Planck microwave images in low/high frequency bands, ROSAT X-ray image) are available for comparison with the gamma-ray data. Sources from major gamma-ray source catalogs of interest (Fermi-LAT 2FHL, 3FGL and a TeV source catalog) are overlaid over the sky map as markers. Clicking on a given source shows basic information in a popup, and detailed pages for every source are available via the Catalog View component of the website, including information such as source classification, spectrum and light-curve plots, and literature references. We intend for gamma-sky.net to be applicable for both professional astronomers as well as the general public. The website started in early June 2016 and is being developed as an open-source, open data project on GitHub (https://github.com/gammapy/gamma-sky). We plan to extend it to display more gamma-ray and multi-wavelength data. Feedback and contributions are very welcome!

  18. 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

  19. Solid state TL detectors for in vivo dosimetry in brachytherapy.

    PubMed

    Gambarini, G; Borroni, M; Grisotto, S; Maucione, A; Cerrotta, A; Fallai, C; Carrara, M

    2012-12-01

    In vivo dosimetry provides information about the actual dose delivered to the patient treated with radiotherapy and can be adopted within a routinary treatment quality assurance protocol. Aim of this study was to evaluate the feasibility of performing in vivo rectal dosimetry by placing thermoluminescence detectors directly on the transrectal ultrasound probe adopted for on-line treatment planning of high dose rate brachytherapy boosts of prostate cancer patients. A suitable protocol for TLD calibration has been set up. In vivo measurements resulted to be in good agreement with the calculated doses, showing that the proposed method is feasible and returns accurate results. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. SU-F-T-445: Effect of Triaxial Cables and Microdetectors in Small Field Dosimetry

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

    Das, I; Andersen, A

    2016-06-15

    Purpose: Advances in radiation treatment especially with smaller fields used in SRS, Gamma knife, Tomotherapy, Cyberknife, and IMRT, require a high degree of precision especially with microdetectors for small field dosimetry (Das et al, Med Ph, 35, 206, 2008; Alfonso et al, Med Phys, 35, 5179, 2008). Due to small signal, the triaxial cable becomes critical in terms of signal to noise ratio (SNR) which is studied with microdetectors. Methods: Six high quality triaxial cables, 9.1 meters long from different manufacturers without any defects were acquired along with 5 most popular microdetectors (microdiamond, plastic scintillators, SRS-diode, edge-diode and pinpoint). Amore » dedicated electrometer was used for each combination except W1 which has its own supermax electrometer. A 6MV photon beam from Varian True beam with 100 MU at a 600 MU/min was used. Measurements were made at a depth of 5 cm in water phantom. Field sizes were varied from 0.5 cm to 10 cm square fields. Readings were taken with combination of cables and microdetectors. Results: Signal is dependent on the quality of the connectors, cables and types of microdetector. The readings varied from nC to pC depending on the type of microdetector. The net signal, S, (Sc-Sn), where Sc is signal with chamber and Sn is without chamber is a linear function of sensitive volume, v; (S = α+β•V), where α and β are constants. The standard deviation (SD) in 3 sets of reading with each combination of cable-detector was extremely low <0.02%. As expected the SD is higher in small fields (<3cm). Maximum estimated error was only ±0.2% in cables-detector combinations. Conclusion: The choice of cables has relatively small effect (±0.2%) with microdosimeter and should be accounted in overall error estimation in k value that is needed to convert ratio of reading to dose in small field dosimetry.« less

  1. PREFACE: 8th International Conference on 3D Radiation Dosimetry (IC3DDose)

    NASA Astrophysics Data System (ADS)

    Olsson, Lars E.; Bäck, S.; Ceberg, Sofie

    2015-01-01

    IC3DDose 2014, the 8th International Conference on 3D Radiation Dosimetry was held in Ystad, Sweden, from 4-7 September 2014. This 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 7th and last meeting was held in Sydney, Australia from 4-8 November 2012. It is worth remembering that the conference series started at the very beginning of the intensity modulated radiotherapy era and that the dosimeters being developed then were, to some extent, ahead of the clinical need of radiotherapy. However, since then the technical developments in radiation therapy have been dramatic, with dynamic treatments, including tracking, gating and volumetric modulated arc therapy, widely introduced in the clinic with the need for 3D dosimetry thus endless. This was also reflected by the contributions at the meeting in Ystad. Accordingly the scope of the meeting has also broadened to IC3DDOSE - I See Three-Dimensional Dose. A multitude of dosimetry techniques and radiation detectors are now represented, all with the common denominator: three-dimensional or 3D. Additionally, quality assurance (QA) procedures and other aspects of clinical dosimetry are represented. The implementation of new dosimetric techniques in radiotherapy is a process that needs every kind of caution, carefulness and thorough validation. Therefore, the clinical needs, reformulated as the aims for IC3DDOSE - I See Three-Dimensional Dose, are: • Enhance the quality and accuracy of radiation therapy treatments through improved clinical dosimetry. • Investigate and understand the dosimetric challenges of modern radiation treatment techniques. • Provide

  2. Thermoluminescence dosimetry and its applications in medicine--Part 2: History and applications.

    PubMed

    Kron, T

    1995-03-01

    Thermoluminescence dosimetry (TLD) has been available for dosimetry of ionising radiation for nearly 100 years. The variety of materials and their different physical forms allow the determination of different radiation qualities over a wide range of absorbed dose. This makes TL dosimeters useful in radiation protection where dose levels of microGy are monitored as well as in radiotherapy where doses up to several Gray are to be measured. The major advantages of TL detectors are their small physical size and that no cables or auxiliary equipment is required during the dose assessment. Therefore TLD is a good method for point dose measurements in phantoms as well as for in vivo dosimetry on patients during radiotherapy treatment. As an integrative dosimetric technique, it can be applied to personal dosimetry and it lends itself to the determination of dose distributions due to multiple or moving radiation sources (e.g. conformal and dynamic radiotherapy, computed tomography). In addition, TL dosimeters are easy to transport, and they can be mailed. This makes them well suited for intercomparison of doses delivered in different institutions. The present article aims at describing the various applications TLD has found in medicine by taking into consideration the physics and practice of TLD measurements which have been discussed in the first part of this review (Australas. Phys. Eng. Sci. Med. 17: 175-199, 1994).

  3. In vivo gamma-rays induced initial DNA damage and the effect of famotidine in mouse leukocytes as assayed by the alkaline comet assay.

    PubMed

    Mozdarani, Hossein; Nasirian, Borzo; Haeri, S Abolghasem

    2007-03-01

    Ionizing radiation induces a variety of lesions in DNA, each of which can be used as a bio-indicator for biological dosimetry or the study of the radioprotective effects of substances. To assess gamma ray-induced DNA damage in vivo in mouse leukocytes at various doses and the effect of famotidine, blood was collected from Balb/c male mice after irradiation with 4 Gy gamma-rays at different time intervals post-irradiation. To assess the response, mice were irradiated with doses of gamma-rays at 1 to 4 Grays. Famotidine was injected intra-peritoneally (i.p) at a dose of 5 mg/kg at various time intervals before irradiation. Four slides were prepared from each sample and alkaline comet assay was performed using standard protocols. Results obtained show that radiation significantly increases DNA damage in leukocytes in a dose dependent manner (p < 0.01) when using appropriate sampling time after irradiation, because increasing sampling time after irradiation resulted in a time dependent disappearance of DNA damage. Treatment with only 5 mg/kg famotidine before 4 Gy irradiation led to almost 50% reduction in DNA damage when compared with those animals which received radiation alone. The radioprotective capability of famotidine might be attributed to radical scavenging properties and an anti-oxidation mechanism.

  4. Experimental active and passive dosimetry systems for the NASA Skylab program

    NASA Technical Reports Server (NTRS)

    Schneider, M. F.; Janni, J. F.; Ainsworth, G. C.

    1972-01-01

    Active and passive dosimetry instrumentation to measure absorbed dose, charged particle spectra, and linear energy transfer spectra inside the command module and orbital workshop on the Skylab program were developed and tested. The active dosimetry system consists of one integral unit employing both a tissue equivalent ionization chamber and silicon solid state detectors. The instrument measures dose rates from 0.2 millirad/hour to 25 rads/hour, linear energy transfer spectra from 2.8 to 42.4 Kev/micron, and the proton and alpha particle energy spectra from 0.5 to 75 Mev. The active dosimeter is equipped with a portable radiation sensor for use in astronaut on-body and spacecraft shielding surveys during passage of the Skylab through significant space radiations. Data are transmitted in real time or are recorded by onboard spacecraft tape recorder for rapid evaluation of the radiation levels. The passive dosimetry systems consist of twelve (12) hard-mounted assemblies, each containing a variety of passive radiation sensors which are recoverable at the end of the mission for analysis.

  5. Gamma-ray and neutron dosimetry by EPR and AMS, using tooth enamel from atomic-bomb survivors: a mini review.

    PubMed

    Nakamura, Nori; Hirai, Yuko; Kodama, Yoshiaki

    2012-03-01

    The electron paramagnetic resonance (EPR, or electron spin resonance) method was used to measure CO₂⁻· radicals recorded in tooth enamel by exposure to atomic-bomb gamma rays. The EPR-estimated doses (i.e. ⁶⁰Co gamma-ray equivalent dose) were generally in good correlation with cytogenetic data of the same survivors, whereas plots of EPR-estimated dose or cytogenetically estimated dose against DS02 doses turned out to scatter more widely. Because those survivors whose EPR doses were higher (or lower) than DS02 doses tended to show also higher (or lower) responses for cytogenetic responses, the apparent variation appears primarily due to problems in individual DS02 doses rather than the measurement errors associated with the EPR or cytogenetic technique. A part of the enamel samples were also used for evaluation of neutron doses by measuring ⁴¹Ca/⁴⁰Ca ratios using the accelerator mass spectrometry technique. The results for the measured ratios were on average ~85 % of the calculated ratios by DS02 (but within the 95 % confidence bounds of the simulated results), which lends support to DS02-derived neutron doses to the survivors.

  6. Protocol for emergency EPR dosimetry in fingernails

    USDA-ARS?s Scientific Manuscript database

    There is an increased need for after-the fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effect...

  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

    Purpose: Estimation of the radiation dose to internal organs is essential for the assessment of radiation risks and benefits to patients undergoing diagnostic and therapeutic nuclear medicine procedures including PET. Respiratory motion induces notable internal organ displacement, which influences the absorbed dose for external exposure to radiation. However, to their knowledge, the effect of respiratory motion on internal radiation dosimetry has never been reported before. Methods: Thirteen computational models representing the adult male at different respiratory phases corresponding to the normal respiratory cycle were generated from the 4D dynamic XCAT phantom. Monte Carlo calculations were performed using the MCNP transportmore » code to estimate the specific absorbed fractions (SAFs) of monoenergetic photons/electrons, the S-values of common positron-emitting radionuclides (C-11, N-13, O-15, F-18, Cu-64, Ga-68, Rb-82, Y-86, and I-124), and the absorbed dose of {sup 18}F-fluorodeoxyglucose ({sup 18}F-FDG) in 28 target regions for both the static (average of dynamic frames) and dynamic phantoms. Results: The self-absorbed dose for most organs/tissues is only slightly influenced by respiratory motion. However, for the lung, the self-absorbed SAF is about 11.5% higher at the peak exhale phase than the peak inhale phase for photon energies above 50 keV. The cross-absorbed dose is obviously affected by respiratory motion for many combinations of source-target pairs. The cross-absorbed S-values for the heart contents irradiating the lung are about 7.5% higher in the peak exhale phase than the peak inhale phase for different positron-emitting radionuclides. For {sup 18}F-FDG, organ absorbed doses are less influenced by respiratory motion. Conclusions: Respiration-induced volume variations of the lungs and the repositioning of internal organs affect the self-absorbed dose of the lungs and cross-absorbed dose between organs in internal radiation dosimetry. The dynamic

  8. 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.

  9. A small-scale anatomical dosimetry model of the liver

    NASA Astrophysics Data System (ADS)

    Stenvall, Anna; Larsson, Erik; Strand, Sven-Erik; Jönsson, Bo-Anders

    2014-07-01

    Radionuclide therapy is a growing and promising approach for treating and prolonging the lives of patients with cancer. For therapies where high activities are administered, the liver can become a dose-limiting organ; often with a complex, non-uniform activity distribution and resulting non-uniform absorbed-dose distribution. This paper therefore presents a small-scale dosimetry model for various source-target combinations within the human liver microarchitecture. Using Monte Carlo simulations, Medical Internal Radiation Dose formalism-compatible specific absorbed fractions were calculated for monoenergetic electrons; photons; alpha particles; and 125I, 90Y, 211At, 99mTc, 111In, 177Lu, 131I and 18F. S values and the ratio of local absorbed dose to the whole-organ average absorbed dose was calculated, enabling a transformation of dosimetry calculations from macro- to microstructure level. For heterogeneous activity distributions, for example uptake in Kupffer cells of radionuclides emitting low-energy electrons (125I) or high-LET alpha particles (211At) the target absorbed dose for the part of the space of Disse, closest to the source, was more than eight- and five-fold the average absorbed dose to the liver, respectively. With the increasing interest in radionuclide therapy of the liver, the presented model is an applicable tool for small-scale liver dosimetry in order to study detailed dose-effect relationships in the liver.

  10. Thermoluminescence glow-curve characteristics of LiF phosphors at high doses of gamma radiation

    NASA Astrophysics Data System (ADS)

    Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

    2013-05-01

    High doses of ionising radiation are becoming increasingly common for radiation-processing applications of various medical, agricultural and polymer products using gamma and electron beams. The objective of this work was to study thermoluminescence (TL) glow-curve characteristics of commonly used commercial LiF TL phosphors at high doses of radiation with a view to use them in dosimetry of radiation-processing applications. The TL properties of TLD 100 and 700 phosphors, procured from the Thermo-Scientific (previously Harshaw) company, have been studied in the dose range of 1-60 kGy. The shift in glow peaks was observed in this dose range. Integral TL responses of TLD 100 and TLD 700 were found to decrease as a linear function of dose in the range of 5-50 kGy. The paper describes initial results related to the glow-curve characteristics of these phosphors.

  11. Resonance production in. gamma gamma. collisions

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

    Renard, F.M.

    1983-04-01

    The processes ..gamma gamma.. ..-->.. hadrons can be depicted as follows. One photon creates a q anti q pair which starts to evolve; the other photon can either (A) make its own q anti q pair and the (q anti q q anti q) system continue to evolve or (B) interact with the quarks of the first pair and lead to a modified (q anti q) system in interaction with C = +1 quantum numbers. A review of the recent theoretical activity concerning resonance production and related problems is given under the following headings: hadronic C = +1 spectroscopy (qmore » anti q, qq anti q anti q, q anti q g, gg, ggg bound states and mixing effects); exclusive ..gamma gamma.. processes (generalities, unitarized Born method, VDM and QCD); total cross section (soft and hard contributions); q/sup 2/ dependence of soft processes (soft/hard separation, 1/sup +- +/ resonances); and polarization effects. (WHK)« less

  12. 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

  13. A simplified model of the source channel of the Leksell GammaKnife® tested with PENELOPE

    NASA Astrophysics Data System (ADS)

    Al-Dweri, Feras M. O.; Lallena, Antonio M.; Vilches, Manuel

    2004-06-01

    Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife®. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3° with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, y, z = 236 mm) show strong correlations between rgr = (x2 + y2)1/2 and their polar angle thgr, on one side, and between tan-1(y/x) and their azimuthal angle phgr, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

  14. Activation of QA devices and phantom materials under clinical scanning proton beams—a gamma spectrometry study

    NASA Astrophysics Data System (ADS)

    Hanušová, Tereza; Johnová, Kamila; Navrátil, Matěj; Valenta, Jiří; Müller, Lutz

    2018-06-01

    Activation of detectors and phantoms used for commissioning and quality assurance of clinical proton beams may lead to radiation protection issues. Good understanding of the activation nuclide vectors involved is necessary to assess radiation risk for the personnel working with these devices on a daily basis or to fulfill legal requirements regarding transport of radioactive material and its release to the public. 11 devices and material samples were irradiated with a 220 MeV proton pencil beam (PBS, Proton Therapy Center, Prague). This study focuses on devices manufactured by IBA Dosimetry GmbH: MatriXX PT, PPC05, Stingray, Zebra, Lynx, a Blue Phantom rail and samples of RW3, PMMA, titanium, copper and carbon fibre plastic. Monitor units (MU) were monitored during delivery. Gamma spectrometry was then performed for each item using a HPGe detector, with a focus on longer lived gamma emitting radionuclides. Activities were quantified for all found isotopes and compared to relevant legal limits for exemption and clearance of radioactive objects. Activation was found to be significant after long irradiation sessions, as done during commissioning of a proton therapy room. Some of the investigated devices may also cumulate activity in time, depending on the scenario of periodic irradiation in routine clinical practice. However, the levels of activity and resulting beta/gamma doses are more comparable to internationally recommended concentration limits for exemption than to dose limits for radiation workers. Results of this study will help to determine nuclide inventories required by some legal authorities for radiation protection purposes.

  15. Activation of QA devices and phantom materials under clinical scanning proton beams-a gamma spectrometry study.

    PubMed

    Hanušová, Tereza; Johnová, Kamila; Navrátil, Matěj; Valenta, Jiří; Müller, Lutz

    2018-06-07

    Activation of detectors and phantoms used for commissioning and quality assurance of clinical proton beams may lead to radiation protection issues. Good understanding of the activation nuclide vectors involved is necessary to assess radiation risk for the personnel working with these devices on a daily basis or to fulfill legal requirements regarding transport of radioactive material and its release to the public. 11 devices and material samples were irradiated with a 220 MeV proton pencil beam (PBS, Proton Therapy Center, Prague). This study focuses on devices manufactured by IBA Dosimetry GmbH: MatriXX PT, PPC05, Stingray, Zebra, Lynx, a Blue Phantom rail and samples of RW3, PMMA, titanium, copper and carbon fibre plastic. Monitor units (MU) were monitored during delivery. Gamma spectrometry was then performed for each item using a HPGe detector, with a focus on longer lived gamma emitting radionuclides. Activities were quantified for all found isotopes and compared to relevant legal limits for exemption and clearance of radioactive objects. Activation was found to be significant after long irradiation sessions, as done during commissioning of a proton therapy room. Some of the investigated devices may also cumulate activity in time, depending on the scenario of periodic irradiation in routine clinical practice. However, the levels of activity and resulting beta/gamma doses are more comparable to internationally recommended concentration limits for exemption than to dose limits for radiation workers. Results of this study will help to determine nuclide inventories required by some legal authorities for radiation protection purposes.

  16. Commissioning a CT-compatible LDR tandem and ovoid applicator using Monte Carlo calculation and 3D dosimetry

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

    Adamson, Justus; Newton, Joseph; Yang Yun

    2012-07-15

    -Sign , and 10 Degree-Sign caused a 1%{+-} 0.1%, 1.7%{+-} 0.4%, and 2.6%{+-} 0.7% increase in rectal dose, respectively, with smaller effect to dose to Point A, bladder, sigmoid, and bowel. For 3D dosimetry, 90.6% of voxels had a 3D {gamma}-index (criteria = 0.1 cm, 3% local signal) below 1.0 when comparing measured and expected dose about the unshielded source. Dose transmission through the gold shielding at a radial distance of 1 cm was 85.9%{+-} 0.2%, 83.4%{+-} 0.7%, and 82.5%{+-} 2.2% for Monte Carlo, and measurement for left and right buckets, respectively. Dose transmission was lowest at oblique angles from the bucket with a minimum of 56.7%{+-} 0.8%, 65.6%{+-} 1.7%, and 57.5%{+-} 1.6%, respectively. For a clinical T and O plan, attenuation from the buckets leads to a decrease in average Point A dose of {approx}3.2% and decrease in D{sub 2cc} to bladder, rectum, bowel, and sigmoid of 5%, 18%, 6%, and 12%, respectively. Conclusions: Differences between dummy and afterloading bucket position in the ovoids is minor compared to effects from asymmetric ovoid shielding, for which rectal dose is most affected. 3D dosimetry can fulfill a novel role in verifying Monte Carlo calculations of complex dose distributions as are common about brachytherapy sources and applicators.« less

  17. Effect of contrast media on megavoltage photon beam dosimetry.

    PubMed

    Rankine, Ashley W; Lanzon, Peter J; Spry, Nigel A

    2008-01-01

    The purpose of this study was to quantify changes in photon beam dosimetry caused by using contrast media during computed tomography (CT) simulation and determine if the resulting changes are clinically significant. The effect of contrast on dosimetry was first examined for a single 6-MV photon beam incident on a plane phantom with a structure of varying electron densities (rho(e)) and thickness. Patient studies were then undertaken in which CT data sets were collected with and without contrast for 6 typical patients. Three patients received IV contrast (Optiray-240) only and 3 received IV plus oral (Gastrograffin) contrast. Each patient was planned using conformal multifield techniques in accordance with the department standards. Two methods were used to compare the effect of contrast on dosimetry for each patient. The phantom analysis showed that the change in dose at the isocenter for a single 10 x 10 cm2 6-MV photon beam traversing 10 cm of a contrast-enhanced structure with rho(e) 1.22 was 7.0% (1.22 was the highest average rho(e) observed in the patient data). As a result of using contrast, increases in rho(e) were observed in structures for the 6 patients studied. Consequently, when using contrast-enhanced CT data for multifield planning, increases in dose at the isocenter and in critical structures were observed up to 2.1% and 2.5%, respectively. Planning on contrast-enhanced CT images may result in an increase in dose of up to 2.1% at the isocenter, which would generally be regarded as clinically insignificant. If, however, a critical organ is in close proximity to the planning target volume (PTV) and is planned to receive its maximum allowable dose, planning on contrast-enhanced CT images may result in that organ receiving dose beyond the recommended tolerance. In these instances, pre-contrast CT data should be used for dosimetry.

  18. Evaluation of a Fluorochlorozirconate Glass-Ceramic Storage Phosphor Plate for Gamma-Ray Computed Radiography

    DOE PAGES

    Leonard, Russell L.; Gray, Sharon K.; Alvarez, Carlos J.; ...

    2015-05-21

    In this paper, a fluorochlorozirconate (FCZ) glass-ceramic containing orthorhombic barium chloride crystals doped with divalent europium was evaluated for use as a storage phosphor in gamma-ray imaging. X-ray diffraction and phosphorimetry of the glass-ceramic sample showed the presence of a significant amount of orthorhombic barium chloride crystals in the glass matrix. Transmission electron microscopy and scanning electron microscopy were used to identify crystal size, structure, and morphology. The size of the orthorhombic barium chloride crystals in the FCZ glass matrix was very large, ~0.5–0.7 μm, which can limit image resolution. The FCZ glass-ceramic sample was exposed to 1 MeV gammamore » rays to determine its photostimulated emission characteristics at high energies, which were found to be suitable for imaging applications. Test images were made at 2 MeV energies using gap and step wedge phantoms. Gaps as small as 101.6 μm in a 440 stainless steel phantom were imaged using the sample imaging plate. Analysis of an image created using a depleted uranium step wedge phantom showed that emission is proportional to incident energy at the sample and the estimated absorbed dose. Finally, the results showed that the sample imaging plate has potential for gamma-ray-computed radiography and dosimetry applications.« less

  19. Determination of small field synthetic single-crystal diamond detector correction factors for CyberKnife, Leksell Gamma Knife Perfexion and linear accelerator.

    PubMed

    Veselsky, T; Novotny, J; Pastykova, V; Koniarova, I

    2017-12-01

    The aim of this study was to determine small field correction factors for a synthetic single-crystal diamond detector (PTW microDiamond) for routine use in clinical dosimetric measurements. Correction factors following small field Alfonso formalism were calculated by comparison of PTW microDiamond measured ratio M Qclin fclin /M Qmsr fmsr with Monte Carlo (MC) based field output factors Ω Qclin,Qmsr fclin,fmsr determined using Dosimetry Diode E or with MC simulation itself. Diode measurements were used for the CyberKnife and Varian Clinac 2100C/D linear accelerator. PTW microDiamond correction factors for Leksell Gamma Knife (LGK) were derived using MC simulated reference values from the manufacturer. PTW microDiamond correction factors for CyberKnife field sizes 25-5 mm were mostly smaller than 1% (except for 2.9% for 5 mm Iris field and 1.4% for 7.5 mm fixed cone field). The correction of 0.1% and 2.0% for 8 mm and 4 mm collimators, respectively, needed to be applied to PTW microDiamond measurements for LGK Perfexion. Finally, PTW microDiamond M Qclin fclin /M Qmsr fmsr for the linear accelerator varied from MC corrected Dosimetry Diode data by less than 0.5% (except for 1 × 1 cm 2 field size with 1.3% deviation). Regarding low resulting correction factor values, the PTW microDiamond detector may be considered an almost ideal tool for relative small field dosimetry in a large variety of stereotactic and radiosurgery treatment devices. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  20. Correcting lateral response artifacts from flatbed scanners for radiochromic film dosimetry.

    PubMed

    Lewis, David; Chan, Maria F

    2015-01-01

    lateral position response artifact. To validate this method, corrections were applied to several films that were exposed to 15 × 15 cm(2) open fields and large IMRT and VMAT fields and scanned at the extreme edges of the scan window in addition to the central location. Calibration and response data were used to generate dose maps and perform gamma analysis using single- or triple-channel dosimetry with FilmQAPro 2014 software. The authors' study found that calibration curves at the different lateral positions could be correlated by a simple two-point rescaling using the response for unexposed film as well as the response of film exposed at high doses between 800 and 1600 cGy. The coefficients A(L,X) and BL,X for each color channel X were found to be independent of dose at each lateral location L. This made it possible to apply the relationship Response(C, D, X) = A(L,X) + B(L,X) ⋅ Response(L, D, X), to the raw film responses, permitting correction of the response values at any lateral position to an equivalent response, as if that part of the film was located at the center of the scanner. This correction method was validated for several films exposed to open as well as large IMRT and VMAT fields. The work reported elaborates on the process using the correction procedures to eliminate the lateral response artifact and demonstrates improvements in the accuracy of radiochromic film dosimetry for the radiation therapy quality assurance applications.

  1. Radiation resistance of elastomeric O-rings in mixed neutron and gamma fields: Testing methodology and experimental results

    NASA Astrophysics Data System (ADS)

    Zenoni, A.; Bignotti, F.; Donzella, A.; Donzella, G.; Ferrari, M.; Pandini, S.; Andrighetto, A.; Ballan, M.; Corradetti, S.; Manzolaro, M.; Monetti, A.; Rossignoli, M.; Scarpa, D.; Alloni, D.; Prata, M.; Salvini, A.; Zelaschi, F.

    2017-11-01

    Materials and components employed in the presence of intense neutron and gamma fields are expected to absorb high dose levels that may induce deep modifications of their physical and mechanical properties, possibly causing loss of their function. A protocol for irradiating elastomeric materials in reactor mixed neutron and gamma fields and for testing the evolution of their main mechanical and physical properties with absorbed dose has been developed. Four elastomeric compounds used for vacuum O-rings, one fluoroelastomer polymer (FPM) based and three ethylene propylene diene monomer rubber (EPDM) based, presently available on the market have been selected for the test. One EPDM is rated as radiation resistant in gamma fields, while the other elastomers are general purpose products. Particular care has been devoted to dosimetry calculations, since absorbed dose in neutron fields, unlike pure gamma fields, is strongly dependent on the material composition and, in particular, on the hydrogen content. The products have been tested up to about 2 MGy absorbed dose. The FPM based elastomer, in spite of its lower dose absorption in fast neutron fields, features the largest variations of properties, with a dramatic increase in stiffness and brittleness. Out of the three EPDM based compounds, one shows large and rapid changes in the main mechanical properties, whereas the other two feature more stable behaviors. The performance of the EPDM rated as radiation resistant in pure gamma fields does not appear significantly better than that of the standard product. The predictive capability of the accelerated irradiation tests performed as well as the applicable concepts of threshold of radiation damage is discussed in view of the use of the examined products in the selective production of exotic species facility, now under construction at the Legnaro National Laboratories of the Italian Istituto Nazionale di Fisica Nucleare. It results that a careful account of dose rate effects

  2. Radiation resistance of elastomeric O-rings in mixed neutron and gamma fields: Testing methodology and experimental results.

    PubMed

    Zenoni, A; Bignotti, F; Donzella, A; Donzella, G; Ferrari, M; Pandini, S; Andrighetto, A; Ballan, M; Corradetti, S; Manzolaro, M; Monetti, A; Rossignoli, M; Scarpa, D; Alloni, D; Prata, M; Salvini, A; Zelaschi, F

    2017-11-01

    Materials and components employed in the presence of intense neutron and gamma fields are expected to absorb high dose levels that may induce deep modifications of their physical and mechanical properties, possibly causing loss of their function. A protocol for irradiating elastomeric materials in reactor mixed neutron and gamma fields and for testing the evolution of their main mechanical and physical properties with absorbed dose has been developed. Four elastomeric compounds used for vacuum O-rings, one fluoroelastomer polymer (FPM) based and three ethylene propylene diene monomer rubber (EPDM) based, presently available on the market have been selected for the test. One EPDM is rated as radiation resistant in gamma fields, while the other elastomers are general purpose products. Particular care has been devoted to dosimetry calculations, since absorbed dose in neutron fields, unlike pure gamma fields, is strongly dependent on the material composition and, in particular, on the hydrogen content. The products have been tested up to about 2 MGy absorbed dose. The FPM based elastomer, in spite of its lower dose absorption in fast neutron fields, features the largest variations of properties, with a dramatic increase in stiffness and brittleness. Out of the three EPDM based compounds, one shows large and rapid changes in the main mechanical properties, whereas the other two feature more stable behaviors. The performance of the EPDM rated as radiation resistant in pure gamma fields does not appear significantly better than that of the standard product. The predictive capability of the accelerated irradiation tests performed as well as the applicable concepts of threshold of radiation damage is discussed in view of the use of the examined products in the selective production of exotic species facility, now under construction at the Legnaro National Laboratories of the Italian Istituto Nazionale di Fisica Nucleare. It results that a careful account of dose rate effects

  3. 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.

  4. 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.

  5. 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.

  6. On flattening filter‐free portal dosimetry

    PubMed Central

    Novais, Juan Castro; Molina López, María Yolanda; Maqueda, Sheila Ruiz

    2016-01-01

    Varian introduced (in 2010) the option of removing the flattening filter (FF) in their C‐Arm linacs for intensity‐modulated treatments. This mode, called flattening filter‐free (FFF), offers the advantage of a greater dose rate. Varian's “Portal Dosimetry” is an electronic portal imager device (EPID)‐based tool for IMRT verification. This tool lacks the capability of verifying flattening filter‐free (FFF) modes due to saturation and lack of an image prediction algorithm. (Note: the latest versions of this software and EPID correct these issues.) The objective of the present study is to research the feasibility of said verifications (with the older versions of the software and EPID). By placing the EPID at a greater distance, the images can be acquired without saturation, yielding a linearity similar to the flattened mode. For the image prediction, a method was optimized based on the clinically used algorithm (analytical anisotropic algorithm (AAA)) over a homogeneous phantom. The depth inside the phantom and its electronic density were tailored. An application was developed to allow the conversion of a dose plane (in DICOM format) to Varian's custom format for Portal Dosimetry. The proposed method was used for the verification of test and clinical fields for the three qualities used in our institution for IMRT: 6X, 6FFF and 10FFF. The method developed yielded a positive verification (more than 95% of the points pass a 2%/2 mm gamma) for both the clinical and test fields. This method was also capable of “predicting” static and wedged fields. A workflow for the verification of FFF fields was developed. This method relies on the clinical algorithm used for dose calculation and is able to verify the FFF modes, as well as being useful for machine quality assurance. The procedure described does not require new hardware. This method could be used as a verification of Varian's Portal Dose Image Prediction. PACS number(s): 87.53.Kn, 87.55.T‐, 87.56.bd

  7. 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

  8. Implementation of an intraoperative electron radiotherapy in vivo dosimetry program.

    PubMed

    López-Tarjuelo, Juan; Morillo-Macías, Virginia; Bouché-Babiloni, Ana; Boldó-Roda, Enrique; Lozoya-Albacar, Rafael; Ferrer-Albiach, Carlos

    2016-03-15

    Intraoperative electron radiotherapy (IOERT) is a highly selective radiotherapy technique which aims to treat restricted anatomic volumes during oncological surgery and is now the subject of intense re-evaluation. In vivo dosimetry has been recommended for IOERT and has been identified as a risk-reduction intervention in the context of an IOERT risk analysis. Despite reports of fruitful experiences, information about in vivo dosimetry in intraoperative radiotherapy is somewhat scarce. Therefore, the aim of this paper is to report our experience in developing a program of in vivo dosimetry for IOERT, from both multidisciplinary and practical approaches, in a consistent patient series. We also report several current weaknesses. Reinforced TN-502RDM-H mobile metal oxide semiconductor field effect transistors (MOSFETs) and Gafchromic MD-55-2 films were used as a redundant in vivo treatment verification system with an Elekta Precise fixed linear accelerator for calibrations and treatments. In vivo dosimetry was performed in 45 patients in cases involving primary tumors or relapses. The most frequent primary tumors were breast (37 %) and colorectal (29 %), and local recurrences among relapses was 83 %. We made 50 attempts to measure with MOSFETs and 48 attempts to measure with films in the treatment zones. The surgical team placed both detectors with supervision from the radiation oncologist and following their instructions. The program was considered an overall success by the different professionals involved. The absorbed doses measured with MOSFETs and films were 93.8 ± 6.7 % and 97.9 ± 9.0 % (mean ± SD) respectively using a scale in which 90 % is the prescribed dose and 100 % is the maximum absorbed dose delivered by the beam. However, in 10 % of cases we experienced dosimetric problems due to detector misalignment, a situation which might be avoided with additional checks. The useful MOSFET lifetime length and the film sterilization procedure should also be

  9. 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

  10. Radiation accident dosimetry on plastics by EPR spectrometry.

    PubMed

    Trompier, F; Bassinet, C; Clairand, I

    2010-02-01

    In case of acute exposure to ionizing radiation, the dose absorbed by the victims has to be rapidly and accurately assessed in order to choose an appropriate medical treatment. Tooth enamel and bone biopsies measured by EPR spectrometry are often used as dose indicators, due to the good radiation sensitivity and the stability of EPR radiation-sensitive signals. Nevertheless, the invasive sampling of teeth and bones limits the application of this technique to retrospective dosimetry. Therefore, we have investigated an alternative non-invasive methodology. We have surveyed with EPR spectrometry the dosimetric properties of the plastics that can be found in personal effects such as glasses (CR-39, polycarbonate), mobile phones (PMMA, polycarbonate), watches and buttons. Dose response, signal stability and effects of storage conditions were investigated. Significant signal fading limits the use for radiation accident dosimetry. Few plastics present the required characteristics to be used in case of a radiation accident.

  11. 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

  12. 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

  13. Reviewing three dimensional dosimetry: basics and utilization as presented over 17 Years of DosGel and IC3Ddose

    NASA Astrophysics Data System (ADS)

    Schreiner, L. J.

    2017-05-01

    For seventeen years a community of basic and clinical scientists and researchers has been meeting bi-annually to promote the clinical advance of techniques to measure radiation dose in three dimensions. The interest in this dosimetry was motivated by its promise as an effective methodology for 3D measurement of the complex conformal dose distributions achieved by modern techniques such as Intensity Modulated and Volumetric Arc Radiation Therapy. Each of the International Conferences on 3D Radiation Dosimetry resulted in the publication of informative proceedings [1-8], the majority openly available on the internet. The proceedings included papers that: i) reviewed the basic science of the radiation sensitive materials used to accumulate the dose information, ii) introduced the science and engineering of the imaging systems required to read the information out, iii) described the work flows and systems required for efficient dosimetry, iv) reported the protocols required for reproducible dosimetry, and v) showed examples of clinical use illustrating advantage and limitations of the dosimetry. This paper is intended to use the framework provided by these proceedings to review the current 3D chemical dosimeters available and to discuss the requirements for their use. The paper describes how 3D dosimetry can complement other dose delivery validation approaches available in the clinic. It closes with some personal reflections of how the motivation for, and practice of, 3D dosimetry have changed (or not) over the years.

  14. 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

  15. Air core detectors for Cerenkov-free scintillation dosimetry of brachytherapy β-sources.

    PubMed

    Eichmann, Marion; Thomann, Benedikt

    2017-09-01

    Plastic scintillation detectors are used for dosimetry in small radiation fields with high dose gradients, e.g., provided by β-emitting sources like 106 Ru/ 106 Rh eye plaques. A drawback is a background signal caused by Cerenkov radiation generated by electrons passing the optical fibers (light guides) of this dosimetry system. Common approaches to correct for the Cerenkov signal are influenced by uncertainties resulting from detector positioning and calibration procedures. A different approach to avoid any correction procedure is to suppress the Cerenkov signal by replacing the solid core optical fiber with an air core light guide, previously shown for external beam therapy. In this study, the air core concept is modified and applied to the requirements of dosimetry in brachytherapy, proving its usability for measuring water energy doses in small radiation fields. Three air core detectors with different air core lengths are constructed and their performance in dosimetry for brachytherapy β-sources is compared with a standard two-fiber system, which uses a second fiber for Cerenkov correction. The detector systems are calibrated with a 90 Sr/ 90 Y secondary standard and tested for their angular dependence as well as their performance in depth dose measurements of 106 Ru/ 106 Rh sources. The signal loss relative to the standard detector increases with increasing air core length to a maximum value of 58.3%. At the same time, however, the percentage amount of Cerenkov light in the total signal is reduced from at least 12.1% to a value below 1.1%. There is a linear correlation between induced dose and measured signal current. The air core detectors determine the dose rates for 106 Ru/ 106 Rh sources without any form of correction for the Cerenkov signal. The air core detectors show advantages over the standard two-fiber system especially when measuring in radiation fields with high dose gradients. They can be used as simple one-fiber systems and allow for an almost

  16. 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

  17. Method of incident low-energy gamma-ray direction reconstruction in the GAMMA-400 gamma-ray space telescope

    NASA Astrophysics Data System (ADS)

    Kheymits, M. D.; Leonov, A. A.; Zverev, V. G.; Galper, A. M.; Arkhangelskaya, I. V.; Arkhangelskiy, A. I.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Yu T.; Bakaldin, A. V.; Dalkarov, O. D.

    2016-02-01

    The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work.

  18. 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

  19. Dosimetry Evolution in Teletherapy: Polimer Gel

    NASA Astrophysics Data System (ADS)

    Hamann, J. H.; Peixoto, J. G. P.

    2018-03-01

    Polymer gels evolution and chemical composition used in dosimetry. Type Composition First gels Folin’s Phenol or Gallic Acid Polymer Gel Agarose and N,N’-methylene-bis-acrylamide BANANA Bis, acrylamide, nitrous oxide and agarose BANG-1TM Bis, acrylamide, nitrogen and gelatin BANG-2TM Bis, acrylic acid, sodium hydroxide, nitrogen and gelatin BANG-3TM Bis, methacrylate acid, sodium hydroxide, nitrogen and gelatin MAGIC Methacrylate acid, ascorbic acid, gelatin and copper sulphate

  20. 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.

  1. Calibration of helical tomotherapy machine using EPR/alanine dosimetry.

    PubMed

    Perichon, Nicolas; Garcia, Tristan; François, Pascal; Lourenço, Valérie; Lesven, Caroline; Bordy, Jean-Marc

    2011-03-01

    Current codes of practice for clinical reference dosimetry of high-energy photon beams in conventional radiotherapy recommend using a 10 x 10 cm2 square field, with the detector at a reference depth of 10 cm in water and 100 cm source to surface distance (SSD) (AAPM TG-51) or 100 cm source-to-axis distance (SAD) (IAEA TRS-398). However, the maximum field size of a helical tomotherapy (HT) machine is 40 x 5 cm2 defined at 85 cm SAD. These nonstandard conditions prevent a direct implementation of these protocols. The purpose of this study is twofold: To check the absorbed dose in water and dose rate calibration of a tomotherapy unit as well as the accuracy of the tomotherapy treatment planning system (TPS) calculations for a specific test case. Both topics are based on the use of electron paramagnetic resonance (EPR) using alanine as transfer dosimeter between the Laboratoire National Henri Becquerel (LNHB) 60Co-gamma-ray reference beam and the Institut Curie's HT beam. Irradiations performed in the LNHB reference 60Co-gamma-ray beam allowed setting up the calibration method, which was then implemented and tested at the LNHB 6 MV linac x-ray beam, resulting in a deviation of 1.6% (at a 1% standard uncertainty) relative to the reference value determined with the standard IAEA TRS-398 protocol. HT beam dose rate estimation shows a difference of 2% with the value stated by the manufacturer at a 2% standard uncertainty. A 4% deviation between measured dose and the calculation from the tomotherapy TPS was found. The latter was originated by an inadequate representation of the phantom CT-scan values and, consequently, mass densities within the phantom. This difference has been explained by the mass density values given by the CT-scan and used by the TPS which were not the true ones. Once corrected using Monte Carlo N-Particle simulations to validate the accuracy of this process, the difference between corrected TPS calculations and alanine measured dose values was then

  2. Progress In The Development Of A Tomographic SPECT System For Online Dosimetry In BNCT

    NASA Astrophysics Data System (ADS)

    Minsky, D. M.; Valda, A.; Kreiner, A. J.; Burlon, A. A.; Green, S.; Wojnecki, C.; Ghani, Z.

    2010-08-01

    In boron neutron capture therapy (BNCT) the delivered dose to the patient depends both on the neutron beam characteristics and on the 10B body distribution which, in turn, is governed by the tumor specificity of the 10B drug-carrier. BNCT dosimetry is a complex matter due to the several interactions that neutrons can undergo with the different nuclei present in tissue. However the boron capture reaction 10B(n,α)7Li accounts for about 80 % of the total dose in a tumor with 40 ppm in 10B concentration. Present dosimetric methods are indirect, based on drug biodistribution statistical data and subjected to inter and intra-patient variability. In order to overcome the consequences of the concomitant high dosimetric uncertainties, we propose a SPECT (Single Photon Emission Tomography) approach based on the detection of the prompt gamma-ray (478 keV) emitted in 94 % of the cases from 7Li. For this purpose we designed, built and tested a prototype based on LaBr3(Ce) scintillators. Measurements on a head and tumor phantom were performed in the accelerator-based BNCT facility of the University of Birmingham (UK). They result in the first tomographic image of the 10B capture distribution obtained in a BNCT facility.

  3. Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

    NASA Technical Reports Server (NTRS)

    Galper, A.M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A.I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; hide

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approx. 0.01 deg (E(sub gamma) > 100 GeV), the energy resolution approx. 1% (E(sub gamma) > 10 GeV), and the proton rejection factor approx 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  4. 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.

  5. Cosmic Gamma-Rays

    Science.gov Websites

    [Argonne Logo] [DOE Logo] Cosmic Gamma-Rays Home Publications Talks People Students Argonne > ; HEP > Cosmic Gamma-Rays Projects VERITAS Past Projects TrICE What's New CTA Cosmic Gamma-Rays The

  6. Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu V.; hide

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons (+) positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approximately 0.01deg (E(sub gamma) greater than 100 GeV), the energy resolution approximately 1% (E(sub gamma) greater than 10 GeV), and the proton rejection factor approximately 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  7. International Intercomparison Exercise for Nuclear Accident Dosimetry at the DAF Using GODIVA-IV

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

    Hickman, David; Hudson, Becka

    The Nuclear Criticality Safety Program operated under the direction of Dr. Jerry McKamy completed the first NNSA Nuclear Accident Dosimetry exercise on May 27, 2016. Participants in the exercise were from Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), Savanah River Site (SRS), Pacific Northwest National Laboratory (PNNL), US Navy, the Atomic Weapons Establishment (United Kingdom) under the auspices of JOWOG 30, and the Institute for Radiological Protection and Nuclear Safety (France) by special invitation and NCSP memorandum of understanding. This exercise was the culmination of a series of Integral Experiment Requests (IER) thatmore » included the establishment of the Nuclear Criticality Experimental Research Center, (NCERC) the startup of the Godiva Reactor (IER-194), the establishment of a the Nuclear Accident Dosimetry Laboratory (NAD LAB) in Mercury, NV, and the determination of reference dosimetry values for the mixed neutron and photon radiation field of Godiva within NCERC.« less

  8. Terrestrial gamma-ray flashes monitor demonstrator on CubeSat

    NASA Astrophysics Data System (ADS)

    Dániel, V.; Pína, L.; Inneman, A.; Zadražil, V.; Báča, T.; Platkevič, M.; Stehlíková, V.; Nentvich, O.; Urban, M.

    2016-09-01

    The CubeSat mission with the demonstrator of miniaturized X-ray telescope is presented. The paper presents one of the mission objectives of using the instrument for remote sensing of the Terrestrial Gamma-ray Flashes (TGFs). TGFs are intense sources of gamma-rays associated with lightning bolt activity and tropical thunderstorms. The measurement of TGFs exists and was measured by sounding rockets, high altitude balloons or several satellite missions. Past satellite missions were equipped with different detectors working from 10 keV up to 10 MeV. The RHESSI mission spectrum measurement of TGFs shows the maximum counts per second around 75 keV. The used detectors were in general big in volume and cannot be utilized by the CubeSat mission. The presented CubeSat is equipped with miniaturized X-ray telescope using the Timepix non-cooled pixel detector. The detector works between 3 and 60 keV in counting mode (dosimetry) or in spectrum mode with resolution 5 keV. The wide-field X-ray "Lobster-eye" optics/collimator (depending on energy) is used with a view angle of 3 degrees for the source location definition. The UV detectors with FOV 30 degrees and 1.5 degrees are added parallel with the optic as a part of the telescope. The telescope is equipped with software distinguishing between the photons and other particles. Using this software the TGF's detection is possible also in the field of South Atlantic anomaly. For the total ionization dose, the additional detector is used based on Silicone (12-60 keV) and CdTe (20 keV - 1 MeV). The presented instruments are the demonstrators suitable also for the astrophysical, sun and moon observation. The paper shows the details of TGF's observation modes, detectors details, data processing and handling system and mission. The CubeSat launch is planned to summer 2016.

  9. Radiosurgery with the world's first fully robotized Leksell Gamma Knife PerfeXion in clinical use: a 200-patient prospective, randomized, controlled comparison with the Gamma Knife 4C.

    PubMed

    Régis, Jean; Tamura, Manabu; Guillot, Cécile; Yomo, Shoji; Muraciolle, Xavier; Nagaje, Mariko; Arka, Yasser; Porcheron, Denis

    2009-02-01

    The world's first Leksell Gamma Knife PerfeXion (Elekta Instrument AB, Stockholm, Sweden) for radiosurgery of the head and neck became operational at Timone University Hospital in Marseille on July 10, 2006. To allow strict evaluation of the capabilities, advantages, disadvantages, and limitations of this new technology, patients were enrolled in a prospective, randomized trial. In 66 working days, between July 10 and December 20, 2006, 363 patients were treated by gamma knife surgery at Timone University Hospital, Marseille. Of these patients, 200 were eligible for the comparative prospective study (inclusion criteria were informed consent obtained, tumor or vascular indication, and no previous radiosurgery or radiotherapy). In accordance with the blinded randomization process, 100 patients were treated with the Leksell Gamma Knife 4C (Elekta Instrument AB) and Gamma Knife 100 (Elekta Instrument AB) with the Leksell Gamma Knife PerfeXion. Dose planning parameters, dosimetry measurements on the patient's body, workflow, patient comfort, quality assurance procedure, and a series of other treatment-related parameters were systematically and prospectively evaluated in both arms of the trial. No technical failure of the treatment procedure was encountered. The new dose-planning system led to the use of composite shots in 39.4% of the patients. The median number of different collimator sizes used was larger with the PerfeXion than with the 4C (2 and 1, respectively). The mean number of isocenters used was lower (10.67 and 13.08, respectively). The median total treatment time was significantly shorter with the PerfeXion (40 and 60 minutes, respectively), but there was no significant difference in the median radiation time (34.02 and 33.40 minutes, respectively). The procedure was performed using only a single run in 98.99% of the PerfeXion cases and in 42% of the 4C cases. Collision risk on the 4C forced us to change the frame gamma angle for at least 1 shot in 24% of

  10. Design and study of the characteristics of a three electrode experimental ionization chamber for gamma ray dosimetry of spent fuel

    NASA Astrophysics Data System (ADS)

    Ahmad, N.; Mirza, Nasir M.; Mirza, Sikander M.; Rashid, T.; Tufail, M.; Khan, Liaquat A.

    1992-09-01

    The ( I, V) characteristics of two and three electrode ionization chamber filled with argon gas have been studied. To determine the sensitivity and the response with increase in exposure rate, the chamber was tested with a 60Co commercial irradiator. The response is linear up to more than 1.5 krad/h. The experimentally measured sensitivity of the chamber is 1.849×10 -13 A/cm 3 per rad/h when the argon gas pressure in the chamber is 1.24 GPa (180 psi). The effect of transparency of the intermediate electrod on the saturation current due to 137Cs gamma-rays has also been studied. The experimental results show that the electrode with holes of small diameter acts as a better intermediate electrode as compared to the electrodes without holes or with holes of a larger diameter. The chamber has also been teste with fission product gamma-rays from spent fuel elements of a typical pool type research reactor. The results indicate that the presence of an intermediate electrode lowers the operating voltage by 50% and reduces the slope in the plateau region.

  11. 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.

  12. 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

  13. Evaluation of Effective Sources in Uncertainty Measurements of Personal Dosimetry by a Harshaw TLD System

    PubMed Central

    Hosseini Pooya, SM; Orouji, T

    2014-01-01

    Background: The accurate results of the individual doses in personal dosimety which are reported by the service providers in personal dosimetry are very important. There are national / international criteria for acceptable dosimetry system performance. Objective: In this research, the sources of uncertainties are identified, measured and calculated in a personal dosimetry system by TLD. Method: These sources are included; inhomogeneity of TLDs sensitivity, variability of TLD readings due to limited sensitivity and background, energy dependence, directional dependence, non-linearity of the response, fading, dependent on ambient temperature / humidity and calibration errors, which may affect on the dose responses. Some parameters which influence on the above sources of uncertainty are studied for Harshaw TLD-100 cards dosimeters as well as the hot gas Harshaw 6600 TLD reader system. Results: The individual uncertainties of each sources was measured less than 6.7% in 68% confidence level. The total uncertainty was calculated 17.5% with 95% confidence level. Conclusion: The TLD-100 personal dosimeters as well as the Harshaw TLD-100 reader 6600 system show the total uncertainty value which is less than that of admissible value of 42% for personal dosimetry services. PMID:25505769

  14. Thermoluminescence of nanocrystalline CaSO4: Dy for gamma dosimetry and calculation of trapping parameters using deconvolution method

    NASA Astrophysics Data System (ADS)

    Mandlik, Nandkumar; Patil, B. J.; Bhoraskar, V. N.; Sahare, P. D.; Dhole, S. D.

    2014-04-01

    Nanorods of CaSO4: Dy having diameter 20 nm and length 200 nm have been synthesized by the chemical coprecipitation method. These samples were irradiated with gamma radiation for the dose varying from 0.1 Gy to 50 kGy and their TL characteristics have been studied. TL dose response shows a linear behavior up to 5 kGy and further saturates with increase in the dose. A Computerized Glow Curve Deconvolution (CGCD) program was used for the analysis of TL glow curves. Trapping parameters for various peaks have been calculated by using CGCD program.

  15. 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

  16. TH-C-17A-03: Dynamic Visualization and Dosimetry of IMRT and VMAT Treatment Plans by Video-Rate Imaging of Cherenkov Radiation in Pure Water

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

    Glaser, A; Andreozzi, J; Davis, S

    Purpose: A novel optical dosimetry technique for the QA and verification of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) radiotherapy plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: An intensified CCD camera (ICCD) was used to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a watermore » tank. The ICCD acquisition was gated to the Linac, operated for single pulse imaging, and binned to a resolution of 512×512 pixels. The resulting videos were analyzed temporally for regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR) and summed to obtain an overall light distribution, which was compared to the expected dose distribution from the TPS using a gammaindex analysis. Results: The chosen camera settings resulted in data at 23.5 frames per second. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.2% and 95.6% agreement between the light distribution and expected TPS dose distribution based upon a 3% / 3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans respectively. Conclusion: The results from this initial study demonstrate the first documented use of Cherenkov radiation for optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real-time nature of the acquisition, and upon future refinement may prove to be a robust and novel dosimetry method with both research and clinical applications. NIH R01CA109558 and R21EB

  17. 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

  18. Neutron dosimetry at a high-energy electron-positron collider

    NASA Astrophysics Data System (ADS)

    Bedogni, Roberto

    Electron-positron colliders with energy of hundreds of MeV per beam have been employed for studies in the domain of nuclear and sub-nuclear physics. The typical structure of such a collider includes an LINAC, able to produce both types of particles, an accumulator ring and a main ring, whose diameter ranges from several tens to hundred meters and allows circulating particle currents of several amperes per beam. As a consequence of the interaction of the primary particles with targets, shutters, structures and barriers, a complex radiation environment is produced. This paper addresses the neutron dosimetry issues associated with the operation of such accelerators, referring in particular to the DAΦ NE complex, operative since 1997 at INFN-Frascati National Laboratory (Italy). Special attention is given to the active and passive techniques used for the spectrometric and dosimetric characterization of the workplace neutron fields, for radiation protection dosimetry purposes.

  19. 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.

  20. Optical gamma thermometer

    DOEpatents

    Koster, Glen Peter; Xia, Hua; Lee, Boon Kwee

    2013-08-06

    An optical gamma thermometer includes a metal mass having a temperature proportional to a gamma flux within a core of a nuclear reactor, and an optical fiber cable for measuring the temperature of the heated metal mass. The temperature of the heated mass may be measured by using one or more fiber grating structures and/or by using scattering techniques, such as Raman, Brillouin, and the like. The optical gamma thermometer may be used in conjunction with a conventional reactor heat balance to calibrate the local power range monitors over their useful in-service life. The optical gamma thermometer occupies much less space within the in-core instrument tube and costs much less than the conventional gamma thermometer.

  1. Medical dosimetry in Hungary

    NASA Astrophysics Data System (ADS)

    Turák, O.; Osvay, M.; Ballay, L.

    2012-09-01

    Radiation exposure of medical staff during cardiological and radiological procedures was investigated. The exposure of medical staff is directly connected to patient exposure. The aim of this study was to determine the distribution of doses on uncovered part of body of medical staff using LiF thermoluminescent (TL) dosimeters in seven locations. Individual Kodak film dosimeters (as authorized dosimetry system) were used for the assessment of medical staff's effective dose. Results achieved on dose distribution measurements confirm that wearing only one film badge under the lead apron does not provide enough information on the personal dose. The value of estimated annual doses on eye lens and extremities (fingers) were in good correlation with international publications.

  2. Development of a personal dosimetry system based on optically stimulated luminescence of alpha-Al2O3:C for mixed radiation fields.

    PubMed

    Lee, S Y; Lee, K J

    2001-04-01

    To develop a personal optically stimulated luminescence (OSL) dosimetry system for mixed radiation fields using alpha-Al2O3:C, a discriminating badge filter system was designed by taking advantage of its optically stimulable properties and energy dependencies. This was done by designing a multi-element badge system for powder layered alpha-Al2O3:C material and an optical reader system based on high-intensity blue light-emitting diode (LED). The design of the multielement OSL dosimeter badge system developed allows the measurement of a personal dose equivalent value Hp(d) in mixed radiation fields of beta and gamma. Dosimetric properties of the personal OSL dosimeter badge system investigated here were the dose response, energy response and multi-readability. Based on the computational simulations and experiments of the proposed dosimeter design, it was demonstrated that a multi-element dosimeter system with an OSL technology based on alpha-Al2O3:C is suitable to obtain personal dose equivalent information in mixed radiation fields.

  3. Time-resolved optically stimulated luminescence of Al2O3:C for ion beam therapy dosimetry

    NASA Astrophysics Data System (ADS)

    Yukihara, Eduardo G.; Doull, Brandon A.; Ahmed, Md; Brons, Stephan; Tessonnier, Thomas; Jäkel, Oliver; Greilich, Steffen

    2015-09-01

    The objective of this study was to characterize the time-resolved (TR) optically stimulated luminescence (OSL) from Al2O3:C detectors and investigate methodologies to improve the accuracy of these detectors in ion beam therapy dosimetry, addressing the reduction in relative response to high linear energy transfer (LET) particles common to solid-state detectors. Al2O3:C OSL detectors (OSLDs) were exposed to proton, 4He, 12C and 16O beams in 22 particle/energy combinations and read using a custom-built TR-OSL reader. The OSL response {{r}\\text{OSL}} , relative to 60Co gamma dose to water, and the ratio between the UV and blue OSL emission bands of Al2O3:C (UV/blue ratio) were determined as a function of the LET. Monte-Carlo simulations with the multi-purpose interaction and transport code FLUKA were used to estimate the absorbed doses and particle energy spectra in the different irradiation conditions. The OSL responses {{r}\\text{OSL}} varied from 0.980 (0.73 keV μm-1) to 0.288 (120.8 keV μm-1). The OSL UV/blue ratio varied by a factor of two in the investigated LET range, but the variation for 12C beams was only 11%. OSLDs were also irradiated at different depths of carbon ion spread-out Bragg peaks (SOBPs), where it was shown that doses could be obtained with an accuracy of  ±2.0% at the entrance channel and within the SOBP using correction factors calculated based on the OSL responses obtained in this study. The UV/blue ratio did not allow accurate estimation of the dose-averaged LET for 12C SOBPs, although the values obtained can be explained with the data obtained in this study and the additional information provided by the Monte-Carlo simulations. The results demonstrate that accurate OSLD dosimetry can be performed in ion beam therapy using appropriate corrections for the OSL response.

  4. 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.

  5. Implications of Gamma-Ray Transparency Constraints in Blazars: Minimum Distances and Gamma-Ray Collimation

    NASA Technical Reports Server (NTRS)

    Becker, Peter A.; Kafatos, Menas

    1995-01-01

    We develop a general expression for the gamma - gamma absorption coefficient, alpha(sub gamma(gamma)) for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray-emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius, R(sub 0), and the inner radius, R(sub ms) which is the radius of marginal stability for a Schwarzschild black hole. We use our result for alpha(sub gamma(gamma)) to calculate the gamma - gamma optical depth, tau(sub gamma(gamma)) for gamma - rays created at height z and propagating at angle Phi relative to the disk axis, and we show that for Phi = 0 and z greater than or approx equal to R(sub 0), tau(sub gamma(gamma)) proportional to Epsilon(sup alpha)z(sup -2(alpha) - 3), where alpha is the X-ray spectral index and Epsilon is the gamma - ray energy. As an application, we use our formalism to compute the minimum distance between the central black hole and the site of production of the gamma-rays detected by EGRET during the 1991 June flare of 3C 279. In order to obtain an upper limit, we assume that all of the X-rays observed contemporaneously by Ginga were emitted by the disk. Our results suggest that the observed gamma - rays may have originated within less than or approx equal to 45 GM/sq c from a black hole of mass greater than or approx equal to 10(exp 9) solar mass, perhaps in active plasma located above the central funnel of the accretion disk. This raises the possibility of establishing a direct connection between the production of the observed gamma - rays and the accretion of material onto the black hole. We also consider the variation of the optical depth as a function of the angle of propagation Phi. Our results indicate that the "focusing" of the gamma - rays along the disk axis due to pair production is strong enough to explain the observed degree of alignment in blazar sources. If the gamma - rays are produced isotropically

  6. Thermoluminescence dosimetry applied to in vivo dose measurements for total body irradiation techniques.

    PubMed

    Duch, M A; Ginjaume, M; Chakkor, H; Ortega, X; Jornet, N; Ribas, M

    1998-06-01

    In total body irradiation (TBI) treatments in vivo dosimetry is recommended because it makes it possible to ensure the accuracy and quality control of dose delivery. The aim of this work is to set up an in vivo thermoluminescence dosimetry (TLD) system to measure the dose distribution during the TBI technique used prior to bone marrow transplant. Some technical problems due to the presence of lung shielding blocks are discussed. Irradiations were performed in the Hospital de la Santa Creu i Sant Pau by means of a Varian Clinac-1800 linear accelerator with 18 MV X-ray beams. Different TLD calibration experiments were set up to optimize in vivo dose assessment and to analyze the influence on dose measurement of shielding blocks. An algorithm to estimate midplane doses from entrance and exit doses is proposed and the estimated dose in critical organs is compared to internal dose measurements performed in an Alderson anthropomorphic phantom. The predictions of the dose algorithm, even in heterogeneous zones of the body such as the lungs, are in good agreement with the experimental results obtained with and without shielding blocks. The differences between measured and predicted values are in all cases lower than 2%. The TLD system described in this work has been proven to be appropriate for in vivo dosimetry in TBI irradiations. The described calibration experiments point out the difficulty of calibrating an in vivo dosimetry system when lung shielding blocks are used.

  7. Design and performance of the GAMMA-400 gamma-ray telescope for dark matter searches

    NASA Astrophysics Data System (ADS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Moiseev, A. A.; Mocchiutti, E.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.; Zirakashvili, V. N.

    2013-02-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is ~0.01° (Eγ > 100 GeV), the energy resolution ~1% (Eγ > 10 GeV), and the proton rejection factor ~106. GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  8. TU-FG-201-06: Remote Dosimetric Auditing for Clinical Trials Using EPID Dosimetry: A Pilot Study

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

    Miri, N; Legge, K; Greer, P

    2016-06-15

    Purpose: To perform a pilot study for remote dosimetric credentialing of intensity modulated radiation therapy (IMRT) based clinical trials. The study introduces a novel, time efficient and inexpensive dosimetry audit method for multi-center credentialing. The method employs electronic portal imaging device (EPID) to reconstruct delivered dose inside a virtual flat/cylindrical water phantom. Methods: Five centers, including different accelerator types and treatment planning systems (TPS), were asked to download two CT data sets of a Head and Neck (H&N) and Postprostatectomy (P-P) patients to produce benchmark plans. These were then transferred to virtual flat and cylindrical phantom data sets that weremore » also provided. In-air EPID images of the plans were then acquired, and the data sent to the central site for analysis. At the central site, these were converted to DICOM format, all images were used to reconstruct 2D and 3D dose distributions inside respectively the flat and cylindrical phantoms using inhouse EPID to dose conversion software. 2D dose was calculated for individual fields and 3D dose for the combined fields. The results were compared to corresponding TPS doses. Three gamma criteria were used, 3%3mm-3%/2mm–2%/2mm with a 10% dose threshold, to compare the calculated and prescribed dose. Results: All centers had a high pass rate for the criteria of 3%/3 mm. For 2D dose, the average of centers mean pass rate was 99.6% (SD: 0.3%) and 99.8% (SD: 0.3%) for respectively H&N and PP patients. For 3D dose, 3D gamma was used to compare the model dose with TPS combined dose. The mean pass rate was 97.7% (SD: 2.8%) and 98.3% (SD: 1.6%). Conclusion: Successful performance of the method for the pilot centers establishes the method for dosimetric multi-center credentialing. The results are promising and show a high level of gamma agreement and, the procedure is efficient, consistent and inexpensive. Funding has been provided from Department of Radiation

  9. Sci-Thur PM: YIS - 07: Monte Carlo simulations to obtain several parameters required for electron beam dosimetry.

    PubMed

    Muir, B; Rogers, D; McEwen, M

    2012-07-01

    When current dosimetry protocols were written, electron beam data were limited and had uncertainties that were unacceptable for reference dosimetry. Protocols for high-energy reference dosimetry are currently being updated leading to considerable interest in accurate electron beam data. To this end, Monte Carlo simulations using the EGSnrc user-code egs_chamber are performed to extract relevant data for reference beam dosimetry. Calculations of the absorbed dose to water and the absorbed dose to the gas in realistic ion chamber models are performed as a function of depth in water for cobalt-60 and high-energy electron beams between 4 and 22 MeV. These calculations are used to extract several of the parameters required for electron beam dosimetry - the beam quality specifier, R 50 , beam quality conversion factors, k Q and k R50 , the electron quality conversion factor, k' R50 , the photon-electron conversion factor, k ecal , and ion chamber perturbation factors, P Q . The method used has the advantage that many important parameters can be extracted as a function of depth instead of determination at only the reference depth as has typically been done. Results obtained here are in good agreement with measured and other calculated results. The photon-electron conversion factors obtained for a Farmer-type NE2571 and plane-parallel PTW Roos, IBA NACP-02 and Exradin A11 chambers are 0.903, 0.896, 0.894 and 0.906, respectively. These typically differ by less than 0.7% from the contentious TG-51 values but have much smaller systematic uncertainties. These results are valuable for reference dosimetry of high-energy electron beams. © 2012 American Association of Physicists in Medicine.

  10. The internal dosimetry code PLEIADES.

    PubMed

    Fell, T P; Phipps, A W; Smith, T J

    2007-01-01

    The International Commission on Radiological Protection (ICRP) has published dose coefficients for the ingestion or inhalation of radionuclides in a series of reports covering intakes by workers and members of the public, including children and pregnant or lactating women. The calculation of these coefficients divides naturally into two distinct parts-the biokinetic and dosimetric. This paper describes in detail the methods used to solve the biokinetic problem in the generation of dose coefficients on behalf of the ICRP, as implemented in the Health Protection Agency's internal dosimetry code PLEIADES. A summary of the dosimetric treatment is included.

  11. MECHANISTIC DOSIMETRY MODELS OF NANOMATERIAL DEPOSITION IN THE RESPIRATORY TRACT

    EPA Science Inventory

    Accurate health risk assessments of inhalation exposure to nanomaterials will require dosimetry models that account for interspecies differences in dose delivered to the respiratory tract. Mechanistic models offer the advantage to interspecies extrapolation that physicochemica...

  12. Neutron Exposure Parameters for the Dosimetry Capsule in the Heavy-Section Steel Irradiation Program Tenth Irradiation Series

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

    C.A. Baldwin; F.B.K. Kam; I. Remec

    1998-10-01

    This report describes the computational methodology for the least-squares adjustment of the dosimetry data from the HSSI 10.OD dosimetry capsule with neutronics calculations. It presents exposure rates at each dosimetry location for the neutron fluence greater than 1.0 MeV, fluence greater than 0.1 MeV, and displacements per atom. Exposure parameter distributions are also described in terms of three- dimensional fitting functions. When fitting functions are used it is suggested that an uncertainty of 6% (1 o) should be associated with the exposure rate values. The specific activity of each dosimeter at the end of irradiation is listed in the Appendix.

  13. Increase in neutrophil Fc gamma receptor I expression following interferon gamma treatment in rheumatoid arthritis.

    PubMed Central

    Goulding, N J; Knight, S M; Godolphin, J L; Guyre, P M

    1992-01-01

    The therapeutic potential of interferon gamma (IFN gamma) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN gamma (rhIFN gamma), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis. The levels of Fc gamma receptors on peripheral blood neutrophils were measured at baseline and after 21 days of once daily, subcutaneous injections of rhIFN gamma or placebo. An induction of neutrophil Fc gamma receptor type I (Fc gamma RI) was seen in the group of patients receiving recombinant human rhIFN gamma but not in those receiving placebo. No change in the expression of Fc gamma RII or Fc gamma RIII was detected. The amount of induction of Fc gamma RI detected on the neutrophils of patients receiving rhIFN gamma did not correlate with clinical measures of response at either 21 days or at the end of the study (24 weeks). No significant clinical responses were observed in the rhIFN gamma group at these times. These data confirm that the reported in vitro effect of IFN gamma on human neutrophil Fc receptor expression can be reproduced in vivo. PMID:1534001

  14. Increase in neutrophil Fc gamma receptor I expression following interferon gamma treatment in rheumatoid arthritis.

    PubMed

    Goulding, N J; Knight, S M; Godolphin, J L; Guyre, P M

    1992-04-01

    The therapeutic potential of interferon gamma (IFN gamma) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN gamma (rhIFN gamma), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis. The levels of Fc gamma receptors on peripheral blood neutrophils were measured at baseline and after 21 days of once daily, subcutaneous injections of rhIFN gamma or placebo. An induction of neutrophil Fc gamma receptor type I (Fc gamma RI) was seen in the group of patients receiving recombinant human rhIFN gamma but not in those receiving placebo. No change in the expression of Fc gamma RII or Fc gamma RIII was detected. The amount of induction of Fc gamma RI detected on the neutrophils of patients receiving rhIFN gamma did not correlate with clinical measures of response at either 21 days or at the end of the study (24 weeks). No significant clinical responses were observed in the rhIFN gamma group at these times. These data confirm that the reported in vitro effect of IFN gamma on human neutrophil Fc receptor expression can be reproduced in vivo.

  15. Analysis of regional radiotherapy dosimetry audit data and recommendations for future audits

    PubMed Central

    Palmer, A; Mzenda, B; Kearton, J; Wills, R

    2011-01-01

    Objectives Regional interdepartmental dosimetry audits within the UK provide basic assurances of the dosimetric accuracy of radiotherapy treatments. Methods This work reviews several years of audit results from the South East Central audit group including megavoltage (MV) and kilovoltage (kV) photons, electrons and iodine-125 seeds. Results Apart from some minor systematic errors that were resolved, the results of all audits have been within protocol tolerances, confirming the long-term stability and agreement of basic radiation dosimetric parameters between centres in the audit region. There is some evidence of improvement in radiation dosimetry with the adoption of newer codes of practice. Conclusion The value of current audit methods and the limitations of peer-to-peer auditing is discussed, particularly the influence of the audit schedule on the results obtained, where no “gold standard” exists. Recommendations are made for future audits, including an essential requirement to maintain the monitoring of basic fundamental dosimetry, such as MV photon and electron output, but audits must also be developed to include new treatment technologies such as image-guided radiotherapy and address the most common sources of error in radiotherapy. PMID:21159805

  16. Gamma Knife

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? The Gamma Knife® and its associated ... in size. top of page How does the equipment work? The Gamma Knife® utilizes a technique called ...

  17. Gamma-400 Science Objectives Built on the Current HE Gamma-Ray and CR Results

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander; Mitchell, John; Thompson, David

    2012-01-01

    The main scientific interest of the Russian Gamma-400 team: Observe gamma-rays above approximately 50 GeV with excellent energy and angular resolution with the goals of: (1) Studying the fine spectral structure of the isotropic high-energy gamma-radiation, (2) Attempting to identify the many still-unidentified Fermi-LAT gamma-ray sources. Gamma-400 will likely be the only space-based gamma-ray observatory operating at the end of the decade. In our proposed Gamma-400-LE version, it will substantially improve upon the capabilities of Fermi LAT and AGILE in both LE and HE energy range. Measuring gamma-rays from approx 20 MeV to approx 1 TeV for at least 7 years, Gamma-400-LE will address the topics of dark matter, cosmic ray origin and propagation, neutron stars, flaring pulsars, black holes, AGNs, GRBs, and actively participate in multiwavelength campaigns.

  18. L Band EPR Tooth Dosimetry for Heavy Ion Irradiation

    PubMed Central

    Yamaguchi, Ichiro; Sato, Hitoshi; Kawamura, Hiraku; Hamano, Tsuyoshi; Yoshii, Hiroshi; Suda, Mitsuru; Miyake, Minoru; Kunugita, Naoki

    2016-01-01

    Electron Paramagnetic Resonance (EPR) tooth dosimetry is being developed as a device to rapidly assess large populations that were potentially exposed to radiation during a major radiation accident or terrorist event. While most exposures are likely to be due to fallout and therefore involve low linear energy transfer (LET) radiation, there is also a potential for exposures to high LET radiation, for which the effect on teeth has been less well characterized by EPR. Therefore, the aim of this paper is to acquire fundamental response curves for high LET radiation in tooth dosimetry using L band EPR. For this purpose, we exposed human teeth to high energy carbon ions using the heavy ion medical accelerator in Chiba at the National Institute of Radiological Sciences. The primary findings were that EPR signals for carbon ion irradiation were about one-tenth the amplitude of the response to the same dose of 150 kVp X-rays. PMID:27542817

  19. Preliminary thermoluminescence and optically stimulated luminescence investigation of commercial pharmaceutical preparations towards the drug sterilization dosimetry.

    PubMed

    Kazakis, Nikolaos A; Tsirliganis, Nestor C; Kitis, George

    2014-09-01

    Drug sterilization with ionizing radiation is a well-established technology and is gaining ground the last decades due to its numerous advantages. Identification of irradiated drugs would be interesting and, in this respect, the present work aims, for the first time to the authors' best knowledge, to explore whether OSL and TL can be employed as methods for post-sterilization dosimetry on commercial drugs, i.e., as tools for the detection of irradiated drugs. Five widely used drugs, i.e., Daktarin(®), Aspirin(®), Panadol(®), Brufen(®) and Procef(®), are used for this purpose. Preliminary findings are very promising towards the post-sterilization dosimetry and the use of commercial drugs for normal and/or accidental dosimetry. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Genomic sequences of murine gamma B- and gamma C-crystallin-encoding genes: promoter analysis and complete evolutionary pattern of mouse, rat and human gamma-crystallins.

    PubMed

    Graw, J; Liebstein, A; Pietrowski, D; Schmitt-John, T; Werner, T

    1993-12-22

    The murine genes, gamma B-cry and gamma C-cry, encoding the gamma B- and gamma C-crystallins, were isolated from a genomic DNA library. The complete nucleotide (nt) sequences of both genes were determined from 661 and 711 bp, respectively, upstream from the first exon to the corresponding polyadenylation sites, comprising more than 2650 and 2890 bp, respectively. The new sequences were compared to the partial cDNA sequences available for the murine gamma B-cry and gamma C-cry, as well as to the corresponding genomic sequences from rat and man, at both the nt and predicted amino acid (aa) sequence levels. In the gamma B-cry promoter region, a canonical CCAAT-box, a TATA-box, putative NF-I and C/EBP sites were detected. An R-repeat is inserted 366 bp upstream from the transcription start point. In contrast, the gamma C-cry promoter does not contain a CCAAT-box, but some other putative binding sites for transcription factors (AP-2, UBP-1, LBP-1) were located by computer analysis. The promoter regions of all six gamma-cry from mouse, rat and human, except human psi gamma F-cry, were analyzed for common sequence elements. A complex sequence element of about 70-80 bp was found in the proximal promoter, which contains a gamma-cry-specific and almost invariant sequence (crygpel) of 14 nt, and ends with the also invariant TATA-box. Within the complex sequence element, a minimum of three further features specific for the gamma A-, gamma B- and gamma D/E/F-cry genes can be defined, at least two of which were recently shown to be functional. In addition to these four sequence elements, a subtype-specific structure of inverted repeats with different-sized spacers can be deduced from the multiple sequence alignment. A phylogenetic analysis based on the promoter region, as well as the complete exon 3 of all gamma-cry from mouse, rat and man, suggests separation of only five gamma-cry subtypes (gamma A-, gamma B-, gamma C-, gamma D- and gamma E/F-cry) prior to species separation.

  1. Predicting diffusion paths and interface motion in gamma/gamma + beta, Ni-Cr-Al diffusion couples

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.; Heckel, R. W.

    1987-01-01

    A simplified model has been developed to predict Beta recession and diffusion paths in ternary gamma/gamma + beta diffusion couples (gamma:fcc, beta: NiAl structure). The model was tested by predicting beta recession and diffusion paths for four gamma/gamma + beta, Ni-Cr-Al couples annealed for 100 hours at 1200 C. The model predicted beta recession within 20 percent of that measured for each of the couples. The model also predicted shifts in the concentration of the gamma phase at the gamma/gamma + beta interface within 2 at. pct Al and 6 at. pct Cr of that measured in each of the couples. A qualitative explanation based on simple kinetic and mass balance arguments has been given which demonstrates the necessity for diffusion in the two-phase region of certain gamma/gamma + beta, Ni-Cr-Al couples.

  2. CIEMAT EXTERNAL DOSIMETRY SERVICE: ISO/IEC 17025 ACCREDITATION AND 3 Y OF OPERATIONAL EXPERIENCE AS AN ACCREDITED LABORATORY.

    PubMed

    Romero, A M; Rodríguez, R; López, J L; Martín, R; Benavente, J F

    2016-09-01

    In 2008, the CIEMAT Radiation Dosimetry Service decided to implement a quality management system, in accordance with established requirements, in order to achieve ISO/IEC 17025 accreditation. Although the Service comprises the approved individual monitoring services of both external and internal radiation, this paper is specific to the actions taken by the External Dosimetry Service, including personal and environmental dosimetry laboratories, to gain accreditation and the reflections of 3 y of operational experience as an accredited laboratory. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. Comparison of gamma-gamma Phase Coarsening Responses of Three Powder Metal Disk Superalloys

    NASA Technical Reports Server (NTRS)

    Gabb, T. P.; Gayda, J.; Johnson, D. F.; MacKay, R. A.; Rogers, R. B.; Sudbrack, C. K.; Garg, A.; Locci, I. E.; Semiatin, S. L.; Kang, E.

    2016-01-01

    The phase microstructures of several powder metal (PM) disk superalloys were quantitatively evaluated. Contents, chemistries, and lattice parameters of gamma and gamma strengthening phase were determined for conventionally heat treated Alloy 10, LSHR, and ME3 superalloys, after electrolytic phase extractions. Several of long term heat treatments were then performed, to allow quantification of the precipitation, content, and size distribution of gamma at a long time interval to approximate equilibrium conditions. Additional coarsening heat treatments were performed at multiple temperatures and shorter time intervals, to allow quantification of the precipitation, contents and size distributions of gamma at conditions diverging from equilibrium. Modest differences in gamma and gamma lattice parameters and their mismatch were observed among the alloys, which varied with heat treatment. Yet, gamma coarsening rates were very similar for all three alloys in the heat treatment conditions examined. Alloy 10 had higher gamma dissolution and formation temperatures than LSHR and ME3, but a lower lattice mismatch, which was slightly positive for all three alloys at room temperature. The gamma precipitates of Alloy 10 appeared to remain coherent at higher temperatures than for LSHR and ME3. Higher coarsening rates were observed for gamma precipitates residing along grain boundaries than for those within grains in all three alloys, during slow-moderate quenching from supersolvus solution heat treatments, and during aging at temperatures of 843 C and higher.

  9. 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

  10. Micro-Fabricated Solid-State Radiation Detectors for Active Personal Dosimetry

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.; Chen, Liang-Yu

    2007-01-01

    Active radiation dosimetry is important to human health and equipment functionality for space applications outside the protective environment of a space station or vehicle. This is especially true for long duration missions to the moon, where the lack of a magnetic field offers no protection from space radiation to those on extravehicular activities. In order to improve functionality, durability and reliability of radiation dosimeters for future NASA lunar missions, single crystal silicon carbide devices and scintillating fiber detectors are currently being investigated for applications in advanced extravehicular systems. For many years, NASA Glenn Research Center has led significant efforts in silicon carbide semiconductor technology research and instrumentation research for sensor applications under extreme conditions. This report summarizes the technical progress and accomplishments toward characterization of radiation-sensing components for the recommendation of their fitness for advanced dosimetry development.

  11. How feasible is remote 3D dosimetry for MR guided Radiation Therapy (MRgRT)?

    NASA Astrophysics Data System (ADS)

    Mein, S.; Rankine, L.; Miles, D.; Juang, T.; Cai, B.; Curcuru, A.; Mutic, S.; Fenoli, J.; Adamovics, J.; Li, H.; Oldham, M.

    2017-05-01

    To develop and apply a remote dosimetry protocol with PRESAGE® radiochromic plastic and optical-CT readout in the validation of MRI guided radiation therapy (MRgRT) treatments (MRIdian® by ViewRay®). Through multi-institutional collaboration we performed PRESAGE® dosimetry studies in 4ml cuvettes to investigate dose-response linearity, MR-compatibility, and energy-independence. An open calibration field and symmetrical 3-field plans were delivered to 10cm diameter PRESAGE® to examine percent depth dose and response uniformity under a magnetic field. Evidence of non-linear dose response led to a large volume PRESAGE® study where small corrections were developed for temporally- and spatially-dependent behaviors observed between irradiation and delayed readout. TG-119 plans were created in the MRIdian® TPS and then delivered to 14.5cm 2kg PRESAGE® dosimeters. Through the domestic investigation of an off-site MRgRT system, a refined 3D remote dosimetry protocol is presented capable of validation of advanced MRgRT radiation treatments.

  12. 20170915 - EPA’s Rapid Exposure and Dosimetry Project (Alberta Health)

    EPA Science Inventory

    The Chemical Safety for Sustainability Research Program includes the Rapid Exposure and Dosimetry (RED) project. RED advances high throughput research in exposure modeling and toxicokinetics. This presentation is an overview of publicly available tools developed by the RED projec...

  13. PROcEED: Probabilistic reverse dosimetry approaches for estimating exposure distributions

    EPA Science Inventory

    As increasing amounts of biomonitoring survey data become available, a new discipline focused on converting such data into estimates of chemical exposures has developed. Reverse dosimetry uses a pharmacokinetic model along with measured biomarker concentrations to determine the p...

  14. Fostering a culture of interprofessional education for radiation therapy and medical dosimetry students

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

    Lavender, Charlotte, E-mail: charlavender@gmail.com; Miller, Seth; Church, Jessica

    A less-studied aspect of radiation therapy and medical dosimetry education is experiential learning through attendance at interprofessional conferences. University of North Carolina radiation therapy and medical dosimetry students regularly attended morning conferences and daily pretreatment peer review, including approximately 145 hours of direct interaction with medical attending physicians and residents, medical physicists, and other faculty. We herein assessed the effect of their participation in these interprofessional conferences on knowledge and communication. The students who graduated from our radiation therapy and medical dosimetry programs who were exposed to the interprofessional education initiative were compared with those who graduated in the previousmore » years. The groups were compared with regard to their knowledge (as assessed by grades on end-of-training examinations) and team communication (assessed via survey). The results for the 2 groups were compared via exact tests. There was a trend for the examination scores for the 2012 cohort to be higher than for the 2007 to 2011 groups. Survey results suggested that students who attended the interprofessional education sessions were more comfortable speaking with attending physicians, residents, physicists, and faculty compared with earlier students who did not attend these educational sessions. Interprofessional education, particularly vertical integration, appears to provide an enhanced educational experience both in regard to knowledge (per the examination scores) and in building a sense of communication (via the survey results). Integration of interprofessional education into radiation therapy and medical dosimetry educational programs may represent an opportunity to enrich the learning experience in multiple ways and merits further study.« less

  15. 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

  16. Influence of experimental parameters on sonochemistry dosimetries: KI oxidation, Fricke reaction and H2O2 production.

    PubMed

    Merouani, Slimane; Hamdaoui, Oualid; Saoudi, Fethi; Chiha, Mahdi

    2010-06-15

    Central events of the ultrasonic action are the cavitation bubbles that can be considered as microreactors. Adiabatic collapse of cavitation bubbles leads to the formation of reactive species such as hydroxyl radicals (*OH), hydrogen peroxide (H(2)O(2)) and hydroperoxyl radicals (HOO*). Several chemical methods were used to detect the production of these reactive moieties in sonochemistry. In this work, the influence of several operational parameters on the sonochemistry dosimetries namely KI oxidation, Fricke reaction and H(2)O(2) production using 300 kHz ultrasound was investigated. The main experimental parameters showing significant effect in KI oxidation dosimetry were initial KI concentration, acoustic power and pH. The solution temperature showed restricted influence on KI oxidation. The acoustic power and liquid temperature highly affected Fricke reaction dosimetry. Operational conditions having important influence on H(2)O(2) formation were acoustic power, solution temperature and pH. For the three tested dosimetries, the sonochemical efficiency was independent of liquid volume. Copyright 2010 Elsevier B.V. All rights reserved.

  17. SU-E-T-133: Assessing IMRT Treatment Delivery Accuracy and Consistency On a Varian TrueBeam Using the SunNuclear PerFraction EPID Dosimetry Software

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

    Dieterich, S; Trestrail, E; Holt, R

    2015-06-15

    Purpose: To assess if the TrueBeam HD120 collimator is delivering small IMRT fields accurately and consistently throughout the course of treatment using the SunNuclear PerFraction software. Methods: 7-field IMRT plans for 8 canine patients who passed IMRT QA using SunNuclear Mapcheck DQA were selected for this study. The animals were setup using CBCT image guidance. The EPID fluence maps were captured for each treatment field and each treatment fraction, with the first fraction EPID data serving as the baseline for comparison. The Sun Nuclear PerFraction Software was used to compare the EPID data for subsequent fractions using a Gamma (3%/3mm)more » pass rate of 90%. To simulate requirements for SRS, the data was reanalyzed using a Gamma (3%/1mm) pass rate of 90%. Low-dose, low- and high gradient thresholds were used to focus the analysis on clinically relevant parts of the dose distribution. Results: Not all fractions could be analyzed, because during some of the treatment courses the DICOM tags in the EPID images intermittently change from CU to US (unspecified), which would indicate a temporary loss of EPID calibration. This technical issue is still being investigated. For the remaining fractions, the vast majority (7/8 of patients, 95% of fractions, and 96.6% of fields) are passing the less stringent Gamma criteria. The more stringent Gamma criteria caused a drop in pass rate (90 % of fractions, 84% of fields). For the patient with the lowest pass rate, wet towel bolus was used. Another patient with low pass rates experienced masseter muscle wasting. Conclusion: EPID dosimetry using the PerFraction software demonstrated that the majority of fields passed a Gamma (3%/3mm) for IMRT treatments delivered with a TrueBeam HD120 MLC. Pass rates dropped for a DTA of 1mm to model SRS tolerances. PerFraction pass rates can flag missing bolus or internal shields. Sanjeev Saini is an employee of Sun Nuclear Corporation. For this study, a pre-release version of Per

  18. The gamma-ray observatory

    NASA Technical Reports Server (NTRS)

    1991-01-01

    An overview is given of the Gamma Ray Observatory (GRO) mission. Detection of gamma rays and gamma ray sources, operations using the Space Shuttle, and instruments aboard the GRO, including the Burst and Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET) are among the topics surveyed.

  19. High-frequency gamma oscillations coexist with low-frequency gamma oscillations in the rat visual cortex in vitro.

    PubMed

    Oke, Olaleke O; Magony, Andor; Anver, Himashi; Ward, Peter D; Jiruska, Premysl; Jefferys, John G R; Vreugdenhil, Martin

    2010-04-01

    Synchronization of neuronal activity in the visual cortex at low (30-70 Hz) and high gamma band frequencies (> 70 Hz) has been associated with distinct visual processes, but mechanisms underlying high-frequency gamma oscillations remain unknown. In rat visual cortex slices, kainate and carbachol induce high-frequency gamma oscillations (fast-gamma; peak frequency approximately 80 Hz at 37 degrees C) that can coexist with low-frequency gamma oscillations (slow-gamma; peak frequency approximately 50 Hz at 37 degrees C) in the same column. Current-source density analysis showed that fast-gamma was associated with rhythmic current sink-source sequences in layer III and slow-gamma with rhythmic current sink-source sequences in layer V. Fast-gamma and slow-gamma were not phase-locked. Slow-gamma power fluctuations were unrelated to fast-gamma power fluctuations, but were modulated by the phase of theta (3-8 Hz) oscillations generated in the deep layers. Fast-gamma was spatially less coherent than slow-gamma. Fast-gamma and slow-gamma were dependent on gamma-aminobutyric acid (GABA)(A) receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and gap-junctions, their frequencies were reduced by thiopental and were weakly dependent on cycle amplitude. Fast-gamma and slow-gamma power were differentially modulated by thiopental and adenosine A(1) receptor blockade, and their frequencies were differentially modulated by N-methyl-D-aspartate (NMDA) receptors, GluK1 subunit-containing receptors and persistent sodium currents. Our data indicate that fast-gamma and slow-gamma both depend on and are paced by recurrent inhibition, but have distinct pharmacological modulation profiles. The independent co-existence of fast-gamma and slow-gamma allows parallel processing of distinct aspects of vision and visual perception. The visual cortex slice provides a novel in vitro model to study cortical high-frequency gamma oscillations.

  20. A method to describe inelastic gamma field distribution in neutron gamma density logging.

    PubMed

    Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

    2017-11-01

    Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Influence of terrestrial radionuclides on environmental gamma exposure in a uranium deposit in Paraíba, Brazil.

    PubMed

    Araújo Dos Santos Júnior, José; Dos Santos Amaral, Romilton; Simões Cezar Menezes, Rômulo; Reinaldo Estevez Álvarez, Juan; Marques do Nascimento Santos, Josineide; Herrero Fernández, Zahily; Dias Bezerra, Jairo; Antônio da Silva, Alberto; Francys Rodrigues Damascena, Kennedy; de Almeida Maciel Neto, José

    2017-07-01

    One of the main natural uranium deposits in Brazil is located in the municipality of Espinharas, in the State of Paraíba. This area may present high levels of natural radioactivity due to the presence of these radionuclides. Since this is a populated area, there is need for a radioecological dosimetry assessment to investigate the possible risks to the population. Based on this problem, the objective of this study was to estimate the environmental effective dose outdoors in inhabited areas influenced by the uranium deposit, using the specific activities of equivalent uranium, equivalent thorium and 40 K and conversion factors. The environmental assessment was carried using gamma spectroscopy in sixty-two points within the municipality, with a high-resolution gamma spectrometer with HPGe semiconductor detector and Be window. The results obtained ranged from 0.01 to 19.11 mSv y -1 , with an average of 2.64 mSv y -1 . These levels are, on average, 23 times higher than UNSCEAR reference levels and up to 273 times the reference value of the earth's crust for primordial radionuclides. Therefore, given the high radioactivity levels found, we conclude that there is need for further investigation to evaluate the levels of radioactivity in indoor environments, which will reflect more closely the risks of the local population. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Neutron response of GafChromic® EBT2 film

    NASA Astrophysics Data System (ADS)

    Hsiao, Ming-Chen; Liu, Yuan-Hao; Chen, Wei-Lin; Jiang, Shiang-Huei

    2013-03-01

    Neutron and gamma-ray mixed field dosimetry remains one of the most challenging topics in radiation dosimetry studies. However, the requirement for accurate mixed field dosimetry is increasing because of the considerable interest in high-energy radiotherapy machines, medical ion beams and BNCT epithermal neutron beams. Therefore, this study investigated the GafChromic® EBT2 film. The linearity, reproducibility, energy dependence and homogeneity of the film were tested in a 60Co medical beam, 6-MV LINAC and 10-MV LINAC. The linearity and self-developing effect of the film irradiated in an epithermal neutron beam were also examined. These basic detector characteristics showed that EBT2 film can be effectively applied in mixed field dosimetry. A general detector response model was developed to determine the neutron relative effectiveness (RE) values. The RE value of fast neutrons varies with neutron spectra. By contrast, the RE value of thermal neutrons was determined as a constant; it is only 32.5% in relation to gamma rays. No synergy effect was observed in this study. The lithium-6 capture reaction dominates the neutron response in the thermal neutron energy range, and the recoil hydrogen dose becomes the dominant component in the fast neutron energy region. Based on this study, the application of the EBT2 film in the neutron and gamma-ray mixed field is feasible.

  3. PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT)

    NASA Astrophysics Data System (ADS)

    Ong, Yi Hong; Kim, Michele M.; Finlay, Jarod C.; Dimofte, Andreea; Singhal, Sunil; Glatstein, Eli; Cengel, Keith A.; Zhu, Timothy C.

    2018-01-01

    Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important dosimetry quantity for PDT. However, the detected photosensitizer fluorescence may be distorted by variations in the absorption and scattering of both excitation and fluorescence light in tissue. Therefore, correction of the measured fluorescence for distortion due to variable optical properties is required for absolute quantification of photosensitizer concentration. In this study, we have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and photosensitizer fluorescence data. We measured PDT dose at four sites in the pleural cavity during pleural PDT. We have determined an empirical optical property correction function using Monte Carlo simulations of fluorescence for a range of physiologically relevant tissue optical properties. Parameters of the optical property correction function for Photofrin fluorescence were determined experimentally using tissue-simulating phantoms. In vivo measurements of photosensitizer fluorescence showed negligible photobleaching of Photofrin during the PDT treatment, but large intra- and inter-patient heterogeneities of in vivo Photofrin concentration are observed. PDT doses delivered to 22 sites in the pleural cavity of 8 patients were different by 2.9 times intra-patient and 8.3 times inter-patient.

  4. Dosimetry of radium-223 and progeny

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

    Fisher, D.R.; Sgouros, G.

    Radium-223 is a short-lived (11.4 d) alpha emitter with potential applications in radioimmunotherapy of cancer. Radium-223 can be complexed and linked to protein delivery molecules for specific tumor-cell targeting. It decays through a cascade of short-lived alpha- and beta-emitting daughters with emission of about 28 MeV of energy through complete decay. The first three alpha particles are essentially instantaneous. Photons associated with Ra-223 and progeny provide the means for tumor and normal-organ imaging and dosimetry. Two beta particles provide additional therapeutic value. Radium-223 may be produced economically and in sufficient amounts for widescale application. Many aspects of the chemistry ofmore » carrier-free isotope preparation, complexation, and linkage to the antibody have been developed and are being tested. The radiation dosimetry of a Ra-223-labeled antibody shows favorable tumor to normal tissue dose ratios for therapy. The 11.4-d half-life of Ra-223 allows sufficient time for immunoconjugate preparation, administration, and tumor localization by carrier antibodies before significant radiological decay takes place. If 0.01 percent of a 37 MBq (1 mCi) injection deposits in a one gram tumor mass, and if the activity is retained with a typical effective half-time (75 h), the absorbed dose will be 163 mGy MBq{sup {minus}1} (600 rad mCi{sup {minus}1}) administered. 49 refs., 5 figs., 2 tabs.« less

  5. IMRT verification using a radiochromic/optical-CT dosimetry system

    NASA Astrophysics Data System (ADS)

    Oldham, Mark; Guo, Pengyi; Gluckman, Gary; Adamovics, John

    2006-12-01

    This work represents our first experiences relating to IMRT verification using a relatively new 3D dosimetry system consisting of a PRESAGETM dosimeter (Heuris Inc, Pharma LLC) and an optical-CT scanning system (OCTOPUSTM TM MGS Inc). This work builds in a step-wise manner on prior work in our lab.

  6. The gamma cycle.

    PubMed

    Fries, Pascal; Nikolić, Danko; Singer, Wolf

    2007-07-01

    Activated neuronal groups typically engage in rhythmic synchronization in the gamma-frequency range (30-100 Hz). Experimental and modeling studies demonstrate that each gamma cycle is framed by synchronized spiking of inhibitory interneurons. Here, we review evidence suggesting that the resulting rhythmic network inhibition interacts with excitatory input to pyramidal cells such that the more excited cells fire earlier in the gamma cycle. Thus, the amplitude of excitatory drive is recoded into phase values of discharges relative to the gamma cycle. This recoding enables transmission and read out of amplitude information within a single gamma cycle without requiring rate integration. Furthermore, variation of phase relations can be exploited to facilitate or inhibit exchange of information between oscillating cell assemblies. The gamma cycle could thus serve as a fundamental computational mechanism for the implementation of a temporal coding scheme that enables fast processing and flexible routing of activity, supporting fast selection and binding of distributed responses. This review is part of the INMED/TINS special issue Physiogenic and pathogenic oscillations: the beauty and the beast, based on presentations at the annual INMED/TINS symposium (http://inmednet.com).

  7. Progress In The Development Of A Tomographic SPECT System For Online Dosimetry In BNCT

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

    Minsky, D. M.; Kreiner, A. J.; ECyT, UNSAM, M. de Irigoyen 3100

    2010-08-04

    In boron neutron capture therapy (BNCT) the delivered dose to the patient depends both on the neutron beam characteristics and on the {sup 10}B body distribution which, in turn, is governed by the tumor specificity of the {sup 10}B drug-carrier. BNCT dosimetry is a complex matter due to the several interactions that neutrons can undergo with the different nuclei present in tissue. However the boron capture reaction {sup 10}B(n,{alpha}){sup 7}Li accounts for about 80 % of the total dose in a tumor with 40 ppm in {sup 10}B concentration. Present dosimetric methods are indirect, based on drug biodistribution statistical datamore » and subjected to inter and intra-patient variability. In order to overcome the consequences of the concomitant high dosimetric uncertainties, we propose a SPECT (Single Photon Emission Tomography) approach based on the detection of the prompt gamma-ray (478 keV) emitted in 94 % of the cases from {sup 7}Li. For this purpose we designed, built and tested a prototype based on LaBr{sub 3}(Ce) scintillators. Measurements on a head and tumor phantom were performed in the accelerator-based BNCT facility of the University of Birmingham (UK). They result in the first tomographic image of the 10B capture distribution obtained in a BNCT facility.« less

  8. The stability of liquid-filled matrix ionization chamber electronic portal imaging devices for dosimetry purposes.

    PubMed

    Louwe, R J W; Tielenburg, R; van Ingen, K M; Mijnheer, B J; van Herk, M B

    2004-04-01

    This study was performed to determine the stability of liquid-filled matrix ionization chamber (LiFi-type) electronic portal imaging devices (EPID) for dosimetric purposes. The short- and long-term stability of the response was investigated, as well as the importance of factors influencing the response (e.g., temperature fluctuations, radiation damage, and the performance of the electronic hardware). It was shown that testing the performance of the electronic hardware as well as the short-term stability of the imagers may reveal the cause of a poor long-term stability of the imager response. In addition, the short-term stability was measured to verify the validity of the fitted dose-response curve immediately after beam startup. The long-term stability of these imagers could be considerably improved by correcting for room temperature fluctuations and gradual changes in response due to radiation damage. As a result, the reproducibility was better than 1% (1 SD) over a period of two years. The results of this study were used to formulate recommendations for a quality control program for portal dosimetry. The effect of such a program was assessed by comparing the results of portal dosimetry and in vivo dosimetry using diodes during the treatment of 31 prostate patients. The improvement of the results for portal dosimetry was consistent with the deviations observed with the reproducibility tests in that particular period. After a correction for the variation in response of the imager, the average difference between the measured and prescribed dose during the treatment of prostate patients was -0.7%+/-1.5% (1 SD), and -0.6%+/-1.1% (1 SD) for EPID and diode in vivo dosimetry, respectively. It can be concluded that a high stability of the response can be achieved for this type of EPID by applying a rigorous quality control program.

  9. A Platinum-Enriched gamma+gamma' Two-Phase Bond Coat on Ni-Base Superalloys

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

    Zhang, Ying; Pint, Bruce A; Haynes, James A

    2005-01-01

    Pt-enriched {gamma} + {gamma}{prime} two-phase coating was applied to directionally-solidified Ni-based superalloy Ren{acute e} 142 substrates with three different Hf levels (0.02, 0.76, and 1.37 wt.%). The coating was prepared by electroplating a thin layer of Pt on the superalloy followed by a diffusion treatment. The as-deposited coating exhibited a {gamma} + {gamma}{prime} two-phase microstructure with a major composition of Ni-16Al-18Pt-7Cr-9Co (in at.%) along with some incorporation of refractory elements from the substrates. Cyclic oxidation testing at 1100 C in air indicated improved oxidation resistance of the Ren{acute e} 142 alloys with the Pt-enriched {gamma} + {gamma}{prime} coatings. In addition,more » the oxidation resistance of both uncoated and coated alloys was proportional to the Hf content in the substrate. Compared with the single-phase {beta}-(Ni,Pt)Al coating, slightly higher mass gains and localized spallation were observed on the {gamma} + {gamma}{prime} two-phase coating, which might be due to the segregation of refractory elements and high sulfur levels in these superalloy substrates.« less

  10. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

    The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

  11. Expression of peroxisome proliferator-activated receptor gamma (PPAR-gamma) in canine nasal carcinomas.

    PubMed

    Paciello, O; Borzacchiello, G; Varricchio, E; Papparella, S

    2007-10-01

    Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is a ligand-activated transcriptional factor belonging to the steroid receptor superfamily. PPAR-gamma is expressed in multiple normal and neoplastic tissues, such as the breast, colon, lung, ovary and placenta. In addition to adipogenic and anti-inflammatory effects, PPAR-gamma activation has been shown to be anti-proliferative by its differentiation-promoting effect, suggesting that activation of PPAR-gamma may be useful in slowing or arresting the proliferation of de-differentiated tumour cells. In this study, we investigated the expression of PPAR-gamma in normal and neoplastic canine nasal epithelium. Twenty-five samples composed of five normal nasal epithelia and 20 canine nasal carcinomas, were immunohistochemically stained for PPAR-gamma. The specificity of the antibody was verified by Western Blot analysis. Confocal laser scanning microscopical investigation was also performed. In normal epithelium, the staining pattern was cytoplasmic and polarized at the cellular free edge. In carcinomas, the neoplastic cells showed mainly strong cytoplasmatic PPAR-gamma expression; moreover, perinuclear immunoreactivity was also detected and few neoplastic cells exhibited a nuclear positivity. Our results demonstrate different patterns of PPAR-gamma expression in normal canine nasal epithelium when compared with canine nasal carcinoma. The importance of this transcription factor in the pathophysiology of several different tumours has stimulated much research in this field and has opened new opportunities for the treatment of the tumours.

  12. On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Andreo, Pedro; Burns, David T.; Salvat, Francesc

    2012-04-01

    . 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (µen/ρ)graphite,air for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication).

  13. Implementation of IMRT and VMAT using Delta4 phantom and portal dosimetry as dosimetry verification tools

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

    Daci, Lulzime, E-mail: lulzime.daci@nodlandssykehuset.no; Malkaj, Partizan, E-mail: malkaj-p@hotmail.com

    2016-03-25

    In this study we analyzed and compared the dose distribution of different IMRT and VMAT plans with the intent to provide pre-treatment quality assurance using two different tools. Materials/Methods: We have used the electronic portal imaging device EPID after calibration to dose and correction for the background offset signal and also the Delta4 phantom after en evaluation of angular sensitivity. The Delta4 phantom has a two-dimensional array with ionization chambers. We analyzed three plans for each anatomical site calculated by Eclipse treatment planning system. The measurements were analyzed using γ-evaluation method with passing criteria 3% absolute dose and 3 mm distancemore » to agreement (DTA). For all the plans the range of score has been from 97% to 99% for gantry fixed at 0° while for rotational planes there was a slightly decreased pass rates and above 95%. Point measurement with a ionization chamber were done in additional to see the accuracy of portal dosimetry and to evaluate the Delta4 device to various dose rates. Conclusions: Both Delt4 and Portal dosimetry shows good results between the measured and calculated doses. While Delta4 is more accurate in measurements EPID is more time efficient. We have decided to use both methods in the first steps of IMRT and VMAT implementation and later on to decide which of the tools to use depending on the complexity of plans, how much accurate we want to be and the time we have on the machine.« less

  14. Thermoluminescence of nanocrystalline CaSO{sub 4}: Dy for gamma dosimetry and calculation of trapping parameters using deconvolution method

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

    Mandlik, Nandkumar, E-mail: ntmandlik@gmail.com; Patil, B. J.; Bhoraskar, V. N.

    2014-04-24

    Nanorods of CaSO{sub 4}: Dy having diameter 20 nm and length 200 nm have been synthesized by the chemical coprecipitation method. These samples were irradiated with gamma radiation for the dose varying from 0.1 Gy to 50 kGy and their TL characteristics have been studied. TL dose response shows a linear behavior up to 5 kGy and further saturates with increase in the dose. A Computerized Glow Curve Deconvolution (CGCD) program was used for the analysis of TL glow curves. Trapping parameters for various peaks have been calculated by using CGCD program.

  15. Fading Correction To Be Used In Clinical Thermoluminescence Dosimetry

    NASA Astrophysics Data System (ADS)

    Furetta, C.; Azorin, J.; Rivera, T.

    2004-09-01

    This paper presents some useful expressions for fading correction, which can be used in practical situations as they can be encountered in clinical dosimetry. The situations took into consideration can be encountered in hospital environments during and after radiotherapeutic treatments of patients as well as for radiation protection procedures concerning staff members.

  16. Cloning, sequencing and expression of white rhinoceros (Ceratotherium simum) interferon-gamma (IFN-gamma) and the production of rhinoceros IFN-gamma specific antibodies.

    PubMed

    Morar, D; Tijhaar, E; Negrea, A; Hendriks, J; van Haarlem, D; Godfroid, J; Michel, A L; Rutten, V P M G

    2007-01-15

    Bovine tuberculosis (BTB) is endemic in African buffalo (Syncerus caffer) in the Kruger National Park (KNP). In addition to buffalo, Mycobacterium bovis has been found in at least 14 other mammalian species in South Africa, including kudu (Tragelaphus strepsiceros), Chacma baboon (Papio ursinus) and lion (Panthera leo). This has raised concern about the spillover into other potentially susceptible species like rhinoceros, thus jeopardising breeding and relocation projects aiming at the conservation of biodiversity. Hence, procedures to screen for and diagnose BTB in black rhinoceros (Diceros bicornis) and white rhinoceros (Ceratotherium simum) need to be in place. The Interferon-gamma (IFN-gamma) assay is used as a routine diagnostic tool to determine infection of cattle and recently African buffalo, with M. bovis and other mycobacteria. The aim of the present work was to develop reagents to set up a rhinoceros IFN-gamma (RhIFN-gamma) assay. The white rhinoceros IFN-gamma gene was cloned, sequenced and expressed as a mature protein. Amino acid (aa) sequence analysis revealed that RhIFN-gamma shares a homology of 90% with equine IFN-gamma. Monoclonal antibodies, as well as polyclonal chicken antibodies (Yolk Immunoglobulin-IgY) with specificity for recombinant RhIFN-gamma were produced. Using the monoclonals as capture antibodies and the polyclonal IgY for detection, it was shown that recombinant as well as native white rhinoceros IFN-gamma was recognised. This preliminary IFN-gamma enzyme-linked immunosorbent assay (ELISA), has the potential to be developed into a diagnostic assay for M. bovis infection in rhinoceros.

  17. Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

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

    Tanyi, James A.; Nitzling, Kevin D.; Lodwick, Camille J.

    2011-02-15

    Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation {+-}0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibilitymore » of the system was {+-}0.55% for dose fractions of {approx}100 cGy. Energy dependence was within {+-}1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R{sup 2}=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within {+-}0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.« less

  18. Measurements of the $$\\mathrm{ pp \\to W \\gamma\\gamma }$$ and $$\\mathrm{ pp \\to Z \\gamma\\gamma }$$ cross sections and limits on anomalous quartic gauge couplings at $$\\sqrt{s} =$$ 8 TeV

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

    Sirunyan, A. M.; Tumasyan, A.; Adam, W.

    Here, measurements are presented ofmore » $$ \\mathrm{ W \\gamma\\gamma } $$ and $$ \\mathrm{ Z \\gamma\\gamma } $$ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$$^{-1}$$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $$\\mathrm{ W } \\to \\ell\

  19. Measurements of the $$\\mathrm{ pp \\to W \\gamma\\gamma }$$ and $$\\mathrm{ pp \\to Z \\gamma\\gamma }$$ cross sections and limits on anomalous quartic gauge couplings at $$\\sqrt{s} =$$ 8 TeV

    DOE PAGES

    Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

    2017-10-11

    Here, measurements are presented ofmore » $$ \\mathrm{ W \\gamma\\gamma } $$ and $$ \\mathrm{ Z \\gamma\\gamma } $$ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$$^{-1}$$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $$\\mathrm{ W } \\to \\ell\

  20. Self-expanding stent effects on radiation dosimetry in esophageal cancer.

    PubMed

    Francis, Samual R; Anker, Christopher J; Wang, Brian; Williams, Greg V; Cox, Kristen; Adler, Douglas G; Shrieve, Dennis C; Salter, Bill J

    2013-07-08

    It is the purpose of this study to evaluate how self-expanding stents (SESs) affect esophageal cancer radiation planning target volumes (PTVs) and dose delivered to surrounding organs at risk (OARs). Ten patients were evaluated, for whom a SES was placed before radiation. A computed tomography (CT) scan obtained before stent placement was fused to the post-stent CT simulation scan. Three methods were used to represent pre-stent PTVs: 1) image fusion (IF), 2) volume approximation (VA), and 3) diameter approximation (DA). PTVs and OARs were contoured per RTOG 1010 protocol using Eclipse Treatment Planning software. Post-stent dosimetry for each patient was compared to approximated pre-stent dosimetry. For each of the three pre-stent approximations (IF, VA, and DA), the mean lung and liver doses and the estimated percentages of lung volumes receiving 5 Gy, 10 Gy, 20 Gy, and 30 Gy, and heart volumes receiving 40 Gy were significantly lower (p-values < 0.02) than those estimated in the post-stent treatment plans. The lung V5, lung V10, and heart V40 constraints were achieved more often using our pre-stent approximations. Esophageal SES placement increases the dose delivered to the lungs, heart, and liver. This may have clinical importance, especially when the dose-volume constraints are near the recommended thresholds, as was the case for lung V5, lung V10, and heart V40. While stents have established benefits for treating patients with significant dysphagia, physicians considering stent placement and radiation therapy must realize the effects stents can have on the dosimetry.