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Sample records for 192ir brachytherapy source

  1. In vivo dosimetry thermoluminescence dosimeters during brachytherapy with a 370 GBq {sup 192}Ir source

    Cuepers, S.; Piessens, M.; Verbeke, L.; Roelstraete, A. [Onze-Lieve-Vrouw Hospitaal, Aalst (Belgium). Dept. of Radiotherapy and Oncology

    1995-12-01

    When using LiF thermoluminescence dosimeters in brachytherapy, we have to take into account the properties of a high dose rate {sup 192}Ir source (energy spectrum ranging form 9 to 885 keV, steep dose gradient in the vicinity of the source) and these of the dosimeters themselves (supralinearity, reproducibility, size). All these characteristics combine into a set of correction factors which have been determined during in phantom measurements. These results have then been used to measure the dose delivered to organs at risk (e.g. rectum, bladder, etc.) during high dose rate brachytherapy with a 370 GBq {sup 192}Ir source for patients with gynaecological tumors.

  2. Audit on source strength determination for HDR and PDR 192Ir brachytherapy in Sweden

    Background and purpose: To investigate the status of source strength determination in terms of reference air kerma rate (RAKR) for HDR and PDR 192Ir brachytherapy in Sweden. Materials and methods: RAKR was determined in each of the 14 Swedish afterloaders, using calibrated equipment from the Swedish Secondary Standard Dosimetry Laboratory. Results: Values of RAKR from the external audit, the hospitals and vendors agreed within the uncertainty limits guaranteed by the vendors. Conclusions: The accuracy in RAKR determination has increased over the last years as a result of increased availability of interpolation standards for HDR 192Ir and the increased use of robust well-type ion chambers designed for brachytherapy. It is recommended to establish a ratio between the RAKR value from own measurements at the hospital and that of the vendor since such a ratio embeds constant systematic differences due to e.g. varying traceability and therefore has the potential of being less uncertain than the RAKR alone. Traceability to primary standards for HDR 192Ir sources will in the future significantly decrease the uncertainty in RAKR of 192Ir brachytherapy

  3. Enhancement and validation of Geant4 Brachytherapy application on clinical HDR 192Ir source

    The Geant4 Monte Carlo MC associated Brachytherapy example was adapted, enhanced and several analysis techniques have been developed. The simulation studies the isodose distribution of the total, primary and scattered doses around a Nucletron microSelectron 192Ir source. Different phantom materials were used (water, tissue and bone) and the calculation was conducted at various depths and planes. The work provides an early estimate of the required number of primary events to ultimately achieve a given uncertainty at a given distance, in the otherwise CPU and time consuming clinical MC calculation. The adaptation of the Geant4 toolkit and the enhancements introduced to the code are all validated including the comprehensive decay of the 192Ir source, the materials used to build the geometry, the geometry itself and the calculated scatter to primary dose ratio. The simulation quantitatively illustrates that the scattered dose in the bone medium is larger than its value in water and tissue. As the distance away from the source increases, scatter contribution to dose becomes more significant as the primary dose decreases. The developed code could be viewed as a platform that contains detailed dose calculation model for clinical application of HDR 192Ir in Brachytherapy. - Highlights: • We enhanced and validated the Geant4 associated Brachytherapy code. • Primary and scattered doses from an actual 192Ir source are separated. • Different phantom materials are investigated. • The number of primary events to achieve a given uncertainty is provided. • A platform for detailed dose for clinical HDR Brachytherapy is established

  4. Dosimetry experience of 192IR sources used In HDR brachytherapy for cervical cancer

    Purpose/Objective: The 192IR Sources are the most commonly used in radiotherapy treatments HDR worldwide. According to international recommendations on quality assurance in HDR brachytherapy, an acceptance test based on the determination of the source strength of any new source shall be carried out before first application to verify the manufacturer’s calibration data. The present paper gives the experimental determination of the source strength for our brachytherapy sources used until now in brachytherapy treatments. Materials/Methods: At Mother Teresa University Hospital we have a cost-effective gynecological brachytherapy unit from Eckert & Ziegler BEBIG named GyneSource® that is a five channel HDR after loader equipped with an 192IR source. The software used is HDR plus™ 2.5 that delivers an optimized treatment plan and makes the process especially fast and we use intracavitary BEBIG applicators. From April 2009 up to December 2012, we have imported nine HDR 192IR Sources. The exchange of the source and acceptance test is done by the physicist of the clinic once the source is imported. The measurements are done with a Well-type ionization chamber HDR1000 Plus and the electrometer used is MAX4000. Only seven sources are compared as we miss the dosimetry data of the first source, and the forth source was not measured and not used because the machine was not working in that time. Results/Conclusions: Eight sources were accepted for clinically use as the measurement were within the tolerance. The source number four with e deviation of -1.92% has been double checked compared with a free in-air measurement with farmer type chamber that gave a deviation to source certificate of 4% that is still inside the tolerance to accept a source for clinical use. The deviations of measured Air Kerma rate to the value of the sources certificates of all our used 192IR sources are less than 2%, which are within the tolerance. The checked value of updated source strength in

  5. Dosimetry audit on the accuracy of 192Ir brachytherapy source strength determinations in Sweden

    The absorbed dose delivered to the patient in brachytherapy is directly proportional to the source strength in terms of the reference air-kerma rate (RAKR). Verification of this quantity by the hospitals is widely recognized as an important part of a quality assurance program. An external audit was performed on behalf of the Secondary Standard Dosimetry Laboratory at the Swedish Radiation Protection Authority (SSI). The aim was to investigate how accurately the source-strength in 192Ir brachytherapy is determined at Swedish hospitals. The SSI reference well-type ion chamber and calibrated equipment were used to measure the RAKR of an 192Ir source in each of the 14 Swedish afterloading units. Comparisons with values determined by vendors and hospitals were made. Agreement in values of RAKR as determined by SSI, hospitals and vendors were in all cases within the ±3% uncertainty (at a coverage factor of k=2), typically guaranteed by the vendors. The good agreement reflects the robustness and easy handling of well-type chambers designed for brachytherapy in use by all Swedish hospitals. The 192Ir calibration service planned at SSI will solve the hospitals current problem with recalibration of equipment. SSI can also advise hospitals to follow the IAEA recommendations for measurement techniques and maintenance of equipment. It is worthwhile for the hospitals to establish their own ratio (or deviation) with the vendor and follow it as function of time. Such a mean-ratio embeds systematic differences of various origins and have a lower uncertainty than has the RAKR alone, making it useful for early detection of problems with equipment or routines. SSI could also define requirements for the agreement between source strengths as determined by hospitals and vendors and couple this to an action plan, dependent on level of disagreement, and some kind of reporting to SSI

  6. Verification of high dose rate 192Ir source position during brachytherapy treatment

    A system for in vivo tracking of 1 Ci 192Ir source during brachytherapy treatment has been built using high resistivity silicon pad detectors as image sensors and knife-edge lead pinholes as collimators. The sensors consist of 256 pads arranged in 32 x8 grid with pad size 1.4x1.4mm2 and 1 mm thickness. The sensors have two metal layers, enabling connection of readout electronics (VATAGP31 chips) at the edge of the detector. With source self-images obtained from a dual-pinhole system, location of the source can be reconstructed in three dimensions in real time, allowing on-line detection of deviations from planned treatment. The system was tested with 1 Ci 192Ir clinical source in air and plexi-glass phantom. The movements of the source could be tracked in a field of view of approximately 20x20x20cm3 with absolute precision of about 5 mm. Positions of the source, relative to the first measured source position, could be mapped with precision of around 3 mm.

  7. Monte Carlo angular dose distribution of the microselectron HDR 192Ir brachytherapy source

    Polar dose profiles around the Nucletron MicroSelectron high dose rate (HDR) 192Ir brachytherapy source were calculated using the Monte Carlo radiation transport code MCNP (Monte Carlo N Particle) version 4A. The geometry modeled consisted of an identical simulation of the construction of the MicroSelectron HDR source located at the centre of a spherical water phantom of 100cm radius. Doses were calculated using a spherical coordinate system at 5 degree intervals (measured relative to the cable) at radii of 0.25, 0.5,1.0, 3.0, 5.0 and 7.0cm. These polar doses were compared to equivalent profiles from the Nucletron PLATO Brachytherapy Planning System (BPS) version 13.X. At 3.0, 5.0 and 7.0cm radii, the Monte Carlo and BPS profiles are generally within 3%. The near field polar dose profiles however, are in significant disagreement. At 1.0cm radius, the discrepancy can exceed 5%. At 0.5cm this figure rises to 15%, and even 60% at 0.25cm radius

  8. Comparison of calibration procedures for 192Ir high-dose-rate brachytherapy sources

    Purpose: To compare the efficacy of different calibration procedures for 192Ir high-dose-rate (HDR) brachytherapy sources and to determine their suitability in clinical practice. In addition the manufacturer's calibration is compared with our experimental measurements so that the accuracy of the source strength on the manufacturer certificate which is supplied with each new 192Ir source can be accessed. Methods and Materials: We compared three types of calibration system: well-type chambers (HDR-1000 and SDS), cylindrical phantom, and plate phantom. The total number of measurements we obtained was 365. The number of sources used for the calibration procedure comparison was 20 and the number used for comparison with the manufacturer's calibration was 46. This study was made during the period 1989-1997. Also, Physikalisch-Technische Bundesanstalt (PTB) calibrated one of our sources using their PTB protocol so that the results could be compared with our own. Results: The sensitivity of each system on scattering from the room walls was studied. It was found that different minimum lateral distances from the walls were required for the different systems tested: 15 cm and 25 cm for the well-type chambers, 75 cm for the cylindrical phantom, and 13 cm for the plate phantom. The minimum thickness required to reach phantom scattering saturation for the plate phantom setup is 24 cm. The influence of the applicator material used in the calibration setup was found to be 1.7% for the stainless steel dosimetry applicator compared to the plastic 5F applicator. The accuracy of source positioning within the applicator can lead to dosimetric errors of ±1.2% for the radial distance of 8.0 cm used with both solid phantoms. The change in the response for both well-type chambers was only 0.1% for changes in the source position within ±7.5 mm around the response peak. Good agreement was found between all dosimetry systems included in our study. Taking the HDR-1000 well-type chamber

  9. Calibration of a 192Ir source for high dose brachytherapy using various techniques

    In this research we studied three experimental procedures for calibration of a source of 192Ir to high dose rate for clinical brachytherapy use, and thus were compared and analysis of the advantages and disadvantages of each. For this study we quantified the value of the current kerma rate reference in air by three procedures: source calibration using a well chamber, with an cylindrical ionization chamber in air, and a cylindrical ionization chamber on a phantom, and this magnitude was compared with the value provided by the manufacturer of the source and thereby obtaining the deviation corresponding . Thus, it was found that the deviation corresponding to the source calibration making use of a well chamber, remained within tolerance, while the cylindrical ionization chamber in air and on phantom exceeded the standards established in some documents. However, although both the measurement in air and in the phantom are the procedures for the final calibration source, these can be used to verify that the delivered dose are in tolerance.

  10. Dosimetric study of a brachytherapy treatment of esophagus with Brazilian 192Ir sources using an anthropomorphic phantom

    Several radioisotopes are produced at Instituto de Pesquisas Energéticas e Nucleares for the use in medical treatments, including the activation of 192Ir sources. These sources are suitable for brachytherapy treatments, due to their low or high activity, depending on the concentration of 192Ir, easiness to manufacture, small size, stable daughter products and the possibility of re-utilization. They may be used for the treatment of prostate, cervix, head and neck, skin, breast, gallbladder, uterus, vagina, lung, rectum, and eye cancer treatment. In this work, the use of some 192Ir sources was studied for the treatment of esophagus cancer, especially the dose determination of important structures, such as those on the mediastinum. This was carried out utilizing a FASH anthropomorphic phantom and the MCNP5 Monte Carlo code to transport the radiation through matter. It was possible to observe that the doses at lungs, breast, esophagus, thyroid and heart were the highest, which was expected due to their proximity to the source. Therefore, the data are useful to assess the representative dose specific to brachytherapy treatments on the esophagus for radiation protection purposes. - Author-Highlights: • The use of brachytherapy sources was studied for the treatment of esophagus cancer. • FASH anthropomorphic phantom and MCNP5 Monte Carlo code were employed. • The doses at lungs, breast, esophagus, thyroid and heart were the highest. • The data is useful to assess the representative doses of treatments on the esophagus

  11. Estimation of distance error by fuzzy set theory required for strength determination of HDR 192Ir brachytherapy sources

    Verification of the strength of high dose rate (HDR) 192Ir brachytherapy sources on receipt from the vendor is an important component of institutional quality assurance program. Either reference air-kerma rate (RAKR) or air-kerma strength (AKS) is the recommended quantity to specify the strength of gamma-emitting brachytherapy sources. The use of Farmer-type cylindrical ionization chamber of sensitive volume 0.6 cm3 is one of the recommended methods for measuring RAKR of HDR 192Ir brachytherapy sources. While using the cylindrical chamber method, it is required to determine the positioning error of the ionization chamber with respect to the source which is called the distance error. An attempt has been made to apply the fuzzy set theory to estimate the subjective uncertainty associated with the distance error. A simplified approach of applying this fuzzy set theory has been proposed in the quantification of uncertainty associated with the distance error. In order to express the uncertainty in the framework of fuzzy sets, the uncertainty index was estimated and was found to be within 2.5%, which further indicates that the possibility of error in measuring such distance may be of this order. It is observed that the relative distance li estimated by analytical method and fuzzy set theoretic approach are consistent with each other. The crisp values of li estimated using analytical method lie within the bounds computed using fuzzy set theory. This indicates that li values estimated using analytical methods are within 2.5% uncertainty. This value of uncertainty in distance measurement should be incorporated in the uncertainty budget, while estimating the expanded uncertainty in HDR 192Ir source strength measurement. (author)

  12. Estimation of distance error by fuzzy set theory required for strength determination of HDR (192)Ir brachytherapy sources.

    Kumar, Sudhir; Datta, D; Sharma, S D; Chourasiya, G; Babu, D A R; Sharma, D N

    2014-04-01

    Verification of the strength of high dose rate (HDR) (192)Ir brachytherapy sources on receipt from the vendor is an important component of institutional quality assurance program. Either reference air-kerma rate (RAKR) or air-kerma strength (AKS) is the recommended quantity to specify the strength of gamma-emitting brachytherapy sources. The use of Farmer-type cylindrical ionization chamber of sensitive volume 0.6 cm(3) is one of the recommended methods for measuring RAKR of HDR (192)Ir brachytherapy sources. While using the cylindrical chamber method, it is required to determine the positioning error of the ionization chamber with respect to the source which is called the distance error. An attempt has been made to apply the fuzzy set theory to estimate the subjective uncertainty associated with the distance error. A simplified approach of applying this fuzzy set theory has been proposed in the quantification of uncertainty associated with the distance error. In order to express the uncertainty in the framework of fuzzy sets, the uncertainty index was estimated and was found to be within 2.5%, which further indicates that the possibility of error in measuring such distance may be of this order. It is observed that the relative distance li estimated by analytical method and fuzzy set theoretic approach are consistent with each other. The crisp values of li estimated using analytical method lie within the bounds computed using fuzzy set theory. This indicates that li values estimated using analytical methods are within 2.5% uncertainty. This value of uncertainty in distance measurement should be incorporated in the uncertainty budget, while estimating the expanded uncertainty in HDR (192)Ir source strength measurement. PMID:24872605

  13. Estimation of distance error by fuzzy set theory required for strength determination of HDR 192Ir brachytherapy sources

    Kumar, Sudhir; Datta, D.; Sharma, S. D.; Chourasiya, G.; Babu, D. A. R.; Sharma, D. N.

    2014-01-01

    Verification of the strength of high dose rate (HDR) 192Ir brachytherapy sources on receipt from the vendor is an important component of institutional quality assurance program. Either reference air-kerma rate (RAKR) or air-kerma strength (AKS) is the recommended quantity to specify the strength of gamma-emitting brachytherapy sources. The use of Farmer-type cylindrical ionization chamber of sensitive volume 0.6 cm3 is one of the recommended methods for measuring RAKR of HDR 192Ir brachytherapy sources. While using the cylindrical chamber method, it is required to determine the positioning error of the ionization chamber with respect to the source which is called the distance error. An attempt has been made to apply the fuzzy set theory to estimate the subjective uncertainty associated with the distance error. A simplified approach of applying this fuzzy set theory has been proposed in the quantification of uncertainty associated with the distance error. In order to express the uncertainty in the framework of fuzzy sets, the uncertainty index was estimated and was found to be within 2.5%, which further indicates that the possibility of error in measuring such distance may be of this order. It is observed that the relative distance li estimated by analytical method and fuzzy set theoretic approach are consistent with each other. The crisp values of li estimated using analytical method lie within the bounds computed using fuzzy set theory. This indicates that li values estimated using analytical methods are within 2.5% uncertainty. This value of uncertainty in distance measurement should be incorporated in the uncertainty budget, while estimating the expanded uncertainty in HDR 192Ir source strength measurement. PMID:24872605

  14. Microdosimetric evaluation of relative biological effectiveness for 103PD, 125I, 241AM, and 192IR brachytherapy sources

    Purpose: To determine the microdosimetric-derived relative biological effectiveness (RBE) of 103Pd, 125I, 241Am, and 192Ir brachytherapy sources at low doses and/or low dose rates. Methods and Materials: The Theory of Dual Radiation Action can be used to predict expected RBE values based on the spatial distribution of energy deposition at microscopic levels from these sources. Single-event lineal energy spectra for these isotopes have been obtained both experimentally and theoretically. A grid-defined wall-less proportional counter was used to measure the lineal energy distributions. Unlike conventional Rossi proportional counters, the counter used in these measurements has a conducting nylon fiber as the central collecting anode and has no metal parts. Thus, the Z-dependence of the photoelectric effect is eliminated as a source of measurement error. Single-event spectra for these brachytherapy sources have been also calculated by: (a) the Monte Carlo code MCNP to generate the electron slowing down spectrum, (b) transport of monoenergetic electron tracks, event by event, with our Monte Carlo code DELTA, (c) using the concept of associated volume to obtain the lineal energy distribution f(y) for each monoenergetic electron, and (d) obtaining the composite lineal energy spectrum for a given brachytherapy source based on the electron spectrum calculated at step (a). Results: Relative to 60Co, the RBE values obtained from this study are: 2.3 for 103Pd, 2.1 for 125I, 2.1 for 241Am, and 1.3 for 192Ir. Conclusions: These values are consistent with available data from in vitro cell survival experiments. We suggest that, at least for these brachytherapy sources, microdosimetry may be used as a credible alternative to time-consuming (and often uncertain) radiobiological experiments to obtain information on radition quality and make reliable predictions of RBE in low dose rate brachytherapy

  15. On source models for (192)Ir HDR brachytherapy dosimetry using model based algorithms.

    Pantelis, Evaggelos; Zourari, Kyveli; Zoros, Emmanouil; Lahanas, Vasileios; Karaiskos, Pantelis; Papagiannis, Panagiotis

    2016-06-01

    A source model is a prerequisite of all model based dose calculation algorithms. Besides direct simulation, the use of pre-calculated phase space files (phsp source models) and parameterized phsp source models has been proposed for Monte Carlo (MC) to promote efficiency and ease of implementation in obtaining photon energy, position and direction. In this work, a phsp file for a generic (192)Ir source design (Ballester et al 2015) is obtained from MC simulation. This is used to configure a parameterized phsp source model comprising appropriate probability density functions (PDFs) and a sampling procedure. According to phsp data analysis 15.6% of the generated photons are absorbed within the source, and 90.4% of the emergent photons are primary. The PDFs for sampling photon energy and direction relative to the source long axis, depend on the position of photon emergence. Photons emerge mainly from the cylindrical source surface with a constant probability over  ±0.1 cm from the center of the 0.35 cm long source core, and only 1.7% and 0.2% emerge from the source tip and drive wire, respectively. Based on these findings, an analytical parameterized source model is prepared for the calculation of the PDFs from data of source geometry and materials, without the need for a phsp file. The PDFs from the analytical parameterized source model are in close agreement with those employed in the parameterized phsp source model. This agreement prompted the proposal of a purely analytical source model based on isotropic emission of photons generated homogeneously within the source core with energy sampled from the (192)Ir spectrum, and the assignment of a weight according to attenuation within the source. Comparison of single source dosimetry data obtained from detailed MC simulation and the proposed analytical source model show agreement better than 2% except for points lying close to the source longitudinal axis. PMID:27191179

  16. On source models for 192Ir HDR brachytherapy dosimetry using model based algorithms

    Pantelis, Evaggelos; Zourari, Kyveli; Zoros, Emmanouil; Lahanas, Vasileios; Karaiskos, Pantelis; Papagiannis, Panagiotis

    2016-06-01

    A source model is a prerequisite of all model based dose calculation algorithms. Besides direct simulation, the use of pre-calculated phase space files (phsp source models) and parameterized phsp source models has been proposed for Monte Carlo (MC) to promote efficiency and ease of implementation in obtaining photon energy, position and direction. In this work, a phsp file for a generic 192Ir source design (Ballester et al 2015) is obtained from MC simulation. This is used to configure a parameterized phsp source model comprising appropriate probability density functions (PDFs) and a sampling procedure. According to phsp data analysis 15.6% of the generated photons are absorbed within the source, and 90.4% of the emergent photons are primary. The PDFs for sampling photon energy and direction relative to the source long axis, depend on the position of photon emergence. Photons emerge mainly from the cylindrical source surface with a constant probability over  ±0.1 cm from the center of the 0.35 cm long source core, and only 1.7% and 0.2% emerge from the source tip and drive wire, respectively. Based on these findings, an analytical parameterized source model is prepared for the calculation of the PDFs from data of source geometry and materials, without the need for a phsp file. The PDFs from the analytical parameterized source model are in close agreement with those employed in the parameterized phsp source model. This agreement prompted the proposal of a purely analytical source model based on isotropic emission of photons generated homogeneously within the source core with energy sampled from the 192Ir spectrum, and the assignment of a weight according to attenuation within the source. Comparison of single source dosimetry data obtained from detailed MC simulation and the proposed analytical source model show agreement better than 2% except for points lying close to the source longitudinal axis.

  17. Investigation of Dosimetric Parameters of $^{192}$Ir MicroSelectron v2 HDR Brachytherapy Source Using EGSnrc Monte Carlo Code

    Naeem, Hamza; Zheng, Huaqing; Cao, Ruifen; Pei, Xi; Hu, Liqin; Wu, Yican

    2016-01-01

    The $^{192}$Ir sources are widely used for high dose rate (HDR) brachytherapy treatments. The aim of this study is to simulate $^{192}$Ir MicroSelectron v2 HDR brachytherapy source and calculate the air kerma strength, dose rate constant, radial dose function and anisotropy function established in the updated AAPM Task Group 43 protocol. The EGSnrc Monte Carlo (MC) code package is used to calculate these dosimetric parameters, including dose contribution from secondary electron source and also contribution of bremsstrahlung photons to air kerma strength. The Air kerma strength, dose rate constant and radial dose function while anisotropy functions for the distance greater than 0.5 cm away from the source center are in good agreement with previous published studies. Obtained value from MC simulation for air kerma strength is $9.762\\times 10^{-8} \\textrm{UBq}^{-1}$and dose rate constant is $1.108\\pm 0.13\\%\\textrm{cGyh}^{-1} \\textrm{U}^{-1}$.

  18. The history of brachytherapy in Russia: comparison of 60Co vs. 192Ir sources

    Brachytherapy is known as the first historical method of radiotherapy. At the beginning of its development it was used only as manual applications of liquid solutions of nuclides. Only from the middle of 1950-th specialized machines for automatic afterloading have been designed. The first types of the machines were those with pneumatically driven pellets of 137Cs. The main advantage of this nuclide is its long half-life time of about 30 years resulting in long periods between source replacements. But due to the same reason, it is impossible to provide high source activity within small pellets. So those machines can be defined as those of low dose rate (less than 2 Gy/hr.). Patients had to spend up to 1-3 days with applicators inserted to obtain the full therapeutic dose of 24 Gy

  19. Comparison of organ doses for patients undergoing balloon brachytherapy of the breast with HDR 192Ir or electronic sources using Monte Carlo simulations in a heterogeneous human phantom

    Purpose: Accelerated partial breast irradiation via interstitial balloon brachytherapy is a fast and effective treatment method for certain early stage breast cancers. The radiation can be delivered using a conventional high-dose rate (HDR) 192Ir gamma-emitting source or a novel electronic brachytherapy (eBx) source which uses lower energy x rays that do not penetrate as far within the patient. A previous study [A. Dickler, M. C. Kirk, N. Seif, K. Griem, K. Dowlatshahi, D. Francescatti, and R. A. Abrams, ''A dosimetric comparison of MammoSite high-dose-rate brachytherapy and Xoft Axxent electronic brachytherapy,'' Brachytherapy 6, 164-168 (2007)] showed that the target dose is similar for HDR 192Ir and eBx. This study compares these sources based on the dose received by healthy organs and tissues away from the treatment site. Methods: A virtual patient with left breast cancer was represented by a whole-body, tissue-heterogeneous female voxel phantom. Monte Carlo methods were used to calculate the dose to healthy organs in a virtual patient undergoing balloon brachytherapy of the left breast with HDR 192Ir or eBx sources. The dose-volume histograms for a few organs which received large doses were also calculated. Additional simulations were performed with all tissues in the phantom defined as water to study the effect of tissue inhomogeneities. Results: For both HDR 192Ir and eBx, the largest mean organ doses were received by the ribs, thymus gland, left lung, heart, and sternum which were close to the brachytherapy source in the left breast. eBx yielded mean healthy organ doses that were more than a factor of ∼1.4 smaller than for HDR 192Ir for all organs considered, except for the three closest ribs. Excluding these ribs, the average and median dose-reduction factors were ∼28 and ∼11, respectively. The volume distribution of doses in nearby soft tissue organs that were outside the PTV were also improved with eBx. However, the maximum dose to the closest rib

  20. A simplified analytical approach to estimate the parameters required for strength determination of HDR 192Ir brachytherapy sources using a Farmer-type ionization chamber

    Measuring the strength of high dose rate (HDR) 192Ir brachytherapy sources on receipt from the vendor is an important component of a quality assurance program. Owing to their ready availability in radiotherapy departments, the Farmer-type ionization chambers are also used to determine the strength of HDR 192Ir brachytherapy sources. The use of a Farmer-type ionization chamber requires the estimation of the scatter correction factor along with positioning error (c) and the constant of proportionality (f) to determine the strength of HDR 192Ir brachytherapy sources. A simplified approach based on a least squares method was developed for estimating the values of f and Ms. The seven distance method was followed to record the ionization chamber readings for parameterization of f and Ms. Analytically calculated values of Ms were used to determine the room scatter correction factor (Ksc). The Monte Carlo simulations were also carried out to calculate f and Ksc to verify the magnitude of the parameters determined by the proposed analytical approach. The value of f determined using the simplified analytical approach was found to be in excellent agreement with the Monte Carlo simulated value (within 0.7%). Analytically derived values of Ksc were also found to be in good agreement with the Monte Carlo calculated values (within 1.47%). Being far simpler than the presently available methods of evaluating f, the proposed analytical approach can be adopted for routine use by clinical medical physicists to estimate f by hand calculations. - Highlights: ► RAKR measurement of a brachytherapy source by 7 distance method requires the evaluation of ‘f’. ► A simplified analytical approach based on least square method to evaluate ‘f’ and ‘Ms’ was developed. ► Parameter ‘f’ calculated by proposed analytical approach was verified using the Monte Carlo method. ► Proposed analytical approach can be adopted for routine use to estimate ‘f’.

  1. Cost effective method of manual afterloading 192Ir brachytherapy

    Full text: In radiotherapy, brachytherapy mode of treatment has equal importance like the external beam radiotherapy. In our hospital we have manual afterloading 137Cs kit supplied by BRIT for intracavitary treatment of carcinoma cervix and vaginal cases. In July 1999, we also started afterloading 192Ir brachytherapy. For a hospital like ours, where funds are minimal, it is impossible to procure remote afterloading brachytherapy unit, which is very costly. So we have developed the cost-effective 192Ir manual brachytherapy and so far we have done 60 cases which include intraluminal and interstitial cases

  2. A practical implementation of the 2010 IPEM high dose rate brachytherapy code of practice for the calibration of {sup 192}Ir sources

    Awunor, O A; Lecomber, A R; Richmond, N; Walker, C, E-mail: Onuora.Awunor@stees.nhs.uk [Regional Medical Physics Department, James Cook University Hospital, Marton Road, Middlesbrough, TS4 3BW (United Kingdom)

    2011-08-21

    This paper details a practical method for deriving the reference air kerma rate calibration coefficient for Farmer NE2571 chambers using the UK Institute of Physics and Engineering in Medicine (IPEM) code of practice for the determination of the reference air kerma rate for HDR {sup 192}Ir brachytherapy sources based on the National Physical Laboratory (NPL) air kerma standard. The reference air kerma rate calibration coefficient was derived using pressure, temperature and source decay corrected ionization chamber response measurements over three successive {sup 192}Ir source clinical cycles. A secondary standard instrument (a Standard Imaging 1000 Plus well chamber) and four tertiary standard instruments (one additional Standard Imaging 1000 Plus well chamber and three Farmer NE2571 chambers housed in a perspex phantom) were used to provide traceability to the NPL primary standard and enable comparison of performance between the chambers. Conservative and optimized estimates on the expanded uncertainties (k = 2) associated with chamber response, ion recombination and reference air kerma rate calibration coefficient were determined. This was seen to be 2.3% and 0.4% respectively for chamber response, 0.2% and 0.08% respectively for ion recombination and 2.6% and 1.2% respectively for the calibration coefficient. No significant change in ion recombination with source decay was observed over the duration of clinical use of the respective {sup 192}Ir sources.

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

    Purpose: The absorbed dose to water is the fundamental reference quantity for brachytherapy treatment planning systems and thermoluminescence dosimeters (TLDs) have been recognized as the most validated detectors for measurement of such a dosimetric descriptor. The detector response in a wide energy spectrum as that of an192Ir brachytherapy source as well as the specific measurement medium which surrounds the TLD need to be accounted for when estimating the absorbed dose. This paper develops a methodology based on highly sensitive LiF:Mg,Cu,P TLDs to directly estimate the absorbed dose to water in liquid water around a high dose rate 192Ir brachytherapy source. Methods: Different experimental designs in liquid water and air were constructed to study the response of LiF:Mg,Cu,P TLDs when irradiated in several standard photon beams of the LNE-LNHB (French national metrology laboratory for ionizing radiation). Measurement strategies and Monte Carlo techniques were developed to calibrate the LiF:Mg,Cu,P detectors in the energy interval characteristic of that found when TLDs are immersed in water around an192Ir source. Finally, an experimental system was designed to irradiate TLDs at different angles between 1 and 11 cm away from an 192Ir source in liquid water. Monte Carlo simulations were performed to correct measured results to provide estimates of the absorbed dose to water in water around the 192Ir source. Results: The dose response dependence of LiF:Mg,Cu,P TLDs with the linear energy transfer of secondary electrons followed the same variations as those of published results. The calibration strategy which used TLDs in air exposed to a standard N-250 ISO x-ray beam and TLDs in water irradiated with a standard137Cs beam provided an estimated mean uncertainty of 2.8% (k = 1) in the TLD calibration coefficient for irradiations by the 192Ir source in water. The 3D TLD measurements performed in liquid water were obtained with a maximum uncertainty of 11% (k = 1) found

  4. Characterization of TLD-100 in powders for dosimetric quality control of 192 Ir sources used in brachytherapy of high dose rate

    The Secondary Standard Dosimetric at the National Institute of Nuclear Research (ININ) calibrated a lot of powdered TLD-100 (LiF:Mg,Ti) in terms of absorbed dose to water Dw for the energy of: 60Co, 137Cs, X rays of 250 and 50 kVp. Later on, it is carried out an interpolation of the calibration for the energy of the 192Ir. This calibration is part of a dosimetric quality control program, to solve the problems of traceability for the measurements carried out by the users of 192Ir sources employed in the treatments of High Dose Rate Brachytherapy (HDR) at the Mexican Republic. The calibrations of the radiation beams are made with the following protocols: IAEA TRS-398 for the 60Co for Dw, using a secondary standard ionization chamber PTW N30013 calibrated in Dw by the National Research Council (NRC, Canada). AAPM TG-43 for Dw in terms of the strength kerma Sk, calibrating this last one quantity for the 137Cs radioactive source, with a well chamber HDR 1000 PLUS traceable to the University of Wisconsin (US). AAPM TG-61 for X ray of 250 and 50 kVp for Dw start to Ka using field standard a Farmer chamber PTW 30001 traceable to K for the Central Laboratory of Electric Industries (CLEI, France). The calibration curves (CC) they built for the response of the powder TLD: RTLD vs Dw: For the energy of 60Co, 137Cs, X rays of 250 and 50 kVp. Fitting them with the least square method weighed by means of a polynomial of second grade that corrects the supra linearity of the response. iii. Each one of the curves was validated with a test by lack of fitting and for the Anderson Darling normality test, using the software MINITAB in both cases. iv. The sensibility factor (Fs) for each energy corresponds to the slope of the CC, v. The Fs for the two 192Ir sources used are interpolated: one for a Micro Selectron source and the other one a Vari Source source. Finally, a couple of capsules were sent to two hospitals that have the HDR Brachytherapy with sources of 192Ir and that

  5. Evaluation of Gafchromic EBT2 film for the measurement of anisotropy function for high-dose-rate 192Ir brachytherapy source with respect to thermoluminescent dosimetry

    Aim: The aim of this work was to assess the suitability of the use of a Gafchromic EBT2 film for the measurement of anisotropy function for micro Selectron HDR 192Ir (classic) source with a comparative dosimetry method using a Gafchromic EBT2 film and thermoluminescence dosimeters (TLDs). Background: Sealed linear radiation sources are commonly used for high dose rate (HDR) brachytherapy treatments. Due to self-absorption and oblique filtration of radiation in the source capsule material, an inherent anisotropy is present in the dose distribution around the source which can be described by a measurable two-dimensional anisotropy function, F(γ, Θ ). Materials and methods: Measurements were carried out in a specially designed and locally fabricated PMMA phantom with provisions to accommodate miniature LiF TLD rods and EBT2 film dosimeters at identical radial distances with respect to the 192Ir source. Results: The data of anisotropy function generated by the use of the Gafchromic EBT2 film method are in agreement with their TLD measured values within 4%. The produced data are also consistent with their experimental and Monte Carlo calculated results for this source available in the literature. Conclusion: Gafchromic EBT2 film was found to be a feasible dosimeter in determining anisotropy in the dose distribution of 192Ir source. It offers high resolution and is a viable alternative to TLD dosimetry at discrete points. The method described in this paper is useful for comparing the performances of detectors and can be applied for other brachytherapy sources as well. (authors)

  6. An absorbed dose to water standard for HDR 192Ir brachytherapy sources based on water calorimetry: Numerical and experimental proof-of-principle

    Water calorimetry is an established technique for absorbed dose to water measurements in external beams. In this paper, the feasibility of direct absorbed dose measurements for high dose rate (HDR) iridium-192 (192Ir) sources using water calorimetry is established. Feasibility is determined primarily by a balance between the need to obtain sufficient signal to perform a reproducible measurement, the effect of heat loss on the measured signal, and the positioning uncertainty affecting the source-detector distance. The heat conduction pattern generated in water by the Nucletron microSelectron-HDR 192Ir brachytherapy source was simulated using COMSOL MULTIPHYSICSTM software. Source heating due to radiation self-absorption was calculated using EGSnrcMP. A heat-loss correction kc was calculated as the ratio of the temperature rise under ideal conditions to temperature rise under realistic conditions. The calorimeter setup used a parallel-plate calorimeter vessel of 79 mm diameter and 1.12 mm thick front and rear glass windows located 24 mm apart. Absorbed dose was measured with two sources with nominal air kerma strengths of 38 000 and 21 000 U, at source-detector separations ranging from 24.7 to 27.6 mm and irradiation times of 36.0 to 80.0 s. The preliminary measured dose rate per unit air kerma strength of (0.502±0.007) μGy/(s U) compares well with the TG-43 derived 0.505 μGy/(s U). This work shows that combined dose uncertainties of significantly less than 5% can be achieved with only modest modifications of current water calorimetry techniques and instruments. This work forms the basis of a potential future absolute dose to water standard for HDR 192Ir brachytherapy

  7. An absorbed dose to water standard for HDR 192Ir brachytherapy sources based on water calorimetry: numerical and experimental proof-of-principle.

    Sarfehnia, Arman; Stewart, Kristin; Seuntjens, Jan

    2007-12-01

    Water calorimetry is an established technique for absorbed dose to water measurements in external beams. In this paper, the feasibility of direct absorbed dose measurements for high dose rate (HDR) iridium-192 (192Ir) sources using water calorimetry is established. Feasibility is determined primarily by a balance between the need to obtain sufficient signal to perform a reproducible measurement, the effect of heat loss on the measured signal, and the positioning uncertainty affecting the source-detector distance. The heat conduction pattern generated in water by the Nucletron microSelectron-HDR 192Ir brachytherapy source was simulated using COMSOL MULTIPHYSICS software. Source heating due to radiation self-absorption was calculated using EGSnrcMP. A heat-loss correction k(c) was calculated as the ratio of the temperature rise under ideal conditions to temperature rise under realistic conditions. The calorimeter setup used a parallel-plate calorimeter vessel of 79 mm diameter and 1.12 mm thick front and rear glass windows located 24 mm apart. Absorbed dose was measured with two sources with nominal air kerma strengths of 38 000 and 21 000 U, at source-detector separations ranging from 24.7 to 27.6 mm and irradiation times of 36.0 to 80.0 s. The preliminary measured dose rate per unit air kerma strength of (0.502 +/- 0.007) microGy/(s U) compares well with the TG-43 derived 0.505 microGy/(s U). This work shows that combined dose uncertainties of significantly less than 5% can be achieved with only modest modifications of current water calorimetry techniques and instruments. This work forms the basis of a potential future absolute dose to water standard for HDR 192Ir brachytherapy. PMID:18196821

  8. Sealed 192 Ir sources for industrial radiography

    This work presents the results obtained by the Post-Irradiation Examination Laboratory (LEPI) of INR Pitesti in production and selling of sealed 192 Ir sources for industrial radiography. The sealed 192 Ir sources are obtained by encapsulating iridium disks in stainless steel capsules by TIG welding. The iridium disks have the characteristics: - radionuclidic purity, at least 95% Ir; - density, at least 12 g/cm3; - height, 0.5 mm; - diameter, 3 mm. Tests for radioactive tightness of the capsules containing the 192 Ir sources are done by immersing the sealed source in water at 323 K temperature for 4 h and measuring the radioactivity of immersion water samples. The source is accepted as tightly enclosed if the water activity is less than 0.2 kBq (5 nCi). Six types of sealed 192 Ir sources are produced with maximum activity 4.4 TBq (120 Ci); 2.310 TBq (70 Ci); 1.155 TBq (35 Ci); 0.555 TBq (15 Ci); 0.185 TBq (5 Ci) and 0.037 TBq (1 Ci), with focal spots varying between 3 x 3 mm and 0.5 x 0.5 mm. The technological flux is described. In the period 1993-2000 LEPI has produced 350 sealed 192 Ir sources for industrial radiography with a total activity of 518 TBq (14,000 Ci) which were delivered to about 100 users of national industry

  9. SU-E-T-102: Determination of Dose Distributions and Water-Equivalence of MAGIC-F Polymer Gel for 60Co and 192Ir Brachytherapy Sources

    Quevedo, A; Nicolucci, P [University of Sao Paulo, Ribeirao Preto, SP (Brazil)

    2014-06-01

    Purpose: Analyse the water-equivalence of MAGIC-f polymer gel for {sup 60}Co and {sup 192}Ir clinical brachytherapy sources, through dose distributions simulated with PENELOPE Monte Carlo code. Methods: The real geometry of {sup 60} (BEBIG, modelo Co0.A86) and {sup 192}192Ir (Varian, model GammaMed Plus) clinical brachytherapy sources were modelled on PENELOPE Monte Carlo simulation code. The most probable emission lines of photons were used for both sources: 17 emission lines for {sup 192}Ir and 12 lines for {sup 60}. The dose distributions were obtained in a cubic water or gel homogeneous phantom (30 × 30 × 30 cm{sup 3}), with the source positioned in the middle of the phantom. In all cases the number of simulation showers remained constant at 10{sup 9} particles. A specific material for gel was constructed in PENELOPE using weight fraction components of MAGIC-f: wH = 0,1062, wC = 0,0751, wN = 0,0139, wO = 0,8021, wS = 2,58×10{sup −6} e wCu = 5,08 × 10{sup −6}. The voxel size in the dose distributions was 0.6 mm. Dose distribution maps on the longitudinal and radial direction through the centre of the source were used to analyse the water-equivalence of MAGIC-f. Results: For the {sup 60} source, the maximum diferences in relative doses obtained in the gel and water were 0,65% and 1,90%, for radial and longitudinal direction, respectively. For {sup 192}Ir, the maximum difereces in relative doses were 0,30% and 1,05%, for radial and longitudinal direction, respectively. The materials equivalence can also be verified through the effective atomic number and density of each material: Zef-MAGIC-f = 7,07 e .MAGIC-f = 1,060 g/cm{sup 3} and Zef-water = 7,22. Conclusion: The results showed that MAGIC-f is water equivalent, consequently being suitable to simulate soft tissue, for Cobalt and Iridium energies. Hence, gel can be used as a dosimeter in clinical applications. Further investigation to its use in a clinical protocol is needed.

  10. Cluster pattern analysis of energy deposition sites for the brachytherapy sources 103Pd, 125I, 192Ir, 137Cs, and 60Co

    Analysing the pattern of energy depositions may help elucidate differences in the severity of radiation-induced DNA strand breakage for different radiation qualities. It is often claimed that energy deposition (ED) sites from photon radiation form a uniform random pattern, but there is indication of differences in RBE values among different photon sources used in brachytherapy. The aim of this work is to analyse the spatial patterns of EDs from 103Pd, 125I, 192Ir, 137Cs sources commonly used in brachytherapy and a 60Co source as a reference radiation. The results suggest that there is both a non-uniform and a uniform random component to the frequency distribution of distances to the nearest neighbour ED. The closest neighbouring EDs show high spatial correlation for all investigated radiation qualities, whilst the uniform random component dominates for neighbours with longer distances for the three higher mean photon energy sources (192Ir, 137Cs, and 60Co). The two lower energy photon emitters (103Pd and 125I) present a very small uniform random component. The ratio of frequencies of clusters with respect to 60Co differs up to 15% for the lower energy sources and less than 2% for the higher energy sources when the maximum distance between each pair of EDs is 2 nm. At distances relevant to DNA damage, cluster patterns can be differentiated between the lower and higher energy sources. This may be part of the explanation to the reported difference in RBE values with initial DSB yields as an endpoint for these brachytherapy sources. (paper)

  11. Dosimetric impact of an 192Ir brachytherapy source cable length modeled using a grid-based Boltzmann transport equation solver

    Purpose: To evaluate the dose distributions of an 192Ir source (model VS2000) in homogeneous water geometry calculated using a deterministic grid-based Boltzmann transport equation solver (GBBS) in the commercial treatment planning system (TPS) (BRACHYVISION-ACUROS v8.8). Methods: Using percent dose differences (%ΔD), the GBBS (BV-ACUROS) was compared to the (1) published TG-43 data, (2) MCNPX Monte Carlo (MC) simulations of the 192Ir source centered in a 15 cm radius water sphere, and (3) TG-43 output from the TPS using vendor supplied (BV-TG43-vendor) and user extended (BV-TG43-extended) 2D anisotropy functions F(r,θ). BV-ACUROS assumes 1 mm of NiTi cable, while the TPS TG-43 algorithm uses data based on a 15 cm cable. MC models of various cable lengths were simulated. Results: The MC simulations resulted in >20% dose deviations along the cable for 1, 2, and 3 mm cable lengths relative to 15 cm. BV-ACUROS comparisons with BV-TG43-vendor and BV-TG43-extended yielded magnitude of differences, consistent with those seen in MC simulations. However, differences >20% extended further (θ≤10 deg.) when using the vendor supplied anisotropy function Fven(r,θ). These differences were also seen in comparisons of F(r,θ) derived from the TPS output. Conclusions: The results suggest that %ΔD near the cable region is larger than previously estimated. The spatial distribution of the dose deviation is highly dependent on the reference TG-43 data used to compare to GBBS. The differences observed, while important to realize, should not have an impact on clinical dosimetry in homogeneous water.

  12. A generic high-dose rate {sup 192}Ir brachytherapy source for evaluation of model-based dose calculations beyond the TG-43 formalism

    Ballester, Facundo, E-mail: Facundo.Ballester@uv.es [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Carlsson Tedgren, Åsa [Department of Medical and Health Sciences (IMH), Radiation Physics, Faculty of Health Sciences, Linköping University, Linköping SE-581 85, Sweden and Department of Medical Physics, Karolinska University Hospital, Stockholm SE-171 76 (Sweden); Granero, Domingo [Department of Radiation Physics, ERESA, Hospital General Universitario, Valencia E-46014 (Spain); Haworth, Annette [Department of Physical Sciences, Peter MacCallum Cancer Centre and Royal Melbourne Institute of Technology, Melbourne, Victoria 3000 (Australia); Mourtada, Firas [Department of Radiation Oncology, Helen F. Graham Cancer Center, Christiana Care Health System, Newark, Delaware 19713 (United States); Fonseca, Gabriel Paiva [Instituto de Pesquisas Energéticas e Nucleares – IPEN-CNEN/SP, São Paulo 05508-000, Brazil and Department of Radiation Oncology (MAASTRO), GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Zourari, Kyveli; Papagiannis, Panagiotis [Medical Physics Laboratory, Medical School, University of Athens, 75 MikrasAsias, Athens 115 27 (Greece); Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Siebert, Frank-André [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel 24105 (Germany); Sloboda, Ron S. [Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada); and others

    2015-06-15

    Purpose: In order to facilitate a smooth transition for brachytherapy dose calculations from the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) formalism to model-based dose calculation algorithms (MBDCAs), treatment planning systems (TPSs) using a MBDCA require a set of well-defined test case plans characterized by Monte Carlo (MC) methods. This also permits direct dose comparison to TG-43 reference data. Such test case plans should be made available for use in the software commissioning process performed by clinical end users. To this end, a hypothetical, generic high-dose rate (HDR) {sup 192}Ir source and a virtual water phantom were designed, which can be imported into a TPS. Methods: A hypothetical, generic HDR {sup 192}Ir source was designed based on commercially available sources as well as a virtual, cubic water phantom that can be imported into any TPS in DICOM format. The dose distribution of the generic {sup 192}Ir source when placed at the center of the cubic phantom, and away from the center under altered scatter conditions, was evaluated using two commercial MBDCAs [Oncentra{sup ®} Brachy with advanced collapsed-cone engine (ACE) and BrachyVision ACUROS{sup TM}]. Dose comparisons were performed using state-of-the-art MC codes for radiation transport, including ALGEBRA, BrachyDose, GEANT4, MCNP5, MCNP6, and PENELOPE2008. The methodologies adhered to recommendations in the AAPM TG-229 report on high-energy brachytherapy source dosimetry. TG-43 dosimetry parameters, an along-away dose-rate table, and primary and scatter separated (PSS) data were obtained. The virtual water phantom of (201){sup 3} voxels (1 mm sides) was used to evaluate the calculated dose distributions. Two test case plans involving a single position of the generic HDR {sup 192}Ir source in this phantom were prepared: (i) source centered in the phantom and (ii) source displaced 7 cm laterally from the center. Datasets were independently produced by

  13. Primary standardization of the HDR 192Ir source in terms of air kerma strength

    Establishing a primary standard of AKS at the Standards Laboratory and offering traceable calibration to all the hospitals that make use of HDR 192Ir, in brachytherapy is important. With this objective, the primary standardization of the HDR 192Ir source was undertaken. Details of the work are presented

  14. Water equivalent phantom materials for 192Ir brachytherapy

    Schoenfeld, Andreas A.; Harder, Dietrich; Poppe, Björn; Chofor, Ndimofor

    2015-12-01

    Several solid phantom materials have been tested regarding their suitability as water substitutes for dosimetric measurements in brachytherapy with 192Ir as a typical high energy photon emitter. The radial variations of the spectral photon fluence, of the total, primary and scattered photon fluence and of the absorbed dose to water in the transversal plane of the tested cylindrical phantoms surrounding a centric and coaxially arranged Varian GammaMed afterloading 192Ir brachytherapy source were Monte-Carlo simulated in EGSnrc. The degree of water equivalence of a phantom material was evaluated by comparing the radial dose-to-water profile in the phantom material with that in water. The phantom size was varied over a large range since it influences the dose contribution by scattered photons with energies diminished by single and multiple Compton scattering. Phantom axis distances up to 10 cm were considered as clinically relevant. Scattered photons with energies reaching down into the 25 keV region dominate the photon fluence at source distances exceeding 3.5 cm. The tested phantom materials showed significant differences in the degree of water equivalence. In phantoms with radii up to 10 cm, RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, and Plastic Water LR phantoms show excellent water equivalence with dose deviations from a water phantom not exceeding 0.8%, while Original Plastic Water (as of 2015), Plastic Water (1995), Blue Water, polyethylene, and polystyrene show deviations up to 2.6%. For larger phantom radii up to 30 cm, the deviations for RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, and Plastic Water LR remain below 1.4%, while Original Plastic Water (as of 2015), Plastic Water (1995), Blue Water, polyethylene, and polystyrene produce deviations up to 8.1%. PMMA plays a separate role, with deviations up to 4.3% for radii not exceeding 10 cm, but below 1% for radii up to 30 cm. As suggested by

  15. Water equivalent phantom materials for (192)Ir brachytherapy.

    Schoenfeld, Andreas A; Harder, Dietrich; Poppe, Björn; Chofor, Ndimofor

    2015-12-21

    Several solid phantom materials have been tested regarding their suitability as water substitutes for dosimetric measurements in brachytherapy with (192)Ir as a typical high energy photon emitter. The radial variations of the spectral photon fluence, of the total, primary and scattered photon fluence and of the absorbed dose to water in the transversal plane of the tested cylindrical phantoms surrounding a centric and coaxially arranged Varian GammaMed afterloading (192)Ir brachytherapy source were Monte-Carlo simulated in EGSnrc. The degree of water equivalence of a phantom material was evaluated by comparing the radial dose-to-water profile in the phantom material with that in water. The phantom size was varied over a large range since it influences the dose contribution by scattered photons with energies diminished by single and multiple Compton scattering. Phantom axis distances up to 10 cm were considered as clinically relevant. Scattered photons with energies reaching down into the 25 keV region dominate the photon fluence at source distances exceeding 3.5 cm.The tested phantom materials showed significant differences in the degree of water equivalence. In phantoms with radii up to 10 cm, RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, and Plastic Water LR phantoms show excellent water equivalence with dose deviations from a water phantom not exceeding 0.8%, while Original Plastic Water (as of 2015), Plastic Water (1995), Blue Water, polyethylene, and polystyrene show deviations up to 2.6%. For larger phantom radii up to 30 cm, the deviations for RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, and Plastic Water LR remain below 1.4%, while Original Plastic Water (as of 2015), Plastic Water (1995), Blue Water, polyethylene, and polystyrene produce deviations up to 8.1%. PMMA plays a separate role, with deviations up to 4.3% for radii not exceeding 10 cm, but below 1% for radii up to 30 cm.As suggested

  16. Tumor dose enhancement by nanoparticles during high dose rate 192 Ir brachytherapy

    Mansour Zabihzadeh

    2015-01-01

    Conclusion: Injecting of high-Z gold NPs into tumor increases the absorbed dose of tumor irradiated with 192 Ir HDR brachytherapy source. Size, geometry, concentration, and distribution model of NPs and tumor depth are crucial factors to accurately estimate the DEF.

  17. Dosimetric accuracy of a deterministic radiation transport based 192Ir brachytherapy treatment planning system. Part I: Single sources and bounded homogeneous geometries

    Purpose: The aim of this work is to validate a deterministic radiation transport based treatment planning system (TPS) for single 192Ir brachytherapy source dosimetry in homogeneous water geometries. Methods: TPS results were obtained using the deterministic radiation transport option of a BRACHYVISION v. 8.8 system for three characteristic source designs (VS2000, GMPlus HDR, and GMPlus PDR) with each source either centered in a 15 cm radius spherical water phantom, or positioned at varying distance away from the phantom center. Corresponding MC simulations were performed using the MCNPX code v.2.5.0 and source geometry models prepared using information provided by the manufacturers. Results: Comparison in terms of the AAPM TG-43 dosimetric formalism quantities, as well as dose rate distributions per unit air kerma strength with a spatial resolution of 0.1 cm, yielded close agreement between TPS and MC results for the sources centered in the phantom. Besides some regions close to the source longitudinal axes where discrepancies could be characterized as systematic, overall agreement for all three sources studied is comparable to the statistical (type A) uncertainty of MC simulations (1% at the majority of points in the geometry increasing to 2%-3% at points lying both away from the source center and close to the source longitudinal axis). A corresponding good agreement was also found between TPS and MC results for the sources positioned away from the phantom center. Conclusions: Results of this work attest the capability of the TPS to accurately account for the scatter conditions regardless of the size or shape of a given geometry of dosimetric interest, and the position of a source within it. This is important since, as shown in the literature and summarized also in this work, these factors could introduce a significant dosimetric effect that is currently ignored in clinical treatment planning. It is concluded that the implementation of the deterministic radiation

  18. Verification of the dose from an Iridium-192 (192Ir) sealed source absorbed by an implantable cardioverter defibrillator (ICD) during uterine intracavitary brachytherapy

    The purpose of this study was to verify the dose absorbed by an implantable cardioverter defibrillator (ICD) from an 192Ir sealed source during uterine intracavitary brachytherapy, and to confirm its immunity to radiation effects. First, prior to treatment, the doses around the ICD position of an anthromorphic phantom were evaluated. Next, we also measured the dose at the ICD position using a fluorescent glass dosimeter and silicon diode dosimeter during the treatment of intracavitary brachytherapy of a patient implanted with an ICD. The results of the phantom study showed the dose percentage at the ICD location, 2 cm deep, to be 0.074% of the prescribed dose. The results of a treatment study similarly showed the dose, measured using a fluorescent glass dosimeter in the ICD position, to be 0.071% of the prescribed dose. During the application of the total prescribed dose, 30 Gy/5 fraction, the dose at the surface of the ICD position was estimated to be 21.2 mGy, well below the 1 Gy maximum recommended in the JASTRO guidelines. We regard dose verification and monitoring during treatment to be both necessary and useful in the treatment of individual cases. (author)

  19. The non-uniformity correction factor for the cylindrical ionization chambers in dosimetry of an HDR 192Ir brachytherapy source

    Majumdar Bishnu

    2006-01-01

    Full Text Available The aim of this study is to derive the non-uniformity correction factor for the two therapy ionization chambers for the dose measurement near the brachytherapy source. The two ionization chambers of 0.6 cc and 0.1 cc volume were used. The measurement in air was performed for distances between 0.8 cm and 20 cm from the source in specially designed measurement jig. The non-uniformity correction factors were derived from the measured values. The experimentally derived factors were compared with the theoretically calculated non-uniformity correction factors and a close agreement was found between these two studies. The experimentally derived non-uniformity correction factor supports the anisotropic theory.

  20. Qualification tests for 192Ir sealed sources

    This paper describes the results of qualification tests for 192Ir sealed sources, available in Testing and Nuclear Expertise Laboratory of National Institute for Physics and Nuclear Engineering 'Horia Hulubei' (I.F.I.N.-HH), Romania. These sources had to be produced in I.F.I.N.-HH and were tested in order to obtain the authorization from The National Commission for Nuclear Activities Control (CNCAN). The sources are used for gammagraphy procedures or in gammadefectoscopy equipments. Tests, measurement methods and equipments used, comply with CNCAN, AIEA and International Quality Standards and regulations. The qualification tests are: 1. Radiological tests and measurements: dose equivalent rate at 1 m; tightness; dose equivalent rate at the surface of the transport and storage container; external unfixed contamination of the container surface. 2. Mechanical and climatic tests: thermal shock; external pressure; mechanic shock; vibrations; boring; thermal conditions for storage and transportation. Passing all tests, it was obtained the Radiological Security Authorization for producing the 192Ir sealed sources. Now IFIN-HH can meet many demands for this sealed sources, as the only manufacturer in Romania

  1. High beta and electron dose from 192Ir: implications for 'gamma' intravascular brachytherapy

    Purpose: Trains of multiple 192Ir seeds are used in many clinical trials for intravascular brachytherapy. 192Ir source is commonly considered as a gamma emitter, despite the understanding that this radionuclide also emits a wide range of electron and beta energies, with a similar range of energy. The high dose from betas and electrons in the submillimeter range due to unsealed ends of seed sources should be precisely quantified to fully understand the backdrop for complications associated with 192Ir coronary artery brachytherapy. Methods and Materials: Monte Carlo simulations (MCNP4C code) were performed for a model 5-seed 192Ir train used in SCRIPPS, GAMMA, and the Washington Radiation for In-Stent Restenosis (WRIST) randomized clinical trials. A stack of radiochromic films was also used to measure the dose distributions for an actual 6-seed train. Results: In the submillimeter range very close to the source, Monte Carlo results show that betas and electrons deposit a higher dose than 192Ir photons (gamma and X-rays) over the interseed gap. A high luminal dose from the combined effects of betas, electrons, and photons emitted from 192Ir can be deposited, particularly between seeds. When prescribing 15 Gy at 2 mm, the combined dose can be as high as 160 Gy at 0.5 mm. Different peak doses near the interseed gaps were noted, which may be due to variability of seed-end surfaces and nonuniformity of seed activity within a real multiseed train. Dose-volume histograms (DVH) of lumen surfaces were evaluated for an eccentric seed train. The DVH parameters indicating the extent of hot spots in the lumen wall, DV10, DV5, DV2, and DV1 (dose received by 10, 5, 2, 1% respectively of the total lumen surface), can be as high as 55, 76, 81, and 155 Gy for a lumen with 3-mm diameter, and 75, 80, 110, and 158 Gy for a narrow 2-mm lumen. Conclusion: 192Ir multiple seed trains used in the SCRIPPS, GAMMA, and WRIST trials can deposit a very high dose to the luminal wall. A particularly

  2. Optimization of deterministic transport parameters for the calculation of the dose distribution around a high dose-rate 192Ir brachytherapy source

    The goal of this work was to calculate the dose distribution around a high dose-rate 192Ir brachytherapy source using a multi-group discrete ordinates code and then to compare the results with a Monte Carlo calculated dose distribution. The unstructured tetrahedral mesh discrete ordinates code Attila version 6.1.1 was used to calculate the photon kerma rate distribution in water around the Nucletron microSelectron mHDRv2 source. MCNPX 2.5.c was used to compute the Monte Carlo water photon kerma rate distribution. Two hundred million histories were simulated, resulting in standard errors of the mean of less than 3% overall. The number of energy groups, Sn (angular order), Pn (scattering order), and mesh elements were varied in addition to the method of analytic ray tracing to assess their effects on the deterministic solution. Water photon kerma rate matrices were exported from both codes into an in-house data analysis software. This software quantified the percent dose difference distribution, the number of points within ±3% and ±5%, and the mean percent difference between the two codes. The data demonstrated that a 5 energy-group cross-section set calculated results to within 0.5% of a 15 group cross-section set. S12 was sufficient to resolve the solution in angle. P2 expansion of the scattering cross-section was necessary to compute accurate distributions. A computational mesh with 55 064 tetrahedral elements in a 30 cm diameter phantom resolved the solution spatially. An efficiency factor of 110 with the above parameters was realized in comparison to MC methods. The Attila code provided an accurate and efficient solution of the Boltzmann transport equation for the mHDRv2 source

  3. Development on Monte Carlo methodology with scatter correction factor of afterloading 192 Ir source

    Objective: To facilitate activity measurement by using the thimble ionization chamber in hospitals, to obtain air kerma scatter correction factor of medical afterloading of 192Ir source by developing an available and convenient calculation method. Methods: According to International Atomic Energy Agency (IAEA) 1079 Report to calculate the scatter correction factor of 192Ir source, to measure air kerma of 192Ir source with and without lead shield using thimble ionization chamber. Simulation measurement conditions were used to calculate scatter correction factor of 192Ir source and comparison was made between experimental results and literature records. At the same time, the different ionization chamber models were simulated at different room sizes to obtain scattering correction factor of 192 Ir source. Results: Comparison was made between the simulation scatter correction factors of 192Ir source and experiment by the shadow shield, and the relative deviation was 0.8%. The deviation of the 192Ir activity calculated according to the simulated scatter correction factor and measured by well type ionization chamber was 2.4%. By comparison between the calculated results by using two kinds of spherical ionization chamber and those ones deduced by IAEA 1079 Report,the relative deviations ranged within 0.3%-0.4%. Five different types of thimble ionization chamber and different room sizes were simulated and calculated by MC simulation, with the relative deviation within 3%. Conclusions: Monte Carlo simulation method for calculating afterloading 192Ir source's scatter correction factor is feasible, and this method is convenient for use in the thimble chamber for brachytherapy QA work in the hospital. (authors)

  4. Calibration of well-type chambers in Brazil using 192Ir HDR sources

    The results obtained by performing of a traceable calibration service for well-type reentrant ionization chamber for HDR 192Ir sources used in brachytherapy physical procedures at the Laboratorio de Ciencias Radiologicas from Universidade do Estado do Rio de Janeiro -LCR/UERJ are described. (author)

  5. Determination of absorbed dose in water at the reference point D(r{sub 0},{theta}{sub 0}) for an {sup 192}Ir HDR brachytherapy source using a Fricke system

    Austerlitz, C.; Mota, H. C.; Sempau, J.; Benhabib, S. M.; Campos, D.; Allison, R.; Almeida, C. E. de; Zhu, D.; Sibata, C. H. [Department of Radiation Oncology, East Carolina University, Greenville, North Carolina 27834 (United States); Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, 08028 Barcelona (Spain); Department of Radiation Oncology, East Carolina University, Greenville, North Carolina 27834 (United States); Laboratorio de Cie circumflex ncias Radiologicas, Universidade do Estado do Rio de Janeiro, 20550 Rio de Janeiro (Brazil); Department of Radiation Oncology, East Carolina University, Greenville, North Carolina 27834 (United States)

    2008-12-15

    A ring-shaped Fricke device was developed to measure the absolute dose on the transverse bisector of a {sup 192}Ir high dose rate (HDR) source at 1 cm from its center in water, D(r{sub 0},{theta}{sub 0}). It consists of a polymethylmethacrylate (PMMA) rod (axial axis) with a cylindrical cavity at its center to insert the {sup 192}Ir radioactive source. A ring cavity around the source with 1.5 mm thickness and 5 mm height is centered at 1 cm from the central axis of the source. This ring cavity is etched in a disk shaped base with 2.65 cm diameter and 0.90 cm thickness. The cavity has a wall around it 0.25 cm thick. This ring is filled with Fricke solution, sealed, and the whole assembly is immersed in water during irradiations. The device takes advantage of the cylindrical geometry to measure D(r{sub 0},{theta}{sub 0}). Irradiations were performed with a Nucletron microselectron HDR unit loaded with an {sup 192}Ir Alpha Omega radioactive source. A Spectronic 1001 spectrophotometer was used to measure the optical absorbance using a 1 mL quartz cuvette with 1.00 cm light pathlength. The PENELOPE Monte Carlo code (MC) was utilized to simulate the Fricke device and the {sup 192}Ir Alpha Omega source in detail to calculate the perturbation introduced by the PMMA material. A NIST traceable calibrated well type ionization chamber was used to determine the air-kerma strength, and a published dose-rate constant was used to determine the dose rate at the reference point. The time to deliver 30.00 Gy to the reference point was calculated. This absorbed dose was then compared to the absorbed dose measured by the Fricke solution. Based on MC simulation, the PMMA of the Fricke device increases the D(r{sub 0},{theta}{sub 0}) by 2.0%. Applying the corresponding correction factor, the D(r{sub 0},{theta}{sub 0}) value assessed with the Fricke device agrees within 2.0% with the expected value with a total combined uncertainty of 3.43%(k=1). The Fricke device provides a promising

  6. Real-size CT slices to optimize brachytherapy treatments in vaginal moulds using 192-IR

    INTRODUCTION. We use individualized vaginal moulds with 192-Ir as radioactive source. This technique of treatment allows us to perform a previous dosimetric study and the knowledge of the sources spatial distribution. Their elaboration is slow but it offers an individualized treatment of each patient. To optimize the treatment we perform a CT the day after of the application. METHODS. The patients are referred to the Radiology Dp. with hyperdense dummy sources in the plastic tubes of the vaginal mould. After the selection of the central perpendicular plane to the dummy sources, some real size CT slices (RSCTS) are obtained every 5 mm (2mm. of thickness). Then, the dosimetric study is performed. RESULTS. RSCTS give us information about the localization of the sources and a more precise knowledge of the dose received by the bladder, rectum, vaginal vault and the tumor in each plane of interest. However, in some cases the fat plane between the vaginal vault and the rectum and bladder doesn't exist; this is a limitation in the identification of both structures. Likewise, in the cases that the rectum is collapsed when the CT is performed we lost this information too. CONCLUSIONS. 1- Probably this technique will allow us to correlate the dose received by the different structures and the late toxicity. 2- RSCTS allow us a good optimization of the brachytherapy in the plastic tube technique in centers without sophisticated planning systems. 3- RSCTS is a good system of quality control in the vaginal moulds with 192-IR

  7. Dosimetric accuracy of a deterministic radiation transport based 192Ir brachytherapy treatment planning system. Part II: Monte Carlo and experimental verification of a multiple source dwell position plan employing a shielded applicator

    Purpose: The aim of this work is the dosimetric validation of a deterministic radiation transport based treatment planning system (BRACHYVISION v. 8.8, referred to as TPS in the following) for multiple 192Ir source dwell position brachytherapy applications employing a shielded applicator in homogeneous water geometries. Methods: TPS calculations for an irradiation plan employing seven VS2000 192Ir high dose rate (HDR) source dwell positions and a partially shielded applicator (GM11004380) were compared to corresponding Monte Carlo (MC) simulation results, as well as experimental results obtained using the VIP polymer gel-magnetic resonance imaging three-dimensional dosimetry method with a custom made phantom. Results: TPS and MC dose distributions were found in agreement which is mainly within ±2%. Considerable differences between TPS and MC results (greater than 2%) were observed at points in the penumbra of the shields (i.e., close to the edges of the ''shielded'' segment of the geometries). These differences were experimentally verified and therefore attributed to the TPS. Apart from these regions, experimental and TPS dose distributions were found in agreement within 2 mm distance to agreement and 5% dose difference criteria. As shown in this work, these results mark a significant improvement relative to dosimetry algorithms that disregard the presence of the shielded applicator since the use of the latter leads to dosimetry errors on the order of 20%-30% at the edge of the ''unshielded'' segment of the geometry and even 2%-6% at points corresponding to the potential location of the target volume in clinical applications using the applicator (points in the unshielded segment at short distances from the applicator). Conclusions: Results of this work attest the capability of the TPS to accurately account for the scatter conditions and the increased attenuation involved in HDR brachytherapy applications employing multiple source dwell positions and partially

  8. Dosimetric accuracy of a deterministic radiation transport based {sup 192}Ir brachytherapy treatment planning system. Part II: Monte Carlo and experimental verification of a multiple source dwell position plan employing a shielded applicator

    Petrokokkinos, L.; Zourari, K.; Pantelis, E.; Moutsatsos, A.; Karaiskos, P.; Sakelliou, L.; Seimenis, I.; Georgiou, E.; Papagiannis, P. [Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Department of Physics, Nuclear and Particle Physics Section, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Medical Physics Laboratory, Medical School, Democritus University of Thrace, 2nd Building of Preclinical Section, University Campus, Alexandroupolis 68100 (Greece); Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece)

    2011-04-15

    Purpose: The aim of this work is the dosimetric validation of a deterministic radiation transport based treatment planning system (BRACHYVISION v. 8.8, referred to as TPS in the following) for multiple {sup 192}Ir source dwell position brachytherapy applications employing a shielded applicator in homogeneous water geometries. Methods: TPS calculations for an irradiation plan employing seven VS2000 {sup 192}Ir high dose rate (HDR) source dwell positions and a partially shielded applicator (GM11004380) were compared to corresponding Monte Carlo (MC) simulation results, as well as experimental results obtained using the VIP polymer gel-magnetic resonance imaging three-dimensional dosimetry method with a custom made phantom. Results: TPS and MC dose distributions were found in agreement which is mainly within {+-}2%. Considerable differences between TPS and MC results (greater than 2%) were observed at points in the penumbra of the shields (i.e., close to the edges of the ''shielded'' segment of the geometries). These differences were experimentally verified and therefore attributed to the TPS. Apart from these regions, experimental and TPS dose distributions were found in agreement within 2 mm distance to agreement and 5% dose difference criteria. As shown in this work, these results mark a significant improvement relative to dosimetry algorithms that disregard the presence of the shielded applicator since the use of the latter leads to dosimetry errors on the order of 20%-30% at the edge of the ''unshielded'' segment of the geometry and even 2%-6% at points corresponding to the potential location of the target volume in clinical applications using the applicator (points in the unshielded segment at short distances from the applicator). Conclusions: Results of this work attest the capability of the TPS to accurately account for the scatter conditions and the increased attenuation involved in HDR brachytherapy applications

  9. Radiation levels in Cath Lab and occupational exposures during manual 192Ir intracoronary brachytherapy

    Intracoronary brachytherapy is a new modality of radiation therapy and is being used to reduce the rate of restenosis after angioplasty. Clinical trials for evaluation of safety and efficacy of manually implanted 192Ir seed ribbons are underway at various cardiology centres in India. 192Ir emits high energy gamma rays (0.136 -1.06 MeV), which causes concern regarding safety of the personnel when these sources are manually used in the cardiac catheterization laboratory (Cath Lab) for intracoronary irradiation. Radiation levels in Cath Lab and exposures to personnel have been measured at 6 different cardiology centres in the country during 8 different clinical trials using radiation survey meter, personnel monitoring badges and pocket dosimeters. Activities of 192Ir seed ribbons used in these clinical trials were in the range of 5.55 - 14.8 GBq. Measured radiation levels behind the mobile lead shields, at the top of lead shields, near the patient head, near the patient toes and at the main door of the Cath Lab were in the range of 2.6-20, 50-256, 385-450, 22-225 and 2-16 μSv/hr/3.7GBq, respectively. Measured effective doses to occupational workers were in range of 14-100 μSv/procedure/3.7GBq. Based on these measurements, user institutions have been advised to use lead glass mounted L-shaped mobile lead shields with proper orientation during clinical trials, avoid unwanted occupancy in the Cath Lab and around the patient during irradiation and use conveniently long forceps or tongs for implantation and removal of sources. (author)

  10. Dosimetric characterization of round HDR {sup 192}Ir AccuBoost applicators for breast brachytherapy

    Rivard, Mark J.; Melhus, Christopher S.; Wazer, David E.; Bricault, Raymond J. Jr. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Advanced Radiation Therapy, Billerica, Massachusetts 01821 (United States)

    2009-11-15

    Purpose: The AccuBoost brachytherapy system applies HDR {sup 192}Ir beams peripherally to the breast using collimating applicators. The purpose of this study was to benchmark Monte Carlo simulations of the HDR {sup 192}Ir source, to dosimetrically characterize the round applicators using established Monte Carlo simulation and radiation measurement techniques and to gather data for clinical use. Methods: Dosimetric measurements were performed in a polystyrene phantom, while simulations estimated dose in air, liquid water, polystyrene and ICRU 44 breast tissue. Dose distribution characterization of the 4-8 cm diameter collimators was performed using radiochromic EBT film and air ionization chambers. Results: The central axis dose falloff was steeper for the 4 cm diameter applicator in comparison to the 8 cm diameter applicator, with surface to 3 cm depth-dose ratios of 3.65 and 2.44, respectively. These ratios did not considerably change when varying the phantom composition from breast tissue to polystyrene, phantom thickness from 4 to 8 cm, or phantom radius from 8 to 15 cm. Dose distributions on the central axis were fitted to sixth-order polynomials for clinical use in a hand calculation spreadsheet (i.e., nomogram). Dose uniformity within the useful applicator apertures decreased as depth-dose increased. Conclusions: Monte Carlo benchmarking simulations of the HDR {sup 192}Ir source using the MCNP5 radiation transport code indicated agreement within 1% of the published results over the radial/angular region of interest. Changes in phantom size and radius did not cause noteworthy changes in the central axis depth-dose. Polynomial fit depth-dose curves provide a simple and accurate basis for a nomogram.

  11. Dosimetric characterization of round HDR 192Ir AccuBoost applicators for breast brachytherapy

    Purpose: The AccuBoost brachytherapy system applies HDR 192Ir beams peripherally to the breast using collimating applicators. The purpose of this study was to benchmark Monte Carlo simulations of the HDR 192Ir source, to dosimetrically characterize the round applicators using established Monte Carlo simulation and radiation measurement techniques and to gather data for clinical use. Methods: Dosimetric measurements were performed in a polystyrene phantom, while simulations estimated dose in air, liquid water, polystyrene and ICRU 44 breast tissue. Dose distribution characterization of the 4-8 cm diameter collimators was performed using radiochromic EBT film and air ionization chambers. Results: The central axis dose falloff was steeper for the 4 cm diameter applicator in comparison to the 8 cm diameter applicator, with surface to 3 cm depth-dose ratios of 3.65 and 2.44, respectively. These ratios did not considerably change when varying the phantom composition from breast tissue to polystyrene, phantom thickness from 4 to 8 cm, or phantom radius from 8 to 15 cm. Dose distributions on the central axis were fitted to sixth-order polynomials for clinical use in a hand calculation spreadsheet (i.e., nomogram). Dose uniformity within the useful applicator apertures decreased as depth-dose increased. Conclusions: Monte Carlo benchmarking simulations of the HDR 192Ir source using the MCNP5 radiation transport code indicated agreement within 1% of the published results over the radial/angular region of interest. Changes in phantom size and radius did not cause noteworthy changes in the central axis depth-dose. Polynomial fit depth-dose curves provide a simple and accurate basis for a nomogram.

  12. Determination of the Fricke G value for HDR 192Ir sources using ionometric measurements

    High Dose Rate (HDR) brachytherapy using 192Ir is widely accepted as an important treatment option, and it thus requires an accurate dosimetry standard. However, a dosimetry standard for the direct measurement of absolute dose to water is currently not available. The dose to water conversion is calculated via the dose rate constant Λ and several correction factors accounting for the scatter, attenuation, and anisotropy of the dose distribution, among other effects. Two potentially useful procedures have been reported, including one by Sarfehnia et al. [3,4], which used a water-based calorimeter with an uncertainty of 1.9% for k=1, and a second by Austerlitz et al. and de Almeida et al., which used Fricke dosimetry with estimated uncertainties of 3.9% for k=1 and 1.4% for k=1, respectively. Chemical dosimetry using a standard FeSO4 solution has shown potential to be a reliable standard of absorbed dose for the HDR 192Ir source. A major uncertainty is associated with the G values reported by Fregene, which had a numerical value of 1.1 %. However, that reference provided very little detail of the experimental procedures for the 192Ir source. The G value may be obtained by using a calorimeter or ionometric measurements. In the absence of calorimetric data, this paper makes an attempt to measure the G value for the HDR 192Ir sources using ionometric measurements and recommendations from dosimetry protocols. (author)

  13. Determination of the Fricke G value for HDR {sup 192}Ir sources using ionometric measurements

    Franco, L.; Coelho, M.; Almeida, C.E. de [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Lab. de Ciencias Radiologicas; Gavazza, S. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    High Dose Rate (HDR) brachytherapy using {sup 192}Ir is widely accepted as an important treatment option, and it thus requires an accurate dosimetry standard. However, a dosimetry standard for the direct measurement of absolute dose to water is currently not available. The dose to water conversion is calculated via the dose rate constant {Lambda} and several correction factors accounting for the scatter, attenuation, and anisotropy of the dose distribution, among other effects. Two potentially useful procedures have been reported, including one by Sarfehnia et al. [3,4], which used a water-based calorimeter with an uncertainty of 1.9% for k=1, and a second by Austerlitz et al. and de Almeida et al., which used Fricke dosimetry with estimated uncertainties of 3.9% for k=1 and 1.4% for k=1, respectively. Chemical dosimetry using a standard FeSO{sub 4} solution has shown potential to be a reliable standard of absorbed dose for the HDR {sup 192}Ir source. A major uncertainty is associated with the G values reported by Fregene, which had a numerical value of 1.1 %. However, that reference provided very little detail of the experimental procedures for the {sup 192}Ir source. The G value may be obtained by using a calorimeter or ionometric measurements. In the absence of calorimetric data, this paper makes an attempt to measure the G value for the HDR {sup 192}Ir sources using ionometric measurements and recommendations from dosimetry protocols. (author)

  14. Stem effect of a Ce3+ doped SiO2 optical dosimeter irradiated with a 192Ir HDR brachytherapy source

    Fiber-optic-coupled scintillation dosimeters are characterized by their small active volume if compared to other existing systems. However, they potentially show a greater stem effect, especially in external beam radiotherapy where the Cerenkov effect is not negligible. In brachytherapy, due to the lower energies and the shorter high dose range of the employed sources, the impact of the stem effect to the detector accuracy might be low. In this work, the stem effect of a Ce3+ doped SiO2 scintillation detector coupled to a SiO2 optical fiber was studied for high dose rate brachytherapy applications. Measurements were performed in a water phantom at changing source-detector mutual positions. The same irradiations were performed with a passive optical fiber, which doesn't have the dosimeter at its end. The relative contribution of the passive fiber with respect to the uncorrected readings of the detector in each one of the investigated source dwell positions was evaluated. Furthermore, the dosimeter was calibrated both neglecting and correcting its response for the passive fiber readings. The obtained absolute dose measurements were then compared to the dose calculations resulting from the treatment planning system. Dosimeter uncertainties with and without taking into account the passive fiber readings were generally below 2.8% and 4.3%, respectively. However, a particular exception results when the source is positioned near to the optical fiber, where the detector underestimates the dose (−8%) or at source-detector longitudinal distances higher than 3 cm. The obtained results show that the proposed dosimeter might be adopted in high dose rate prostate brachytherapy with satisfactory accuracy, without the need for any stem effect correction. However, accuracy further improves by subtraction of the noise signal produced by the passive optical fiber. - Highlights: • A scintillation detector with 0.9 mm diameter was developed for in vivo dosimetry in

  15. Traceable calibration of hospital 192Ir HDR sources

    A HDR 1000 PLUS well type ionization chamber, procured from Standard Imaging, USA, and maintained by medical Physics and Safety Section (MPSS), Bhabha Atomic Research Centre (BARC), India, as a reference well chamber 1 (RWCH1), was traceably calibrated against the primary standard established by Radiological Standards Laboratory (RSL), BARC for 192Ir HDR source, in terms of air kerma strength (AKS). An indigenously developed well-type ionization chamber, reference well chamber 2 (RWCH2) and electrometer system, fabricated by CD High Tech (CDHT) Instruments Private Ltd., Bangalore, India, was in turn calibrated against RWCH1. The CDHT system (i.e. RWCH2 and CDHT electrometer system) was taken to several hospitals, in different regions of the country, to check the calibration status of 192Ir HDR sources. The result of this calibration audit work is reported here. (author)

  16. Calibration of a {sup 19} {sup 2}Ir source for high dose brachytherapy using various techniques; Calibracion de una fuente de {sup 192} Ir para braquiterapia de alta tasa de dosis mediante diversas tecnicas

    Montilla Prieto, Tedicel C., E-mail: tcdicel@gmaiLcam [Instituto de Oncologia Dr. Miguel Perez Carreno, Barbula (Venezuela, Bolivarian Republic of). Departamento de Fisica y Dosimetria; Padron Rivero, Alvaro D., E-mail: alvarodpadronr@yahoo.com.ve [Universidad de Carabobo, Barbula (Venezuela, Bolivarian Republic of). Facultad de Ciencias de la Salud. Departamento de Ciencias Fisiologicas

    2013-10-01

    In this research we studied three experimental procedures for calibration of a source of {sup 192}Ir to high dose rate for clinical brachytherapy use, and thus were compared and analysis of the advantages and disadvantages of each. For this study we quantified the value of the current kerma rate reference in air by three procedures: source calibration using a well chamber, with an cylindrical ionization chamber in air, and a cylindrical ionization chamber on a phantom, and this magnitude was compared with the value provided by the manufacturer of the source and thereby obtaining the deviation corresponding . Thus, it was found that the deviation corresponding to the source calibration making use of a well chamber, remained within tolerance, while the cylindrical ionization chamber in air and on phantom exceeded the standards established in some documents. However, although both the measurement in air and in the phantom are the procedures for the final calibration source, these can be used to verify that the delivered dose are in tolerance.

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

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

  18. A CT-based analytical dose calculation method for HDR 192Ir brachytherapy

    Purpose: This article presents an analytical dose calculation method for high-dose-rate 192Ir brachytherapy, taking into account the effects of inhomogeneities and reduced photon backscatter near the skin. The adequacy of the Task Group 43 (TG-43) two-dimensional formalism for treatment planning is also assessed. Methods: The proposed method uses material composition and density data derived from computed tomography images. The primary and scatter dose distributions for each dwell position are calculated first as if the patient is an infinite water phantom. This is done using either TG-43 or a database of Monte Carlo (MC) dose distributions. The latter can be used to account for the effects of shielding in water. Subsequently, corrections for photon attenuation, scatter, and spectral variations along medium- or low-Z inhomogeneities are made according to the radiological paths determined by ray tracing. The scatter dose is then scaled by a correction factor that depends on the distances between the point of interest, the body contour, and the source position. Dose calculations are done for phantoms with tissue and lead inserts, as well as patient plans for head-and-neck, esophagus, and MammoSite balloon breast brachytherapy treatments. Gamma indices are evaluated using a dose-difference criterion of 3% and a distance-to-agreement criterion of 2 mm. PTRANCT MC calculations are used as the reference dose distributions. Results: For the phantom with tissue and lead inserts, the percentages of the voxels of interest passing the gamma criteria (Pγ≥1) are 100% for the analytical calculation and 91% for TG-43. For the breast patient plan, TG-43 overestimates the target volume receiving the prescribed dose by 4% and the dose to the hottest 0.1 cm3 of the skin by 9%, whereas the analytical and MC results agree within 0.4%. Pγ≥1 are 100% and 48% for the analytical and TG-43 calculations, respectively. For the head-and-neck and esophagus patient plans, Pγ≥1 are ≥99

  19. Vascular brachytherapy with 90Sr/Y versus 192Ir: A health physics perspective

    Purpose: Currently there are two ongoing trials of catheter based radiation therapy in the United States, the BERT Trial (Emory University, Atlanta, GA) and the SCRIPPS Trial (Scripps Clinic, La Jolla, CA). The BERT method involved the use of a treatment system to manually deliver a source train consisting of 12, encapsulated 90Sr/Y seeds of 3 cm total active length. The total activity of the source train was approximately 3.7 GBq. The SCRIPPS trial involved the use of a hand delivered 192Ir (BEST Industries) source train of either 5 or 9 sources with 1 mm spacing between the sources. The average total activity of the source train was 3.6 GBq ± 1.08 GBq. It is the purpose of this study to compare the patient dose and staff exposures from the above source trains. A comparison with exposures from use of fluoroscopy in the catheterization laboratory will also be made. Materials and Methods: Measurements made with a GM meter at specified locations around the BERT patients during the insertion of the seeds were compared with published information from the SCRIPPS Trial. Monte Carlo modeled measurements of the equivalent dose in humans from insertion of the source trains were also compared for both methods. The above were contrasted with GM measurements from use of fluoroscopy in the catheterization laboratory. Results: Average exposure rates recorded at the patient's chest and groin from the BERT method were 4.9x10-4 and 1.29x10-4 C/kg·hr respectively. Average exposures to the operator from the BERT method and the SCRIPPS method were 8.6x10-6 and 1.03x10-3 C/kg respectively. A typical exposure rate for conventional cardiac fluoroscopy is 3.9x10-3 C/kg·hr. Monte Carlo modeled calculations of patient dose equivalent for the BERT method and the SCRIPPS method were 0.43 μSv and 6.41 mSv respectively. Conclusions: Vascular brachytherapy performed with 90Sr/Y sources resulted in staff exposures of at least a factor of 120 less and patient doses of a factor of nearly 15

  20. Evaluation of PC-ISO for customized, 3D Printed, gynecologic 192-Ir HDR brachytherapy applicators.

    Cunha, J Adam M; Mellis, Katherine; Sethi, Rajni; Siauw, Timmy; Sudhyadhom, Atchar; Garg, Animesh; Goldberg, Ken; Hsu, I-Chow; Pouliot, Jean

    2015-01-01

    The purpose of this study was to evaluate the radiation attenuation properties of PC-ISO, a commercially available, biocompatible, sterilizable 3D printing material, and its suitability for customized, single-use gynecologic (GYN) brachytherapy applicators that have the potential for accurate guiding of seeds through linear and curved internal channels. A custom radiochromic film dosimetry apparatus was 3D-printed in PC-ISO with a single catheter channel and a slit to hold a film segment. The apparatus was designed specifically to test geometry pertinent for use of this material in a clinical setting. A brachytherapy dose plan was computed to deliver a cylindrical dose distribution to the film. The dose plan used an 192Ir source and was normalized to 1500 cGy at 1 cm from the channel. The material was evaluated by comparing the film exposure to an identical test done in water. The Hounsfield unit (HU) distributions were computed from a CT scan of the apparatus and compared to the HU distribution of water and the HU distribution of a commercial GYN cylinder applicator. The dose depth curve of PC-ISO as measured by the radiochromic film was within 1% of water between 1 cm and 6 cm from the channel. The mean HU was -10 for PC-ISO and -1 for water. As expected, the honeycombed structure of the PC-ISO 3D printing process created a moderate spread of HU values, but the mean was comparable to water. PC-ISO is sufficiently water-equivalent to be compatible with our HDR brachytherapy planning system and clinical workflow and, therefore, it is suitable for creating custom GYN brachytherapy applicators. Our current clinical practice includes the use of custom GYN applicators made of commercially available PC-ISO when doing so can improve the patient's treatment.  PMID:25679174

  1. Qualification tests for {sup 192}Ir sealed sources

    Iancso, Georgeta, E-mail: georgetaiancso@yahoo.com; Iliescu, Elena, E-mail: georgetaiancso@yahoo.com; Iancu, Rodica, E-mail: georgetaiancso@yahoo.com [National Institute of R and D for Physics and Nuclear Engineering Horia Hulubei, Magurele (Romania)

    2013-12-16

    This paper describes the results of qualification tests for {sup 192}Ir sealed sources, available in Testing and Nuclear Expertise Laboratory of National Institute for Physics and Nuclear Engineering 'Horia Hulubei' (I.F.I.N.-HH), Romania. These sources had to be produced in I.F.I.N.-HH and were tested in order to obtain the authorization from The National Commission for Nuclear Activities Control (CNCAN). The sources are used for gammagraphy procedures or in gammadefectoscopy equipments. Tests, measurement methods and equipments used, comply with CNCAN, AIEA and International Quality Standards and regulations. The qualification tests are: 1. Radiological tests and measurements: dose equivalent rate at 1 m; tightness; dose equivalent rate at the surface of the transport and storage container; external unfixed contamination of the container surface. 2. Mechanical and climatic tests: thermal shock; external pressure; mechanic shock; vibrations; boring; thermal conditions for storage and transportation. Passing all tests, it was obtained the Radiological Security Authorization for producing the {sup 192}Ir sealed sources. Now IFIN-HH can meet many demands for this sealed sources, as the only manufacturer in Romania.

  2. The contribution from transit dose for 192Ir HDR brachytherapy treatments

    Fonseca, G. P.; Landry, G.; Reniers, B.; Hoffmann, A.; Rubo, R. A.; Antunes, P. C. G.; Yoriyaz, H.; Verhaegen, F.

    2014-04-01

    Brachytherapy treatment planning systems that use model-based dose calculation algorithms employ a more accurate approach that replaces the TG43-U1 water dose formalism and adopt the TG-186 recommendations regarding composition and geometry of patients and other relevant effects. However, no recommendations were provided on the transit dose due to the source traveling inside the patient. This study describes a methodology to calculate the transit dose using information from the treatment planning system (TPS) and considering the source's instantaneous and average speed for two prostate and two gynecological cases. The trajectory of the 192Ir HDR source was defined by importing applicator contour points and dwell positions from the TPS. The transit dose distribution was calculated using the maximum speed, the average speed and uniform accelerations obtained from the literature to obtain an approximate continuous source distribution simulated with a Monte Carlo code. The transit component can be negligible or significant depending on the speed profile adopted, which is not clearly reported in the literature. The significance of the transit dose can also be due to the treatment modality; in our study interstitial treatments exhibited the largest effects. Considering the worst case scenario the transit dose can reach 3% of the prescribed dose in a gynecological case with four catheters and up to 11.1% when comparing the average prostate dose for a case with 16 catheters. The transit dose component increases by increasing the number of catheters used for HDR brachytherapy, reducing the total dwell time per catheter or increasing the number of dwell positions with low dwell times. This contribution may become significant (>5%) if it is not corrected appropriately. The transit dose cannot be completely compensated using simple dwell time corrections since it may have a non-uniform distribution. An accurate measurement of the source acceleration and maximum speed should be

  3. The contribution from transit dose for 192Ir HDR brachytherapy treatments

    Brachytherapy treatment planning systems that use model-based dose calculation algorithms employ a more accurate approach that replaces the TG43-U1 water dose formalism and adopt the TG-186 recommendations regarding composition and geometry of patients and other relevant effects. However, no recommendations were provided on the transit dose due to the source traveling inside the patient. This study describes a methodology to calculate the transit dose using information from the treatment planning system (TPS) and considering the source's instantaneous and average speed for two prostate and two gynecological cases. The trajectory of the 192Ir HDR source was defined by importing applicator contour points and dwell positions from the TPS. The transit dose distribution was calculated using the maximum speed, the average speed and uniform accelerations obtained from the literature to obtain an approximate continuous source distribution simulated with a Monte Carlo code. The transit component can be negligible or significant depending on the speed profile adopted, which is not clearly reported in the literature. The significance of the transit dose can also be due to the treatment modality; in our study interstitial treatments exhibited the largest effects. Considering the worst case scenario the transit dose can reach 3% of the prescribed dose in a gynecological case with four catheters and up to 11.1% when comparing the average prostate dose for a case with 16 catheters. The transit dose component increases by increasing the number of catheters used for HDR brachytherapy, reducing the total dwell time per catheter or increasing the number of dwell positions with low dwell times. This contribution may become significant (>5%) if it is not corrected appropriately. The transit dose cannot be completely compensated using simple dwell time corrections since it may have a non-uniform distribution. An accurate measurement of the source acceleration and maximum speed

  4. Monte Carlo estimation of dose difference in lung from 192Ir brachytherapy due to tissue inhomogeneity

    Lung brachytherapy using high-dose rate 192Ir technique is a well-established technique of radiation therapy. However, many commercial treatment planning systems do not have the ability to consider the inhomogeneity of lung in relation to normal tissue. Under such circumstances dose calculations for tissues and organs at risk close to the target are inaccurate. The purpose of the current study was to estimate the dose difference due to tissue inhomogeneity using the Monte Carlo simulation code MCNP-5. Results showed that there was a relative sub dosage by treatment planning systems calculations in neighbouring tissues around the radioactive source due to inhomogeneity ignorance. The presence of lung instead of normal tissue resulted in an increase in relative dose, which approached 8 % at 4-cm distance from the source. Additionally, the relative increase was small for the lung (2.1 %) and larger for organs at risk such as the heart (6.8 %) and bone marrow (7.6 %). (authors)

  5. Influence of the 192Ir source decay on biological effect

    Biological effect of the 192Ir high activity source on LA795 tumor of mice and HCT-8 cells have been investigated when decay of the source power from 340.4 GBq to 81.4 GBq no marked difference was found between the two cell survival curves of HCT-8 cells and both of them compared with that of the X-ray irradiation the value of relative biological effect (0.1 survival) was 0.43. On the experiment of tumor LA795 of mice, when the source power was 293.3 GBq and 96.2 GBq, no different biological effect can be seen between the two series of figures. The relative biological effect was 0.55-0.60 (tumor growth delay) comparing with those of X-ray irradiation

  6. Calculation of dose decrease in a finite phantom of a 192Ir point source

    The purpose of this study was to calculate the dose decrease in a finite phantom of a 192Ir-point source by using a new algorithm based on field theory. The methods used included the phenomenological application of the principle ''mirror image of an electric point source in front of a dielectric semi-plateau'' to a radioactive source in a finite phantom results in a function to calculate the dose decrease near the surface. Measurements were done in a water phantom in three different experimental setups. To verify the calculated results Monte Carlo (MC) simulations of dose distribution of a 192Ir point source in 34x40x40 cm3 water were carried out. The strength of mirror source was found -0.103 of the real source. A lack scatter function was necessary to handle the dose decrease very close to surface. The measured and calculated dose values differed less than 0.9%. Both MC simulations and the new algorithm show the dose decrease near phantom surface with differences less than 2% between each other. The new algorithm based on field theory calculated the dose decrease of a 192Ir point source in a finite phantom with a very good agreement to measured and simulated data. A clinical example, which affects only a single planar boundary, is given by using molds in the treatment of skin tumors. This was calculated with the new algorithm presented in this article. The comparison with the common algorithm demonstrates the differences that might cause an overestimation of the dose, which probably leads an underdosing of the tumor. The general use of the new algorithm in brachytherapy where a variety of boundary shapes are encountered has to be verified seriously

  7. Air kerma rate measurements of 192Ir source in Gammamed 12i HDR/PDR unit using well type ionization chamber

    The use of high dose rate (HDR) brachytherapy in radiotherapy department has increased nowadays. The initial activity of 192Ir sources, used in high dose rate brachytherapy unit is approximately 10 Ci. About 3 to 4 times per year, a replacement is made of these sources, because of the decay half-life of 192Ir with 73.83 days. It is recommended that each time a new HDR source is installed for use in clinical routine, a source calibration in the hospital should be carried out

  8. Microdosimetric spread for cell-sized targets exposed to 60Co, 192Ir and 125I sources

    The magnitude of the spread in specific energy deposition per cell may be a confounding factor in dose- response analysis motivating derivation of explicit data for the most common brachytherapy isotopes 125I and 192Ir, and for 60Co radiation frequently used as reference in RBE studies. The aim of this study is to analyse the microdosimetric spread as given by the frequency distribution of specific energy for a range of doses imparted by 125I, 192Ir and 60Co sources. An upgraded version of the Monte Carlo code PENELOPE was used for scoring energy deposition distributions in liquid water for each of the radiation qualities. Frequency distributions of specific energy were calculated according to the formalism of Kellerer and Chmelevsky. Results indicate that the magnitude of the microdosimetric spread increases with decreasing target size and decreasing energy of the radiation quality. Within the clinical relevant dose range (1 to 100 Gy), the spread does not exceed 4 % for 60Co, 5 % for 192Ir and 6 % for 125I. The frequency distributions can be accurately approximated with symmetrical normal distributions at doses down to 0.2 Gy for 60Co, 0.1 Gy for 192Ir and 0.08 Gy for 125I. (authors)

  9. HDR {sup 192}Ir source speed measurements using a high speed video camera

    Fonseca, Gabriel P. [Instituto de Pesquisas Energéticas e Nucleares—IPEN-CNEN/SP, São Paulo 05508-000, Brazil and Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Viana, Rodrigo S. S.; Yoriyaz, Hélio [Instituto de Pesquisas Energéticas e Nucleares—IPEN-CNEN/SP, São Paulo 05508-000 (Brazil); Podesta, Mark [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Rubo, Rodrigo A.; Sales, Camila P. de [Hospital das Clínicas da Universidade de São Paulo—HC/FMUSP, São Paulo 05508-000 (Brazil); Reniers, Brigitte [Department of Radiation Oncology - MAASTRO, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Research Group NuTeC, CMK, Hasselt University, Agoralaan Gebouw H, Diepenbeek B-3590 (Belgium); Verhaegen, Frank, E-mail: frank.verhaegen@maastro.nl [Department of Radiation Oncology - MAASTRO, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Medical Physics Unit, Department of Oncology, McGill University, Montréal, Québec H3G 1A4 (Canada)

    2015-01-15

    Purpose: The dose delivered with a HDR {sup 192}Ir afterloader can be separated into a dwell component, and a transit component resulting from the source movement. The transit component is directly dependent on the source speed profile and it is the goal of this study to measure accurate source speed profiles. Methods: A high speed video camera was used to record the movement of a {sup 192}Ir source (Nucletron, an Elekta company, Stockholm, Sweden) for interdwell distances of 0.25–5 cm with dwell times of 0.1, 1, and 2 s. Transit dose distributions were calculated using a Monte Carlo code simulating the source movement. Results: The source stops at each dwell position oscillating around the desired position for a duration up to (0.026 ± 0.005) s. The source speed profile shows variations between 0 and 81 cm/s with average speed of ∼33 cm/s for most of the interdwell distances. The source stops for up to (0.005 ± 0.001) s at nonprogrammed positions in between two programmed dwell positions. The dwell time correction applied by the manufacturer compensates the transit dose between the dwell positions leading to a maximum overdose of 41 mGy for the considered cases and assuming an air-kerma strength of 48 000 U. The transit dose component is not uniformly distributed leading to over and underdoses, which is within 1.4% for commonly prescribed doses (3–10 Gy). Conclusions: The source maintains its speed even for the short interdwell distances. Dose variations due to the transit dose component are much lower than the prescribed treatment doses for brachytherapy, although transit dose component should be evaluated individually for clinical cases.

  10. HDR 192Ir source speed measurements using a high speed video camera

    Purpose: The dose delivered with a HDR 192Ir afterloader can be separated into a dwell component, and a transit component resulting from the source movement. The transit component is directly dependent on the source speed profile and it is the goal of this study to measure accurate source speed profiles. Methods: A high speed video camera was used to record the movement of a 192Ir source (Nucletron, an Elekta company, Stockholm, Sweden) for interdwell distances of 0.25–5 cm with dwell times of 0.1, 1, and 2 s. Transit dose distributions were calculated using a Monte Carlo code simulating the source movement. Results: The source stops at each dwell position oscillating around the desired position for a duration up to (0.026 ± 0.005) s. The source speed profile shows variations between 0 and 81 cm/s with average speed of ∼33 cm/s for most of the interdwell distances. The source stops for up to (0.005 ± 0.001) s at nonprogrammed positions in between two programmed dwell positions. The dwell time correction applied by the manufacturer compensates the transit dose between the dwell positions leading to a maximum overdose of 41 mGy for the considered cases and assuming an air-kerma strength of 48 000 U. The transit dose component is not uniformly distributed leading to over and underdoses, which is within 1.4% for commonly prescribed doses (3–10 Gy). Conclusions: The source maintains its speed even for the short interdwell distances. Dose variations due to the transit dose component are much lower than the prescribed treatment doses for brachytherapy, although transit dose component should be evaluated individually for clinical cases

  11. Air kerma strength calibration of 0.6 cc Farmer chamber for 192Ir HDR source

    One of the methods adopted by hospitals for the calibration of the HDR 192Ir source, in terms of Air Kerma Strength (AKS) is to use 0.6cc chamber at short source to chamber distances for measuring the air kerma rate at the chamber position and then compute the AKS using the appropriate correction factors. However, the 0.6 cc Farmer type chambers purchased by the users for the calibration of the HDR 192Ir source, are not generally provided with an HDR 192Ir calibration factor. With the result, many hospitals that have purchased the Farmer type chamber for the calibration of 192Ir HDR sources, use the 60Co calibration factor for this purpose. The use of 60Co calibration factor for the 192Ir HDR source would unnecessarily increase the uncertainty of the measured AKS. Again, because of the low chamber sensitivity, hospitals often use, source to chamber distances as small as a few cm for calibrating the 192Ir HDR source. In the absence of a rigid source-chamber positioning system, this can lead to several percent errors in AKS determination. Also, hospitals often don't take into account corrections for the room scatter or the fluence non-uniformity across the chamber, which further increase the uncertainty of the measured AKS

  12. Comparison of air-kerma strength determinations for HDR 192Ir sources

    Purpose: To perform a comparison of the interim air-kerma strength standard for high dose rate (HDR) 192Ir brachytherapy sources maintained by University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) with measurements of the various source models using modified techniques from the literature. The current interim standard was established by Goetsch et al. in 1991 and has remained unchanged to date. Methods: The improved, laser-aligned seven-distance apparatus of University of Wisconsin Medical Radiation Research Center (UWMRRC) was used to perform air-kerma strength measurements of five different HDR 192Ir source models. The results of these measurements were compared with those from well chambers traceable to the original standard. Alternative methodologies for interpolating the 192Ir air-kerma calibration coefficient from the NIST air-kerma standards at 137Cs and 250 kVp x rays (M250) were investigated and intercompared. As part of the interpolation method comparison, the Monte Carlo code EGSnrc was used to calculate updated values of Awall for the Exradin A3 chamber used for air-kerma strength measurements. The effects of air attenuation and scatter, room scatter, as well as the solution method were investigated in detail. Results: The average measurements when using the inverse NK interpolation method for the Classic Nucletron, Nucletron microSelectron, VariSource VS2000, GammaMed Plus, and Flexisource were found to be 0.47%, -0.10%, -1.13%, -0.20%, and 0.89% different than the existing standard, respectively. A further investigation of the differences observed between the sources was performed using MCNP5 Monte Carlo simulations of each source model inside a full model of an HDR 1000 Plus well chamber. Conclusions: Although the differences between the source models were found to be statistically significant, the equally weighted average difference between the seven-distance measurements and the well chambers was 0.01%, confirming that it is

  13. High-Dose-Rate 192Ir Brachytherapy Dose Verification: A Phantom Study

    Alireza Nikoofar

    2015-05-01

    Full Text Available Background: The high-dose-rate (HDR brachytherapy might be an effective tool for palliation of dysphagia. Because of some concerns about adverse effects due to absorbed radiation dose, it is important to estimate absorbed dose in risky organs during this treatment. Objectives: This study aimed to measure the absorbed dose in the parotid, thyroid, and submandibular gland, eye, trachea, spinal cord, and manubrium of sternum in brachytherapy in an anthropomorphic phantom. Materials and Methods: To measure radiation dose, eye, parotid, thyroid, and submandibular gland, spine, and sternum, an anthropomorphic phantom was considered with applicators to set thermoluminescence dosimeters (TLDs. A specific target volume of about 23 cm3 in the upper thoracic esophagus was considered as target, and phantom planned computed tomography (CT for HDR brachytherapy, then with a micro-Selectron HDR (192Ir remote after-loading unit. Results: Absorbed doses were measured with calibrated TLDs and were expressed in centi-Gray (cGy. In regions far from target (≥ 16 cm such as submandibular, parotid and thyroid glands, mean measured dose ranged from 1.65 to 5.5 cGy. In closer regions (≤ 16 cm, the absorbed dose might be as high as 113 cGy. Conclusions: Our study showed similar depth and surface doses; in closer regions, the surface and depth doses differed significantly due to the role of primary radiation that had imposed a high-dose gradient and difference between the plan and measurement, which was more severe because of simplifications in tissue inhomogeneity, considered in TPS relative to phantom.

  14. Evaluation of radiation dose on people adjacent to implant patients during brachytherapy for prostate cancer using {sup 192}Ir

    Kim, Jung Hoon; Ko, Seong Jin; Kang, Se Sik; Kim, Chang Soo [Catholic University, Busan (Korea, Republic of)

    2009-10-15

    The incidence of prostate cancer is rapidly increasing due to aging of the population and westernization of dietary habits, etc. As a result, the frequency of prostate cancer has become the fifth highest among all male cancers and the first among urological cancers. Brachytherapy is commonly used for locally progressing prostate cancers. Since the mid 1980s, therapies using radio-isotopes, such as low-invasive {sup 125}I, {sup 103}Pd and {sup 192}Ir, have been widely performed in the U.S. and Europe. However, brachytherapy involves implanting radio-isotopes into the human body which is of concern because it may expose the health care professionals administering the therapy to unnecessary radiation. Accordingly, this study intends to predict the radiation dose that people adjacent to patients implanted with a radio-isotope are exposed to during prostate cancer radiation therapy by using a mathematical anthropomorphic phantom and {sup 192}Ir.

  15. Evaluation of radiation dose on people adjacent to implant patients during brachytherapy for prostate cancer using 192Ir

    The incidence of prostate cancer is rapidly increasing due to aging of the population and westernization of dietary habits, etc. As a result, the frequency of prostate cancer has become the fifth highest among all male cancers and the first among urological cancers. Brachytherapy is commonly used for locally progressing prostate cancers. Since the mid 1980s, therapies using radio-isotopes, such as low-invasive 125I, 103Pd and 192Ir, have been widely performed in the U.S. and Europe. However, brachytherapy involves implanting radio-isotopes into the human body which is of concern because it may expose the health care professionals administering the therapy to unnecessary radiation. Accordingly, this study intends to predict the radiation dose that people adjacent to patients implanted with a radio-isotope are exposed to during prostate cancer radiation therapy by using a mathematical anthropomorphic phantom and 192Ir

  16. Assessment of Absorbed Dose in Persons close to the Patients during 192Ir brachytherapy for Cervical Cancer

    According to the 2007 Annual Report of the National Cancer Registry, cervical cancer showed an occurring frequency of 7th in female cancers and 4rd in females with an age of 35-64 years. Both radiotherapy and chemotherapy are mainly used for the treatment of cervical cancer. In case of radiotherapy, brachytherapy using radioisotopes in conjunction with external-beam radiation therapy (EBRT) using a linear accelerator is used in most cases to improve the outcome of cancer treatment. Brachytherapy, one of the cervical cancer radiotherapies, is a method that can minimize the damage of normal tissues restricting absorbed dose to uterus. It is, however, necessary to conduct a quantitative assessment on brachytherapy because it may cause radiation exposure to medical care providers during the radiotherapy. Therefore, the study provides the basic research data regarding brachytherapy for cervical cancer, estimating the absorbed dose in persons close to the patients using a mathematical phantom during 192Ir brachytherapy for cervical cancer

  17. Characterization of TLD-100 in powders for dosimetric quality control of {sup 192} Ir sources used in brachytherapy of high dose rate; Caracterizacion de TLD-100 en polvo para control de calidad dosimetrico de fuentes de Ir{sup 192} usadas en braquiterapia de alta tasa de dosis

    Loaiza C, S.P

    2007-07-01

    The Secondary Standard Dosimetric at the National Institute of Nuclear Research (ININ) calibrated a lot of powdered TLD-100 (LiF:Mg,Ti) in terms of absorbed dose to water D{sub w} for the energy of: {sup 60}Co, {sup 137C}s, X rays of 250 and 50 kVp. Later on, it is carried out an interpolation of the calibration for the energy of the {sup 192}Ir. This calibration is part of a dosimetric quality control program, to solve the problems of traceability for the measurements carried out by the users of {sup 192}Ir sources employed in the treatments of High Dose Rate Brachytherapy (HDR) at the Mexican Republic. The calibrations of the radiation beams are made with the following protocols: IAEA TRS-398 for the {sup 60}Co for D{sub w}, using a secondary standard ionization chamber PTW N30013 calibrated in D{sub w} by the National Research Council (NRC, Canada). AAPM TG-43 for D{sub w} in terms of the strength kerma Sk, calibrating this last one quantity for the {sup 137}Cs radioactive source, with a well chamber HDR 1000 PLUS traceable to the University of Wisconsin (US). AAPM TG-61 for X ray of 250 and 50 kVp for D{sub w} start to Ka using field standard a Farmer chamber PTW 30001 traceable to K for the Central Laboratory of Electric Industries (CLEI, France). The calibration curves (CC) they built for the response of the powder TLD: R{sub TLD} vs D{sub w}: For the energy of {sup 60}Co, {sup 137}Cs, X rays of 250 and 50 kVp. Fitting them with the least square method weighed by means of a polynomial of second grade that corrects the supra linearity of the response. iii. Each one of the curves was validated with a test by lack of fitting and for the Anderson Darling normality test, using the software MINITAB in both cases. iv. The sensibility factor (F{sub s}) for each energy corresponds to the slope of the CC, v. The F{sub s} for the two {sup 192}Ir sources used are interpolated: one for a Micro Selectron source and the other one a Vari Source source. Finally, a couple of

  18. Calibration of Gammamed 12i 192Ir high dose rate source

    High-dose-rate (HDR) brachytherapy has been used in our department for cancer treatment for about three years. The HDR 192Ir source is usually calibrated using a well-type ionisation chamber or a thimble chamber free in air. This paper presents the calibration of 11 sources using Standard Imaging HDR1000 well chamber. We investigated the effect of location of the chamber in the room and scatter environment on output ionisation current and determined the most sensitive measurement point in the chamber. The largest discrepancy between the measured air kerma rate (AKR) and manufacturer's specification was 3.4%.These results were compared with calibration in the air done using the 0.6 ccm Farmer-type chamber, attached to a special lightweight holder. Instead of interpolative techniques recommended by either the IAEA or authorised laboratories, we used a calibration coefficient for 60Co quality only. Beside the conventional electrometer/chamber corrections, the exposure gradient corrections due to the finite dimensions of the chamber were employed. The influence of room scatter was also estimated. Preliminary results of calibration in air indicated that well chamber calibration and Farmer chamber calibration with 60Co calibration factor were within 2%.(author)

  19. Interstitial brachytherapy for carcinoma of the base of tongue using a high dose rate 192Ir remote afterloader

    We have applied an interstitial brachytherapy employing a high dose rate 192Ir remote afterloader to five patients with cancer of the base of tongue since December 1994. Insertion of applicators was carried out with tracheotomy under general anesthesia. Brachytherapy was delivered twice a day with a 6-hour interval. Irradiation dose was estimated at the point of 5 mm from outer applicators. HDR brachytherapy was well tolerated for 4-5 days in all patients and acute radiation reaction was minimal. Local control were observed in two cases. In conclusion, our preliminary experience suggests that HDR brachytherapy may be an option in the radiotherapy for carcinoma of the base of tongue. Optimal dose-fractionation protocol should be established. (author)

  20. Correction factors for Farmer-type chambers for absorbed dose determination in 60Co and 192Ir brachytherapy dosimetry

    This paper presents experimentally determined correction factors for Farmer-type chambers for absorbed dose determination in 60Co and 192Ir brachytherapy dosimetry. The correction factors were determined from measurements made in a PMMA phantom and calculation of ratios of measured charges. The ratios were corrected for the different volumes of the ionization chambers, determined in external high-energy electron beams. The correction factors for the central electrode effect and the wall material dependency in 60Co brachytherapy dosimetry agree with those used in external 60Co beam dosimetry. In 192Ir dosimetry, the central aluminium electrode increases the response of an NE2571 chamber compared with that of a chamber with a central graphite electrode. The increase is 1.1 and 2.1% at 1.5 and 5.0 g cm-2 distance, respectively. Similar values are obtained with an NE2577 chamber. The wall correction factor in 192Ir dosimetry for a chamber with an A-150 wall has been determined to be 1.018, independent of the measurement distance. For a graphite walled chamber, the correction factor is 0.996 and 1.001 at 1.5 and 5.0 g cm-2 distance, respectively. The values of the wall correction factors are evaluated by a theory presented. If the chamber is used according to the 'large cavity' principle, the correction factor to account for the replacement of the phantom material by the ionization chamber was determined to be 0.982 for an NE2571 chamber when used with a Delrin cap, and 0.978 for an NE2581 when used with a polystyrene cap. The correction factors for the 'large cavity' principle are valid at both 60Co and 192Ir qualities. (author)

  1. Effects of Endovascular Brachytherapy with 192Ir Afterloading System on Expression of Type Ⅰ Collagen after Angioplasty

    向定成; 杨传红; 候友贤; 龚志华; 易绍东; 邱建

    2003-01-01

    Objectives To investi-gate the effect and mechanism of endovascularbrachytherapy with 192Ir on expression of type Ⅰ collagen, metalloproteinases - 1 (MMP - 1) and the tissueinhibitor (TIMP- 1 ) after angioplasty. MethodsRestenotic model of domestic microswine was em-ployed and the iliac arteries were randomized to radi-ation group ( n = 12), which were treated with 20 ~ 25Gy of 192Ir, and non - radiation group ( n = 36) afterangioplasty. The target vessels were harvested in theend of 3 months and 6 months after angioplasty. Im-munohistochemistry and in situ hybridization were usedto detect proteins of type Ⅰ collagen, MMP-1 andTIMP- 1, and mRNA expression of type Ⅰ collagen.Results The protein and mRNA of type Ⅰ collagen,the ratios of TIMP-1/MMP-1 were significantlylower iu radiation group than in non- radiation group( P < 0.05 or 0.01 ). The peak of transcription of typeⅠ collagen mRNA was at 6 months and 3 months in non-radiation group and radiation group respectively.Conclusions Endovascular brachytherapy with192Ir might modify the metabolism of extracellular ma-trix after angioplasty by inhibiting the synthesis of typeⅠ collagen and the activities of MMP - 1 and TIMP - 1.

  2. Production of 198Au and 192Ir sources for cancer therapy

    Radiation sources of 198Au and 192Ir in various types have been developed for cancer therapy, which are '198Au grains' and 'hairpin, single pin, thin wire, seed and seed assembly of 192Ir'. The products are being supplied to a number of cancer clinics in Japan. As target materials, gold metal and iridium/platinum alloy were used; iridium/platinum alloy gives flexibility to products and reduces pains in the patients. Grains and wires of the target materials were of platinum covered, and irradiated in the JRR-2 or JRR-4 reactor. The platinum cover absorbs the β rays of 198Au and 192Ir, which are not effective for cancer therapy. The neutron irradiation conditions were controlled to produce the following radioactivities: The 198Au grains are 185 MBq each at the time to be used in clinics, the 192Ir source radioactivities were, assayed at the time of shipment, 740 MBq each for the hairpin, 370 MBq for the single pin, 37 MBq for the seed, a radioactivity equivalent to 37 MBq multiplied by the number of seeds loaded for the seed assembly, and 148 MBq, 222 MBq or 370 MBq for the thin wire. There has been confirmed neither significant contamination of other radioactivities nor ununiformity of the radioactivity in the wire source. The radioactivities of products have been kept within ± 5% of an averaged value, except for the seed. For producing the seed assemblies, neutron irradiated seed and spacer teflon wires are loaded one by one into a teflon tube. This loading process and the measurement of radioactivities were automated to meet increased demands. In fiscal year 1989, the 198Au grains were produced in 48 batches and 2570 pieces were shipped and the 192Ir sources were produced in 39 batches and 4852 pieces were delivered, meeting all domestic demands. Being accompanied with the documents related to the production process, the present report is also usable as a production manual. (author)

  3. Dosimetric verification of source strength for HDR afterloading units with 192Ir- and 60Co- photon sources: comparison of three different international protocols

    Before clinical use of a brachytherapy source, regulations or recommendations by medical physics societies require an independent measurement of its air kerma strength by a qualified medical physicist. Currently, in addition to 192Ir, also HDR-60Co sources are increasingly coming into operation. However, the existing dosimetry protocols do not provide any guidelines for 60Co sources. The purpose of this work was therefore to compare air Kerma rate measurements as recommended by different dosimetry protocols for 192Ir HDR sources and to test their applicability to 60Co sources. Dosimetric verification of HDR afterloading source specification was performed according to three protocols, DIN 6809-2 (1993) in combination with DGMP-Report 13 (2006), IAEA-TECDOC-1274 (2002) and AAPM Report 41 (1993) for the nuclides 192Ir and 60Co. Measurements of the sources reference air kerma rate were performed with 3 different methods (with a cylindrical chamber both in a solid phantom and in free air, and with a well chamber) and evaluated using all three protocols for each type of source and method of measurement. The measurements with all protocols and methods show deviations from the certified specification smaller than about 1.2% for 192Ir and 2.5% for 60Co sources. The measurements with the well chamber showed the lowest deviations from the certificate value. Air kerma rate measurements for 60Co HDR sources using the existing protocols are possible with accuracy sufficient to verify source calibration as provided by the source certificate. However, extension of the protocols by correction factors for measurement with 60Co sources would be helpful. (author)

  4. The mean photon energy ĒF at the point of measurement determines the detector-specific radiation quality correction factor kQ,M in (192)Ir brachytherapy dosimetry.

    Chofor, Ndimofor; Harder, Dietrich; Selbach, Hans-Joachim; Poppe, Björn

    2016-09-01

    The application of various radiation detectors for brachytherapy dosimetry has motivated this study of the energy dependence of radiation quality correction factor kQ,M, the quotient of the detector responses under calibration conditions at a (60)Co unit and under the given non-reference conditions at the point of measurement, M, occurring in photon brachytherapy. The investigated detectors comprise TLD, radiochromic film, ESR, Si diode, plastic scintillator and diamond crystal detectors as well as ionization chambers of various sizes, whose measured response-energy relationships, taken from the literature, served as input data. Brachytherapy photon fields were Monte-Carlo simulated for an ideal isotropic (192)Ir point source, a model spherical (192)Ir source with steel encapsulation and a commercial HDR GammaMed Plus source. The radial source distance was varied within cylindrical water phantoms with outer radii ranging from 10 to 30cm and heights from 20 to 60cm. By application of this semiempirical method - originally developed for teletherapy dosimetry - it has been shown that factor kQ,M is closely correlated with a single variable, the fluence-weighted mean photon energy ĒF at the point of measurement. The radial profiles of ĒF obtained with either the commercial (192)Ir source or the two simplified source variants show little variation. The observed correlations between parameters kQ,M and ĒF are represented by fitting formulae for all investigated detectors, and further variation of the detector type is foreseen. The herewith established close correlation of radiation quality correction factor kQ,M with local mean photon energy ĒF can be regarded as a simple regularity, facilitating the practical application of correction factor kQ,M for in-phantom dosimetry around (192)Ir brachytherapy sources. ĒF values can be assessed by Monte Carlo simulation or measurement. A technique describing the local measurement of ĒF will be published separately. PMID

  5. The influence of different 192Ir sources geometries to the energy deposition

    In this paper, various simplifications of the HDR source Varian VariSource Classic model, in which 192Ir as a radionuclide is used, were compared. These simplifications were carried out by the simulation of Monte Carlo, using the MCNPX code. The different sources were compared through a distribution of energy deposition in a water phantom. Our results indicated that small simplifications will present no influence on the source response, and the removal of the entire capsule surrounding the radionuclide will present a difference of just 0.51% in the final response. (author)

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

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

  7. Experimental 3D dosimetry around a high-dose-rate clinical 192Ir source using a polyacrylamide gel (PAG) dosimeter

    It is well known that the experimental dosimetry of brachytherapy sources presents a challenge. Depending on the particular dosimeter used, measurements can suffer from poor spatial resolution (ion chambers), lack of 3D information (film) or errors due to the presence of the dosimeter itself distorting the radiation flux. To avoid these problems, we have investigated the dosimetry of a clinical 192Ir source using a polyacrylamide gel (PAG) dosimeter. Experimental measurements of dose versus radial distance from the centre of the source (cross-line plots) were compared with calculations produced with a Nucletron NPS planning system. Good agreement was found between the planning system and gel measurements in planes selected for analysis. Gel dosimeter measurements in a coronal plane through the phantom showed a mean difference between measured absorbed dose and calculated dose of 0.17 Gy with SD=0.13Gy. Spatially, the errors at the reference point remain within one image pixel (1.0 mm). The use of polymer gel dosimetry shows promise for brachytherapy applications, offering complete, three-dimensional dose information, good spatial resolution and small measurement errors. Measurements close to the source, however, are difficult, due to some of the limiting properties of the polyacrylamide gel. (author)

  8. Dose specification for 192Ir high dose rate brachytherapy in terms of dose-to-water-in-medium and dose-to-medium-in-medium

    Paiva Fonseca, Gabriel; Carlsson Tedgren, Åsa; Reniers, Brigitte; Nilsson, Josef; Persson, Maria; Yoriyaz, Hélio; Verhaegen, Frank

    2015-06-01

    Dose calculation in high dose rate brachytherapy with 192Ir is usually based on the TG-43U1 protocol where all media are considered to be water. Several dose calculation algorithms have been developed that are capable of handling heterogeneities with two possibilities to report dose: dose-to-medium-in-medium (Dm,m) and dose-to-water-in-medium (Dw,m). The relation between Dm,m and Dw,m for 192Ir is the main goal of this study, in particular the dependence of Dw,m on the dose calculation approach using either large cavity theory (LCT) or small cavity theory (SCT). A head and neck case was selected due to the presence of media with a large range of atomic numbers relevant to tissues and mass densities such as air, soft tissues and bone interfaces. This case was simulated using a Monte Carlo (MC) code to score: Dm,m, Dw,m (LCT), mean photon energy and photon fluence. Dw,m (SCT) was derived from MC simulations using the ratio between the unrestricted collisional stopping power of the actual medium and water. Differences between Dm,m and Dw,m (SCT or LCT) can be negligible (brachytherapy studies clearly report the dose quantity. It further shows that while differences between Dm,m and Dw,m (SCT) mainly depend on tissue type, differences between Dm,m and Dw,m (LCT) are, in addition, significantly dependent on the local photon energy fluence spectrum which varies with distance to implanted sources.

  9. Accuracy of applicator tip reconstruction in MRI-guided interstitial 192Ir-high-dose-rate brachytherapy of liver tumors

    Background and purpose: To evaluate the reconstruction accuracy of brachytherapy (BT) applicators tips in vitro and in vivo in MRI-guided 192Ir-high-dose-rate (HDR)-BT of inoperable liver tumors. Materials and methods: Reconstruction accuracy of plastic BT applicators, visualized by nitinol inserts, was assessed in MRI phantom measurements and in MRI 192Ir-HDR-BT treatment planning datasets of 45 patients employing CT co-registration and vector decomposition. Conspicuity, short-term dislocation, and reconstruction errors were assessed in the clinical data. The clinical effect of applicator reconstruction accuracy was determined in follow-up MRI data. Results: Applicator reconstruction accuracy was 1.6 ± 0.5 mm in the phantom measurements. In the clinical MRI datasets applicator conspicuity was rated good/optimal in ⩾72% of cases. 16/129 applicators showed not time dependent deviation in between MRI/CT acquisition (p > 0.1). Reconstruction accuracy was 5.5 ± 2.8 mm, and the average image co-registration error was 3.1 ± 0.9 mm. Vector decomposition revealed no preferred direction of reconstruction errors. In the follow-up data deviation of planned dose distribution and irradiation effect was 6.9 ± 3.3 mm matching the mean co-registration error (6.5 ± 2.5 mm; p > 0.1). Conclusion: Applicator reconstruction accuracy in vitro conforms to AAPM TG 56 standard. Nitinol-inserts are feasible for applicator visualization and yield good conspicuity in MRI treatment planning data. No preferred direction of reconstruction errors were found in vivo

  10. Stem signal suppression in fiber-coupled Al2O3:C dosimetry for 192Ir brachytherapy

    Kertzscher Schwencke, Gustavo Adolfo Vladimir; Andersen, Claus Erik; Edmund, J.M.;

    2011-01-01

    was adapted for on-line in-vivo dosimetry using fiber-coupled carbon doped aluminum oxide (Al2O3:C). The technique involved a two-channel optical filtration of the radioluminescence (RL) emitted from a pre-irradiated Al2O3:C crystal with enhanced sensitivity. The system responded linearly in the...... absorbed dose range 0.05–50 Gy, as needed under high dose rate (HDR) conditions. The dosimeter was irradiated in a water phantom using a 37 GBq 192Ir source at source-to-crystal distances ranging from 0.5 cm to 6.7 cm. For irradiation conditions that generated a stem component in the range 4%–15% in the...

  11. Determination of the G value for HDR 192Ir sources using ionometric measurements

    A dosimetry standard for the direct measurement of absolute dose to water for 192Ir source is currently still under development. For the time being, the dose to water conversion is done via a dose rate constant Λ and several correction factors accounting for scatter, attenuation, and anisotropy of the dose distribution among other effects. Recently a report has been published on a water-based calorimeter with an overall uncertainties of 1.9 % k=1. Chemical dosimetry using a standard FeS04 solution has shown to be a reliable absorbed dose standard. Absolute absorbed dose to water measurement has been explored using Fricke for 192Ir HDR sources with uncertainties estimated of 3.9 % k=1 and very recently similar work has reported improved results with much lower uncertainties of 1.24% k=1. The G values previously reported is the major uncertainty associated to this technique and this paper presents new G values measured with ion chambers using recent dosimetry protocols. For this study, the source was positioned in a PMMA holder with its center coinciding with the center of a Framer type the ion chamber and the Fricke solution holder. The solution container was constructed with the same volume and dimensions of the ion chamber. The measurements were taken with the ion chamber placed in one of the holders and the Fricke solutions in the other three holders. The chamber and the Fricke were irradiated in all four times around the source in order to minimize the positioning uncertainties and the average reading values for each one were taken. For the 60Co and 6 MV, the beam measurements were made with the chamber at the center and the solutions on each side

  12. Anisotropy measurement of {sup 192} Ir sources used in high dose rate brachytherapy; Medida da anisotropia de fontes de Ir-192 utilizadas em braquiterapia de altas taxa de dose

    Henn, Keli Cristina; Khoury, Helen J.; Luz, Lidia Cristina P. da [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

    1998-07-01

    This paper presents the dose distribution around the Ir-192 source used in MicroSelectron-HDR remote after loader system. The measurements were made in air with the source stationary, positioned at the position 1, from the indexer of the microSelectron-HDR. Measurements were made using TLD and for radial distances of 3.0, 5.0 and 7.0 cm, for values of the angle from 0 deg c to 360 deg C in steps of 15 deg C. (author)

  13. Dose specification for 192Ir high dose rate brachytherapy in terms of dose-to-water-in-medium and dose-to-medium-in-medium

    Dose calculation in high dose rate brachytherapy with 192Ir is usually based on the TG-43U1 protocol where all media are considered to be water. Several dose calculation algorithms have been developed that are capable of handling heterogeneities with two possibilities to report dose: dose-to-medium-in-medium (Dm,m) and dose-to-water-in-medium (Dw,m). The relation between Dm,m and Dw,m for 192Ir is the main goal of this study, in particular the dependence of Dw,m on the dose calculation approach using either large cavity theory (LCT) or small cavity theory (SCT). A head and neck case was selected due to the presence of media with a large range of atomic numbers relevant to tissues and mass densities such as air, soft tissues and bone interfaces. This case was simulated using a Monte Carlo (MC) code to score: Dm,m, Dw,m (LCT), mean photon energy and photon fluence. Dw,m (SCT) was derived from MC simulations using the ratio between the unrestricted collisional stopping power of the actual medium and water. Differences between Dm,m and Dw,m (SCT or LCT) can be negligible (<1%) for some tissues e.g. muscle and significant for other tissues with differences of up to 14% for bone. Using SCT or LCT approaches leads to differences between Dw,m (SCT) and Dw,m (LCT) up to 29% for bone and 36% for teeth. The mean photon energy distribution ranges from 222 keV up to 356 keV. However, results obtained using mean photon energies are not equivalent to the ones obtained using the full, local photon spectrum. This work concludes that it is essential that brachytherapy studies clearly report the dose quantity. It further shows that while differences between Dm,m and Dw,m (SCT) mainly depend on tissue type, differences between Dm,m and Dw,m (LCT) are, in addition, significantly dependent on the local photon energy fluence spectrum which varies with distance to implanted sources. (paper)

  14. Interstitial brachytherapy with 192-IR in treatment of recurrent malignant primary brain tumors. Braquiterapia intersticial con iridio-192 en el tratamiento de recidivas de tumores cerebrales tras cirugia y radioterapia

    Cardenes, R.; Martinez, R.; Victoria, C.; Nuez, L.; Clavo, B.; Sancedo, G. (Clinica Puerta de Hierro. Madrid (Spain))

    1994-01-01

    Seven patients with recurrent malignant primary brain tumors after surgery and radiation therapy were treated at the Clinica Puerta de Hierro (Madrid) by interstitial brachytherapy with 192-Ir sources. Implantations were performed using computerized tomography and dose prescription were determined following the Paris system rules for interstitial implants. The means dose deliberated was 50 to 65 Gy to the reference isodoses. At the last follow-up all patients except for one are alive and without evidence of progression of the disease. (Author) 35 refs.

  15. The correlation between DVH at CT-image based 192Ir intracavitary brachytherapy and effects or complications for patients with locally advanced cervical cancer

    Objective: To investigate the correlation between dose volume histogram (DVH) of tumor targets and organs at risk (OAR) at CT-image based 192Ir brachytherapy and effects and complications for patients with locally advanced cervical cancer. Methods: Ten patients with FIGO stage IIIB cervical cancer received CT image-based 192Ir intracavitary brachytherapy after 54 Gy of three-dimensional four-field pelvic external beam radiotherapy and concurrent weekly cisplatin chemotherapy. Before each brachytherapy, CT images were acquired with applicators in place. Gross tumor volume (GTV), clinical target volume (CTV) and OAR were contoured and inverse treatment planning was designed and optimized by using PLATO treatment planning system. Conventional two-dimensional plans were also designed for comparison.The total intracavitary brachytherapy dose was 30-42 Gy in 5-7 fractions. The patients were followed, and the local control and complications were analyzed. The biologically equivalent dose (BED) and biologically equivalent dose in 2 Gy fractions (BED2) for GTV, CTV and OAR were calculated. The minimum dose in the most irradiated tissue volume 2 cm3 (D2cm3)adjacent to the applicator of the sigmoid colon, rectum,bladder and small bowel was determined from the DVH. Results: The 1-year local pelvic control rate was 90% and grade 1-2 late complication of sigmoid colon and rectum was 50%. No grade 3 or more complications developed. On CT-image based planning, the BED and BED2 to 90% of the CTV (D90) were 95.50 Gy ± 7. 81 Gy and 79. 73 Gy ± 6. 57 Gy. The BED and BED2 to 90% of the GTV (D90) were 101.86 Gy ± 7.27 Gy and 84. 95 Gy ± 6. 1 Gy. The volume enclosed by 90% of prescribed dose (V90) for GTV and CTV were 92% ±4% and 87% ±7% respectively. The D2cm3 for rectum and sigmoid colon were 74. 97 Gy ±1.64 Gy and 67. 93 Gy ± 4. 30 Gy(EQD2, α/β = 3). Comparing with 2D brachytherapy plans , CT - image based planning has improved D90 and V90 for GTV and CTV with similar dose

  16. Calibration of 192Ir high-dose-rate afterloading systems

    A method is described for calibration of 192Ir high-dose-rate (HDR) brachytherapy afterloading systems. Since NIST does not offer calibration of ionization chambers with the gamma-ray spectrum of iridium-192, an interpolation procedure is employed, using calibrations above (137Cs, 662 keV) and below (250 kVcp, 146-keV x rays) the exposure-weighted average 192Ir energy of 397 keV. The same total wall + cap thickness must be used for both calibrations, and for the 192Ir measurements. A wall + cap thickness of 0.3 g/cm2 is recommended to assure charged particle equilibrium and to exclude secondary electrons emitted from the source encapsulation. Procedures are described for determining the corrections for source-chamber distance and room scatter during the source calibration in inverse-square-law geometry. A new well-type ionization chamber has been designed specifically for convenient routine use with the HDR afterloading system. It can be calibrated by means of a previously calibrated 192Ir source, and offers a simple means for verifying the decay rate and for calibrating 192Ir replacement sources

  17. Intercomparison of calibration procedures of high dose rate 192 Ir sources in Brazil and a proposal of a new methodology

    The objective of this paper is to report the results of an intercomparison of the calibration procedures for 192 Ir sources presently in use in Brazil and to proposal a calibration procedure to derive the Nk for a Farmer type ionization chamber for 192 Ir energy by interpolating from a 60 Co gamma-rays and 250 kV x-rays calibration factors. the intercomparison results were all within ± 3.0 % except one case where 4.6 % was observed and latter identified as a problem with N-k value for X-rays. The method proposed by the present work make possible the improvement of the metrological coherence among the calibration laboratories and their users once the Nk values could then provided by any of the members of SSDL network. (Author)

  18. Differentiation between radionecrosis and malignant brain tumor recurrence in patients treated by 192Ir HDR brachytherapy: 1H - MRS analysis of the brain metabolic spectrum

    Computerized tomography (CT) with contrast infusion and Magnetic Resonance Imaging (MRI) do not differentiate radionecrosis and malignant tumor recurrence. Proton Magnetic Resonance Spectroscopy seems to be a new radiological method that could solve this problem. The aim of the study was to evaluate the usability of 1H - MRS in patients after brachytherapy. Sixty patients were treated by 192Ir HDR brachytherapy because of malignant brain tumors (gliomas and brain metastases). Prospectively, 4 months after brachytherapy, 24 patients underwent MRI and 1H - MRS examinations. All patients qualified for the prospective study were in good general condition before and after the brachytherapy (Karnofsky Performance Score (KPS) > 60%). Combined assessment of MRI and 1H - MRS gave us the possibility to differentiate the observed pathological changes. In 18 cases (75%) there was a decrease in tumor volume. The tumor infiltration area was larger than the necrotic area in 5 cases. An isolated recurrence mass was observed in only one case. Neurosurgical brain decompression with pathological mass resection was needed in 6 patients with increased intracranial pressure and enhanced neurological deficits. Histopathological examination confirmed the diagnosis revealed in the 1H - MRS examination in each case. Proton Magnetic Resonance Spectroscopy is helpful in evaluating the influence of radiation on the tumor and the surrounding brain tissue. Moreover, it solves the problem of differentiating between radionecrosis and tumor recurrence. (author)

  19. Proposal of a postal system for Ir-192 sources calibration used in high dose rate brachytherapy with LiF:Mn:Ti thermoluminescent dosemeters; Proposta de um sistema postal para a calibracao de fontes de {sup 192} Ir, utilizadas em braquiterapia de alta taxa de dose, com dosimetros termoluminescentes de LiF: Mn: Ti

    Vieira, W.S.; Borges, J.C.; Almeida, C.E.V. [Instituto de Radioprotecao e Dosimetria. CNEN Caixa Postal 37750, 22780-160, Rio de Janeiro (Brazil)

    1998-12-31

    A proposal in order to improve the brachytherapy quality control and to allow postal intercomparison of Ir-192 sources used in high dose rate brachytherapy has been presented. The LiF: Mn: Ti (TLD 100) detector has been selected for such purpose. The experimental array and the TLDs irradiation and calibration techniques, at the treatment units, have been specified in the light of more recent methodology of Ir-192 calibration sources. (Author)

  20. In vivo assessment of catheter positioning accuracy and prolonged irradiation time on liver tolerance dose after single-fraction 192Ir high-dose-rate brachytherapy

    To assess brachytherapy catheter positioning accuracy and to evaluate the effects of prolonged irradiation time on the tolerance dose of normal liver parenchyma following single-fraction irradiation with 192 Ir. Fifty patients with 76 malignant liver tumors treated by computed tomography (CT)-guided high-dose-rate brachytherapy (HDR-BT) were included in the study. The prescribed radiation dose was delivered by 1 - 11 catheters with exposure times in the range of 844 - 4432 seconds. Magnetic resonance imaging (MRI) datasets for assessing irradiation effects on normal liver tissue, edema, and hepatocyte dysfunction, obtained 6 and 12 weeks after HDR-BT, were merged with 3D dosimetry data. The isodose of the treatment plan covering the same volume as the irradiation effect was taken as a surrogate for the liver tissue tolerance dose. Catheter positioning accuracy was assessed by calculating the shift between the 3D center coordinates of the irradiation effect volume and the tolerance dose volume for 38 irradiation effects in 30 patients induced by catheters implanted in nearly parallel arrangement. Effects of prolonged irradiation were assessed in areas where the irradiation effect volume and tolerance dose volume did not overlap (mismatch areas) by using a catheter contribution index. This index was calculated for 48 irradiation effects induced by at least two catheters in 44 patients. Positioning accuracy of the brachytherapy catheters was 5-6 mm. The orthogonal and axial shifts between the center coordinates of the irradiation effect volume and the tolerance dose volume in relation to the direction vector of catheter implantation were highly correlated and in first approximation identically in the T1-w and T2-w MRI sequences (p = 0.003 and p < 0.001, respectively), as were the shifts between 6 and 12 weeks examinations (p = 0.001 and p = 0.004, respectively). There was a significant shift of the irradiation effect towards the catheter entry site compared with the

  1. Fractionated intraluminal HDR {sup 192}Ir brachytherapy as palliative treatment in patients with endobronchial metastases from non-bronchogenic primaries

    Stranzl, H.; Gabor, S.; Mayer, R.; Prettenhofer, U.; Wurzinger, G.; Hackl, A. [University Medical School of Graz (Austria)

    2002-08-01

    Aim: To evaluate the efficacy of iridium-192 high-dose rate (HDR) endobronchial brachytherapy for the palliation of symptoms caused by endobronchial metastases of non-bronchogenic primaries. Patients and method: Between 1991 and 1998, eleven patients (female n=3, male n=8; age: median 66 years, range 44-81 years) underwent intraluminal HDR brachytherapy for histologically confirmed endobronchial metastases from non-pulmonary primary tumors of various sites like urogenital tract (n=5), gastrointestinal tract (n=3), ear/nose/throat (n=2) and breast (n=1). The median time between diagnosis of the primary non-bronchogenic tumor and histopathological diagnosis of the endobronchial metastases was 39 months, range 1-99 months. A total dose of 15-20 Gy was delivered in three to four fractions of 5-6 Gy once a week. No palliative chemotherapy was added. Results: Median follow-up after palliative brachytherapy was 15 months (range 1.4-59 months). Objectively, complete endoscopic response was observed in three (27%) patients, and in five (46%) others partial opening of the initially obstructed airway was achieved. Treatment was judged unsuccessful in three (27%) patients. No patient showed up with local progression. At date of analysis five patients were alive with documented residual tumor (80%) or complete response (20%). Relief of symptoms occurred in the vast majority of patients (n=8, 73%). Conclusion: HDR intraluminal brachytherapy palliates symptoms in patients suffering from endobronchial metastases of nonpulmonary primary tumors. The applied treatment is a safe, effective and well tolerated palliative procedure leading to an improved patient quality of life. (orig.) [German] Hintergrund: Untersuchung des palliativen Effektes einer fraktionierten intraluminalen Iridium-192-High-Dose-Rate-(HDR-)Brachytherapie bei Patienten mit endobronchialen Metastasen eines primaer nicht bronchogenen Tumors. Patienten und Methode: Zwischen April 1991 und September 1998 wurden elf

  2. Standardization of 192Ir

    Two 192Ir solutions were standardized by NPL and CBNM within the framework of EUROMET project no. 219. The 4 πβ-γ-coincidence method was used for these measurements, a 4πCsI(Tl) detector for gamma-ray spectrometry, and a NaI(Tl) well counter for 4π-gamma integral counting. The uncertainty of the result was 0.3%, corresponding to one standard deviation. Traceability was established to BIPM for the 192Ir activity measurements. (orig.)

  3. Comparison of two different methods to determine the air kerma calibration factor (NK) for 192Ir

    In brachytherapy, encapsulated radioactive Low Dose Rate (LDR) and High Dose Rate (HDR) sources are used to deliver a dose to tissue near the source. One of the nuclides used in LDR as well as in HDR brachytherapy sources is 192Ir. In document IAEA-TECDOC-1079, Calibration of Brachytherapy Sources, recommendations on standardized procedures for the calibration of brachytherapy sources at SSDLs and hospitals are given. One of these recommendations is the use of an ionisation chamber with an air-kerma calibration factor for 192lr sources. The problem to derive a calibration factor for 192Ir is that the most important part of the spectrum of an 192lr brachytherapy source falls in an energy gap between the standards for x-rays and the standards for gamma-rays established at primary laboratories. It is therefore unavoidable to obtain the air kerma calibration for the ionisation chamber using an indirect method. The method recommended by IAEA for the determination of the air-kerma calibration factors is based on a technique developed by Goetsch et al. In the Netherlands a different method is recommended. This method is based on a weighting procedure of the 192Ir energy spectrum over the response curve of an ionisation chamber and differs with the procedure recommended by IAEA for a NE2561 ionisation chamber by about 0.9 %

  4. High dose rate 192Ir calibration: Indonesia experiences

    Indonesia with a population of more than 200 Million people which spread on about 5000 islands, up to now only has 23 radiotherapy centers and some not active anymore. As mention by Parkin et al that Cervix/Utery and breast cancer are the most estimated numbers of new cases of cancers in women for developing countries, stomach and lung cancers in men. Indonesia as a developing country is likely similar to other developing countries on numbers of new cases of cancers in women. But quite different in men, in Indonesia the most common cancers are nasopharynx and thyroid cancers. The use of lr-192 sources in high dose-rate (HDR) remotely afterloaded brachytherapy treatments have greatly increased in recent years and variety of such sources are commercially available. Nine radiotherapy centers in Indonesia installed Nucletron microSelectron HDR remote afterloader. Based on the data of CiptoMangunkusurno Hospital, Jakarta that the most common cancers are the cervix, breast, nasopharynx and thyroid cancers which of percentage are about 31%, 25 %, 13%, and 6 % respectively. It means that the use of HDR 192Ir brachytherapy has to be an effective tool in the treatments. Two methods have been studied and applied to calibrate HDR 192Ir brachytherapy in Indonesia, especially for Nucletron microSelectron HDR 192lr remote afterloader brachytherapy. Calibration of HDR 192Ir brachytherapy source has been done by Cavity lonization Chamber and with Well Type lonization Chamber. First, 0.6 cc of NE Farmer type dosimeter that was calibrated to 60Co and 250 kV of x-rays in air kerma was used in this experiment. Position of measurement (detector and source) at the center of the room and about 1 meter from the floor. Eight variation of distances from 10 cm to 40 cms have been carried out measurement as recommended by IAEA-TECDOC-1079. Correction have been given for scatters, non-uniformity, and attenuation. To solve the problem of scatter correction factor was used Matlab programming. A

  5. Cuban laboratory proficiency test for calibration of well-type chambers using two types of HDR 192Ir sources

    The proficiency test by inter-laboratory comparisons is the commonly accepted procedure both for validation of the testing methods and assuring the quality of the calibration undertaken by the competence laboratories. The Secondary Standard Dosimetry Laboratory (SSDL) of Cuba is located at the Centro de Proteccion e Higiene de las Radiaciones (CPHR). The SSDL has recently implemented the calibration methodology of well-type chambers using the High Dose Rate 192Ir sources under activities of the technical co-operation project with the International Atomic Energy Agency. The reference standard of CPHR is traceable to the primary standard of the German National Metrology Institute (Physikalisch-Technische Bundesanstalt - PTB). The method used by the secondary laboratory follows the Technical Document 1274. On this method the source available is measured in a well-type chamber calibrated against the primary standard. Because there is no HDR afterloader at the SSDL, the calibration of the client source can be done only in the hospital set-up. The user's chamber is calibrated by means of a calibrated source. This method has the advantage that the measurement set-up is simplified but problems can arise from the use of different source designs during calibration of the secondary standard at the primary laboratory and calibration of the user's chambers at the hospital set-up. The variation of the calibration coefficient of the PTW 33004 chamber due to the use of different sources and adapters has already been measured experimentally. The larger differences can be found near 4%. All those facts reinforced the idea to conduct a proficiency test to demonstrate that the calibration procedure used by SSDL can be applied in practice and will not lead to the incorrect calibration coefficient within the stated uncertainty

  6. 192Ir high dose rate (HDR) interstitial brain implant: optimisation

    The new modality of stepping source dosimetry system (SSDs) illustrates a remarkable improvement in attaining the uniform and homogeneous dose distribution within the target volume. The technique enables the physicist to correct for a certain amount of misplacement or curvature of implant geometry. The short course of brachytherapy provides good palliation in terms of functional improvements with low and acceptable toxicity in high-grade glioma. With continual refinements of the technique, brachytherapy performed by a skilled brachytherapy team offers an opportunity to improve patient survival and quality of life. Since 1997, micro selectron HDR 192Ir treatments are done including gynecological, oesophageal, breast, surface mould, soft tissue sarcoma (STS) and brain in our hospital. In this paper, procedure of interstitial brain implant in glioma as implant technique, simulation and treatment planning will be discussed

  7. SU-E-T-580: On the Significance of Model Based Dosimetry for Breast and Head and Neck 192Ir HDR Brachytherapy

    Peppa, V; Pappas, E; Pantelis, E; Papagiannis, P [Medical Physics Laboratory, Medical School, University of Athens, Athens (Greece); Major, T; Polgar, C [National Institute of Oncology, Budapest (Hungary)

    2015-06-15

    Purpose: To assess the dosimetric and radiobiological differences between TG43-based and model-based dosimetry in the treatment planning of {sup 192}Ir HDR brachytherapy for breast and head and neck cancer. Methods: Two cohorts of 57 Accelerated Partial Breast Irradiation (APBI) and 22 head and neck (H&N) patients with oral cavity carcinoma were studied. Dosimetry for the treatment plans was performed using the TG43 algorithm of the Oncentra Brachy v4.4 treatment planning system (TPS). Corresponding Monte Carlo (MC) simulations were performed using MCNP6 with input files automatically prepared by the BrachyGuide software tool from DICOM RT plan data. TG43 and MC data were compared in terms of % dose differences, Dose Volume Histograms (DVHs) and related indices of clinical interest for the Planning Target Volume (PTV) and the Organs-At-Risk (OARs). A radiobiological analysis was also performed using the Equivalent Uniform Dose (EUD), mean survival fraction (S) and Tumor Control Probability (TCP) for the PTV, and the Normal Tissue Control Probability (N TCP) and the generalized EUD (gEUD) for the OARs. Significance testing of the observed differences performed using the Wilcoxon paired sample test. Results: Differences between TG43 and MC DVH indices, associated with the increased corresponding local % dose differences observed, were statistically significant. This is mainly attributed to their consistency however, since TG43 agrees closely with MC for the majority of DVH and radiobiological parameters in both patient cohorts. Differences varied considerably among patients only for the ipsilateral lung and ribs in the APBI cohort, with a strong correlation to target location. Conclusion: While the consistency and magnitude of differences in the majority of clinically relevant DVH indices imply that no change is needed in the treatment planning practice, individualized dosimetry improves accuracy and addresses instances of inter-patient variability observed. Research

  8. An innovative method for 192Ir HDR calibration by farmer chamber, V-film, and solid phantom

    A simple, practical and economical technique was proposed to calibrate an 192Ir HDR brachytherapy source in terms of air kerma strength. This technique makes use of the 0.6 cm3 Farmer type ion chamber, radiographic film and polystyrene phantom. These tools are commonly used for dosimetry quality assurance of the clinical linear accelerator. In this study, the Exradin A19, PTW N30004 and TM30001 Farmer type ion chambers were used for the calibration of the 192Ir HDR source. To perform the calibration, a 25.4x30.5 cm2 radiographic film was taped on a piece of polystyrene plate, and a straight applicator probe of a HDR brachytherapy unit and the Farmer type ion chamber were affixed to the film envelope. The film was irradiated by the 192Ir source, followed by an exposure in the simulator X-ray beam. The film set with the film removed was then placed on a 5 cm thick polystyrene phantom for calibration measurement. Based on the electrometer reading from the Farmer type ion chamber irradiated by 192Ir and the measured source-to-chamber distance by means of the images on the developed film, we can calculate the air kerma strength of the 192Ir using the new technique. Our calibration results were compared to the data provided by the manufacturer and that of five different well type ion chambers, namely, Sun Nuclear cooperation (SNC) 1008, Nucletron SDS 077.091, SDS 077.094, PTW TN33004 and Standard Imaging (SI) HDR-1000 Plus. The differences were all within 1.6%. Relative to the '7-distance measurement technique' by Stump et al., 2002, our method is more efficient if our empirical formula was used. In summary, our method is simpler and cost-effective to calibrate an 192Ir HDR brachytherapy source for those hospitals without a calibration jig or a well type ion chamber.

  9. Comparison of 60Cobalt and 192Iridium sources in high dose rate afterloading brachytherapy

    Purpose: 60Co sources with dimensions identical to those of 192Ir have recently been made available in clinical brachytherapy. A longer half time reduces demands on logistics and quality assurance and perhaps costs. Material and Methods: Comparison of the physical properties of 60Co and 192Ir with regard to brachytherapy. Results: Required activities for the same air kerma rate are lower by a factor of 2.8 for 60Co. Differential absorption in tissues of different densities can be neglected. Monte Carlo calculations demonstrate that integral dose due to radial dose fall off is higher for 192Ir in comparison to 60Co within the first 22 cm from the source (normalization at 1 cm). At larger distances this relationship is reversed. Conclusion: Clinical examples for intracavitary and interstitial applications however, show practically identical dose distributions in the treatment volume. (orig.)

  10. Intercomparison of calibration procedures of high dose rate {sup 192} Ir sources in Brazil and a proposal of a new methodology; Intercomparacao de procedimientos de calibracao de fontes de {sup 192} Ir de alta taxa de dose no Brasil e proposta de uma nova metodologia

    Marechal, M.H.; Almeida, C.E. de [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes IRD/CNEN. Caixa Postal 37750 CEP 22780-160 Rio de Janeiro (Brazil)

    1998-12-31

    The objective of this paper is to report the results of an intercomparison of the calibration procedures for {sup 192} Ir sources presently in use in Brazil and to proposal a calibration procedure to derive the N{sub k} for a Farmer type ionization chamber for {sup 192} Ir energy by interpolating from a {sup 60} Co gamma-rays and 250 kV x-rays calibration factors. the intercomparison results were all within {+-} 3.0 % except one case where 4.6 % was observed and latter identified as a problem with N-k value for X-rays. The method proposed by the present work make possible the improvement of the metrological coherence among the calibration laboratories and their users once the N{sub k} values could then provided by any of the members of SSDL network. (Author)

  11. Traceable calibration of a reference well chamber at HDR 192Ir energy

    With the increasing use of the remote afterloading HDR 192Ir equipment in the country, an urgent need was felt to establish a Standard for the HDR 192Ir source. The objective of the programme was to offer traceable calibration to all the hospital well chambers, at HDR 192Ir energy

  12. Response of an implantable MOSFET dosimeter to 192Ir HDR radiation.

    Fagerstrom, Jessica M; Micka, John A; DeWerd, Larry A

    2008-12-01

    New in vivo dosimetry methods would be useful for clinical HDR brachytherapy. An implantable MOSFET Dose Verification System designed by Sicel Technologies, Inc. was examined for use with 192Ir HDR applications. This investigation demonstrated that varying the dose rate from 22 to 84 cGy/min did not change detector response. The detectors exhibited a higher sensitivity to 192Ir energies than 60Co energies. A nonlinear accumulated dose effect was characterized by three third-order polynomials fit to data from detectors placed at three different distances from the source. The detectors were found to have minimal rotational angular dependence. A strong longitudinal angular dependence was found when the detector's copper coil and electronics assembly were aligned between the MOSFETs and incident radiation. This orientation showed a 16% decrease in response relative to other orientations tested. PMID:19175130

  13. Response of an implantable MOSFET dosimeter to {sup 192}Ir HDR radiation

    Fagerstrom, Jessica M.; Micka, John A.; DeWerd, Larry A. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2008-12-15

    New in vivo dosimetry methods would be useful for clinical HDR brachytherapy. An implantable MOSFET Dose Verification System designed by Sicel Technologies, Inc. was examined for use with {sup 192}Ir HDR applications. This investigation demonstrated that varying the dose rate from 22 to 84 cGy/min did not change detector response. The detectors exhibited a higher sensitivity to {sup 192}Ir energies than {sup 60}Co energies. A nonlinear accumulated dose effect was characterized by three third-order polynomials fit to data from detectors placed at three different distances from the source. The detectors were found to have minimal rotational angular dependence. A strong longitudinal angular dependence was found when the detector's copper coil and electronics assembly were aligned between the MOSFETs and incident radiation. This orientation showed a 16% decrease in response relative to other orientations tested.

  14. Standardization of sup 192 Ir

    Reher, D.F.G.; Roost, E. de; Sibbens, G.; Denecke, B.; Altzitzoglou, T.; Ballaux, C. (CEC-JRC Central Bureau for Nuclear Measurements, Geel (Belgium)); Woods, M.J. (National Physical Lab., Teddington (United Kingdom)); Funck, E. (Physikalisch-Technische Bundesanstalt, Braunschweig (Germany))

    1992-02-01

    Two {sup 192}Ir solutions were standardized by NPL and CBNM within the framework of EUROMET project no. 219. The 4 {pi}{beta}-{gamma}-coincidence method was used for these measurements, a 4{pi}CsI(Tl) detector for gamma-ray spectrometry, and a NaI(Tl) well counter for 4{pi}-gamma integral counting. The uncertainty of the result was 0.3%, corresponding to one standard deviation. Traceability was established to BIPM for the {sup 192}Ir activity measurements. (orig.).

  15. Dosimetric characterization and output verification for conical brachytherapy surface applicators. Part I. Electronic brachytherapy source

    Purpose: Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR)192Ir sources, as well as electronic brachytherapy sources. Part I of this paper will discuss the applicators used with electronic brachytherapy sources; Part II will discuss those used with HDR 192Ir sources. Although the use of these applicators has gained in popularity, the dosimetric characteristics including depth dose and surface dose distributions have not been independently verified. Additionally, there is no recognized method of output verification for quality assurance procedures with applicators like these. Existing dosimetry protocols available from the AAPM bookend the cross-over characteristics of a traditional brachytherapy source (as described by Task Group 43) being implemented as a low-energy superficial x-ray beam (as described by Task Group 61) as observed with the surface applicators of interest. Methods: This work aims to create a cohesive method of output verification that can be used to determine the dose at the treatment surface as part of a quality assurance/commissioning process for surface applicators used with HDR electronic brachytherapy sources (Part I) and192Ir sources (Part II). Air-kerma rate measurements for the electronic brachytherapy sources were completed with an Attix Free-Air Chamber, as well as several models of small-volume ionization chambers to obtain an air-kerma rate at the treatment surface for each applicator. Correction factors were calculated using MCNP5 and EGSnrc Monte Carlo codes in order to determine an applicator-specific absorbed dose to water at the treatment surface from the measured air-kerma rate. Additionally, relative dose

  16. An innovative method for {sup 192}Ir HDR calibration by farmer chamber, V-film, and solid phantom

    Chang, Liyun; Ding, Hueisch-Jy [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Ho, Sheng-Yow, E-mail: shengho@seed.net.tw [Department of Radiation Oncology, Sinlau Christian Hospital, Tainan, Taiwan (China)

    2011-08-01

    A simple, practical and economical technique was proposed to calibrate an {sup 192}Ir HDR brachytherapy source in terms of air kerma strength. This technique makes use of the 0.6 cm{sup 3} Farmer type ion chamber, radiographic film and polystyrene phantom. These tools are commonly used for dosimetry quality assurance of the clinical linear accelerator. In this study, the Exradin A19, PTW N30004 and TM30001 Farmer type ion chambers were used for the calibration of the {sup 192}Ir HDR source. To perform the calibration, a 25.4x30.5 cm{sup 2} radiographic film was taped on a piece of polystyrene plate, and a straight applicator probe of a HDR brachytherapy unit and the Farmer type ion chamber were affixed to the film envelope. The film was irradiated by the {sup 192}Ir source, followed by an exposure in the simulator X-ray beam. The film set with the film removed was then placed on a 5 cm thick polystyrene phantom for calibration measurement. Based on the electrometer reading from the Farmer type ion chamber irradiated by {sup 192}Ir and the measured source-to-chamber distance by means of the images on the developed film, we can calculate the air kerma strength of the {sup 192}Ir using the new technique. Our calibration results were compared to the data provided by the manufacturer and that of five different well type ion chambers, namely, Sun Nuclear cooperation (SNC) 1008, Nucletron SDS 077.091, SDS 077.094, PTW TN33004 and Standard Imaging (SI) HDR-1000 Plus. The differences were all within 1.6%. Relative to the '7-distance measurement technique' by Stump et al., 2002, our method is more efficient if our empirical formula was used. In summary, our method is simpler and cost-effective to calibrate an {sup 192}Ir HDR brachytherapy source for those hospitals without a calibration jig or a well type ion chamber.

  17. Dosimetric accuracy of a deterministic radiation transport based 192Ir brachytherapy treatment planning system. Part III. Comparison to Monte Carlo simulation in voxelized anatomical computational models

    Purpose: To compare TG43-based and Acuros deterministic radiation transport-based calculations of the BrachyVision treatment planning system (TPS) with corresponding Monte Carlo (MC) simulation results in heterogeneous patient geometries, in order to validate Acuros and quantify the accuracy improvement it marks relative to TG43. Methods: Dosimetric comparisons in the form of isodose lines, percentage dose difference maps, and dose volume histogram results were performed for two voxelized mathematical models resembling an esophageal and a breast brachytherapy patient, as well as an actual breast brachytherapy patient model. The mathematical models were converted to digital imaging and communications in medicine (DICOM) image series for input to the TPS. The MCNP5 v.1.40 general-purpose simulation code input files for each model were prepared using information derived from the corresponding DICOM RT exports from the TPS. Results: Comparisons of MC and TG43 results in all models showed significant differences, as reported previously in the literature and expected from the inability of the TG43 based algorithm to account for heterogeneities and model specific scatter conditions. A close agreement was observed between MC and Acuros results in all models except for a limited number of points that lay in the penumbra of perfectly shaped structures in the esophageal model, or at distances very close to the catheters in all models. Conclusions: Acuros marks a significant dosimetry improvement relative to TG43. The assessment of the clinical significance of this accuracy improvement requires further work. Mathematical patient equivalent models and models prepared from actual patient CT series are useful complementary tools in the methodology outlined in this series of works for the benchmarking of any advanced dose calculation algorithm beyond TG43.

  18. The production of Iridium-192 (192-Ir) sealed source by Nuclear Malaysia for non-destruction testing (NDT)

    Malaysian Nuclear Agency (Nuclear Malaysia) has been engaged in the production of a few radioisotopes that can be used in agriculture, medicine, industries and further more to be used in other applications, such as teaching, training and calibration. These radioisotopes are produced by using our TRIGA MARK II research reactor which provides a maximum neutron flux at the central thimble irradiation position about 10E12 ncm-2s-1. The achievable quantity of radioactivity of radioisotope produced by this reactor is relatively low for most of the applications due to limitation of neutron flux available. This limitation is seen to exist for quiet some time until a higher neutron flux is available in the future. In addition to this, our reactor is approaching toward the end of their operational performance. In order to sustain Nuclear Malaysia active involvement in radioisotope production and considering the current production facilities available, other possible mode of radioisotope production are developed. In line with this, a joint venture project between Nuclear Malaysia and a NDT company in Malaysia has been established to produce the Ir-192 Sealed Source. The project consists of technology transfer from Korean Atomic Energy Agency Research Institute (KAERI) /Ho Jin Industry Ltd. to Nuclear Malaysia. Series of production equipment are installed in our 10 cm thickness lead (Pb) shielded box known as hot-cell. The irradiated double encapsulated Ir-192 disc imported from KAERI will undergo final assembly. Decay sources from Gamma Projector is removed, cut and stored in a waste container. Steps of production include source changing, cutting, cramping, dimension test and Go/No Go testing. The Atomic Energy Licensing Board (AELB) has issued the above production facility for manufacturing of Ir-192 pigtail for Gamma Projector types Tech-ops. (Author)

  19. Fast 3D 192Ir-afterloading quality assurance a new general dosimetric concept applying tissue substituting scintillators

    Problems of brachytherapy: The steep dose gradient demands high precision in dosimetry, localization, planning and quality assurance. 192Ir-Dosimetry: The broad, depth dependent, low energy photon spectrum, requires dosemeter probes with a wide linear range and high spatial resolution, being independent of energy, incidence and temperature, to overcome the disadvantages of common detectors. Tissue substituting plastic scintillators are optimal for brachytherapy dosimetry. Tiny (1-10 mm3) NE 102A detectors, connected by thin multi-fibre plastic light guides (Cerenkov compensated) to photo-multiplier tubes (PMTs) of high sensitivity and stability allow fast measurements of all basic absorbed dose data within ≤2% precision up to 10 cm depth with high spatial resolution. Afterloading quality assurance: Multi-detector arrays and multi-channel PMTs, open new possibilities of fast 3D-quality assurance by simultaneous measurement at many points. In tissue equivalent phantoms this allows fast systematic checks of stepping source hard-and software, as well as individual dosimetric treatment planning, optimization, simulation, and verification. Afterloading dose monitor: Integrated into the applicator, the really delivered distribution of absorbed dose to water is monitored directly during stepping source afterloading brachytherapy with high spatial (≤0.1 mm) or temporal resolution (≤0.1 s). It indicates errors of planning or application, of step position or step size, of dwell time or travel time. In combination with on-line 3D treatment planning the distribution of dose really delivered can be visualized. Verification: The tiny plastic scintillator array is the ideal probe for192 Ir-afterloading in-vivo dosimetry, also in IORT. Conclusion: Plastic scintillation dosimetry enables versatile and fast 3D-quality assurance of 192Ir-afterloading with high precision

  20. The theoretical basis and clinical methodology for stereotactic interstitial brain tumor irradiation using iododeoxyuridine as a radiation sensitizer and samarium-145 as a brachytherapy source

    High grade astrocytomas have proven resistant to all conventional therapy. A technique to produce radiation enhancement during interstitial brain tumor irradiation by using a radiation sensitizer (IdUrd) and by stimulation of Auger electron cascades through absorption of low energy photons in iodine (Photon activation) is described. Clinical studies using IdUrd, 192Ir as a brachytherapy source, and external radiation have produced promising results. Substituting samarium-145 for 192Ir in this protocol is expected to produce enhanced results. 15 refs

  1. The air-kerma rate constant of 192Ir.

    Ninković, M M; Raiĉevìć, J J

    1993-01-01

    The air-kerma rate constant gamma delta (and its precursors), as one of the basic radiation characteristics of 192Ir, was determined by many authors. Analysis of accessible data on this quantity led us to the conclusion that published data strongly disagree. That is the reason we calculated this quantity on the basis of our and many other authors' gamma-ray spectral data and the latest data for mass energy-transfer coefficients for air. In this way, a value was obtained for gamma delta of 30.0 +/- 0.9 a Gy m2 s-1 Bq-1 for an unshielded 192Ir source and 27.8 +/- 0.9 a Gy m2s -1Bq-1 for a standard packaged radioactive source taking into account attenuation of gamma rays in the platinum source wall. PMID:8416220

  2. A comparison of dosimetric parameters and dose distribution around CF -252 and IR-192 LDR Brachytherapy Sources

    Full text: The purpose of this work is the evaluation and comparison of the dose rate distributions around a 252Cf Applicator Tube (AT) and 192Ir LDR sources. The dosimetric parameters were determined for both sources according to the updated AAPM TG-43U1 protocol. The calculations were performed using the Monte Carlo N-particle MCNP code, version 5C. To validate the results of this study, they were compared to experimental and analytical dosimetric data available in the literature for similar source configurations. After validation, the Monte Carlo computer code was applied to investigate the difference between dose rate distributions around the two brachytherapy sources, with the purpose of comparing their efficiency in treatment. The data so obtained also provide further information about spatial dose distributions and are important for detailed treatment planning with 252 Cf or 192Ir LDR sources for interstitial and intracavitary therapy

  3. Broad-beam transmission data for new brachytherapy sources, Tm-170 and Yb-169

    The characteristics of the radionuclides 170Tm and 169Yb are highly interesting for their use as high dose-rate brachytherapy sources. The introduction of brachytherapy equipment containing these sources will lead to smaller required thicknesses of the materials used in radiation protection barriers compared with the use of conventional sources such as 192Ir and 137Cs. The purpose of this study is to determine the required thicknesses of protection material for the design of the protecting walls. Using the Monte Carlo method, transmission data were derived for broad-beam geometries through lead and concrete barriers, from which the first half value layer and tenth value layer are obtained. In addition, the dose reduction in a simulated patient was studied to determine whether transmission in the patient is a relevant factor in radiation protection calculations. (authors)

  4. Application of the Cavity theory in the calibration of the powder TLD-100 for energies of 60 Co, 137 Cs, 192 Ir and RX 50, 250 k Vp

    A powder lot TLD-100 (LiF:Mg,Ti) in absorbed dose terms in water Dw for the following radiation sources: 60 Co, 137 Cs and RX 50 and 250 k Vp is calibrated; to continuation is made a lineal interpolation of the TLD response in function of the effective energy of the sources to calibrate a source of 192 Ir. The calibration of those fields in Dw are carried out with aid of the Bragg-Gray cavity theory, the one which finds implicit in the following protocols: IAEA-TRS 398 for the 60 Co and the AAPM TG61 for X Rays of 50 and 250 k Vp. Additionally the AAPM protocol TG43 to determine the Dw in function of the kerma intensity Sk in the case of the 137 Cs is used. The calibration curves for the response of the TLD-100 RTLD vs Dw, corresponding to each one of the sources already mentioned are constructed. The RTLD vs Dw by least heavy square by means of a second order polynomial that corrects the supralineality of the response is adjusted. The curves are validated by lack of LOF adjustment and by the Anderson Darling normality test. Later the factors of sensitivity (Fs) for the sources of 192 Ir: Micro Selectron and Vari Source are interpolated, used respectively in the A and B hospitals for treatments of brachytherapy of high dose rate (HDR), the expanded uncertainties associated to the Dw and Fs are also determined. Finally, an acrylic phantom and a couple of capsules are already sent to the hospitals mentioned, to verify a nominal Dw of 2 Gy, in a case an underestimate in 5.5% in the imparted Dw and in other an overestimation in a range of -1.5 to -8.0% was obtained. The obtained results in this work establish the bases for the development of a national dosimetric quality control program for brachytherapy of HDR with sources of 192 Ir. (Author)

  5. Determination of exit skin dose for 192Ir intracavitary accelerated partial breast irradiation with thermoluminescent dosimeters

    Raffi, Julie A.; Stephen D. Davis; Hammer, Cliff G.; Micka, John A.; Kunugi, Keith A.; Musgrove, Jana E.; Winston, John W.; Ricci-Ott, Terresa J.; DeWerd, Larry A.

    2010-01-01

    Purpose: Intracavitary accelerated partial breast irradiation (APBI) has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the skin is a major concern and can be a limiting factor for these treatments. Most treatment planning systems (TPSs) currently used for high dose-rate (HDR) 192Ir brachytherapy overe...

  6. Evaluation and test of 192Ir air kerma strength for afterloading systems

    Objective: To study the method of measuring air kerma strength of afterloading units with 192Ir source by using well type ionization chamber. Methods: The air kerma strength of 30 afterloading units with 192Ir source was measured using 2000A electrometer and 1000 plus well type ionization chamber, and apparent activity of the source was calculated with the air kerma strength and apparent activity conversion factor. The measured activity of the source was compared with the original value of the source provided by the manufacturer, and the relevant deviation should be within ±5%. Results: The air kerma strength of afterloading units with 192Ir sources was tested. The relevant deviation of the measured activity and the original value was within -0.1%-4.4%. Conclusions: The measurement method with a well type ionization chamber is convenient and highly accurate which can be used for the test of quality control in hospitals. (authors)

  7. Determination of the tissue inhomogeneity correction in high dose rate Brachytherapy for Iridium-192 source

    Barlanka Ravikumar

    2012-01-01

    Full Text Available In Brachytherapy treatment planning, the effects of tissue heterogeneities are commonly neglected due to lack of accurate, general and fast three-dimensional (3D dose-computational algorithms. In performing dose calculations, it is assumed that the tumor and surrounding tissues constitute a uniform, homogeneous medium equivalent to water. In the recent past, three-dimensional computed tomography (3D-CT based treatment planning for Brachytherapy applications has been popularly adopted. However, most of the current commercially available planning systems do not provide the heterogeneity corrections for Brachytherapy dosimetry. In the present study, we have measured and quantified the impact of inhomogeneity caused by different tissues with a 0.015 cc ion chamber. Measurements were carried out in wax phantom which was employed to measure the heterogeneity. Iridium-192 (192 Ir source from high dose rate (HDR Brachytherapy machine was used as the radiation source. The reduction of dose due to tissue inhomogeneity was measured as the ratio of dose measured with different types of inhomogeneity (bone, spleen, liver, muscle and lung to dose measured with homogeneous medium for different distances. It was observed that different tissues attenuate differently, with bone tissue showing maximum attenuation value and lung tissue resulting minimum value and rest of the tissues giving values lying in between those of bone and lung. It was also found that inhomogeneity at short distance is considerably more than that at larger distances.

  8. Source position verification and dosimetry in HDR brachytherapy using an EPID

    Purpose: Accurate treatment delivery in high dose rate (HDR) brachytherapy requires correct source dwell positions and dwell times to be administered relative to each other and to the surrounding anatomy. Treatment delivery inaccuracies predominantly occur for two reasons: (i) anatomical movement or (ii) as a result of human errors that are usually related to incorrect implementation of the planned treatment. Electronic portal imaging devices (EPIDs) were originally developed for patient position verification in external beam radiotherapy and their application has been extended to provide dosimetric information. The authors have characterized the response of an EPID for use with an 192Ir brachytherapy source to demonstrate its use as a verification device, providing both source position and dosimetric information.Methods: Characterization of the EPID response using an 192Ir brachytherapy source included investigations of reproducibility, linearity with dose rate, photon energy dependence, and charge build-up effects associated with exposure time and image acquisition time. Source position resolution in three dimensions was determined. To illustrate treatment verification, a simple treatment plan was delivered to a phantom and the measured EPID dose distribution compared with the planned dose.Results: The mean absolute source position error in the plane parallel to the EPID, for dwells measured at 50, 100, and 150 mm source to detector distances (SDD), was determined to be 0.26 mm. The resolution of the z coordinate (perpendicular distance from detector plane) is SDD dependent with 95% confidence intervals of ±0.1, ±0.5, and ±2.0 mm at SDDs of 50, 100, and 150 mm, respectively. The response of the EPID is highly linear to dose rate. The EPID exhibits an over-response to low energy incident photons and this nonlinearity is incorporated into the dose calibration procedure. A distance (spectral) dependent dose rate calibration procedure has been developed. The

  9. Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detector

    Minamisawa, R. A.; Rubo, R. A.; Seraide, R. M.; Rocha, J. R. O.; Almeida, A. [Department of Physics and Mathematics, FFCLRP, University of Sao Paulo, 14040-901, Ribeirao Preto-SP (Brazil); INRAD, Medical School - University of Sao Paulo, Clinical Hospital (HCUSP), 05403-001, Sao Paulo-SP (Brazil); CAISM Radiotherapy Service, CEB, State University of Campinas, 13083-881, Campinas-SP (Brazil); Department of Physics and Mathematics, FFCLRP, University of Sao Paulo, 14040-901, Ribeirao Preto-SP (Brazil)

    2010-10-15

    Purpose: Several attempts to determine the transit time of a high dose rate (HDR) brachytherapy unit have been reported in the literature with controversial results. The determination of the source speed is necessary to accurately calculate the transient dose in brachytherapy treatments. In these studies, only the average speed of the source was measured as a parameter for transit dose calculation, which does not account for the realistic movement of the source, and is therefore inaccurate for numerical simulations. The purpose of this work is to report the implementation and technical design of an optical fiber based detector to directly measure the instantaneous speed profile of a {sup 192}Ir source in a Nucletron HDR brachytherapy unit. Methods: To accomplish this task, we have developed a setup that uses the Cerenkov light induced in optical fibers as a detection signal for the radiation source moving inside the HDR catheter. As the {sup 192}Ir source travels between two optical fibers with known distance, the threshold of the induced signals are used to extract the transit time and thus the velocity. The high resolution of the detector enables the measurement of the transit time at short separation distance of the fibers, providing the instantaneous speed. Results: Accurate and high resolution speed profiles of the {sup 192}Ir radiation source traveling from the safe to the end of the catheter and between dwell positions are presented. The maximum and minimum velocities of the source were found to be 52.0{+-}1.0 and 17.3{+-}1.2 cm/s. The authors demonstrate that the radiation source follows a uniformly accelerated linear motion with acceleration of |a|=113 cm/s{sup 2}. In addition, the authors compare the average speed measured using the optical fiber detector to those obtained in the literature, showing deviation up to 265%. Conclusions: To the best of the authors' knowledge, the authors directly measured for the first time the instantaneous speed

  10. Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detector

    Purpose: Several attempts to determine the transit time of a high dose rate (HDR) brachytherapy unit have been reported in the literature with controversial results. The determination of the source speed is necessary to accurately calculate the transient dose in brachytherapy treatments. In these studies, only the average speed of the source was measured as a parameter for transit dose calculation, which does not account for the realistic movement of the source, and is therefore inaccurate for numerical simulations. The purpose of this work is to report the implementation and technical design of an optical fiber based detector to directly measure the instantaneous speed profile of a 192Ir source in a Nucletron HDR brachytherapy unit. Methods: To accomplish this task, we have developed a setup that uses the Cerenkov light induced in optical fibers as a detection signal for the radiation source moving inside the HDR catheter. As the 192Ir source travels between two optical fibers with known distance, the threshold of the induced signals are used to extract the transit time and thus the velocity. The high resolution of the detector enables the measurement of the transit time at short separation distance of the fibers, providing the instantaneous speed. Results: Accurate and high resolution speed profiles of the 192Ir radiation source traveling from the safe to the end of the catheter and between dwell positions are presented. The maximum and minimum velocities of the source were found to be 52.0±1.0 and 17.3±1.2 cm/s. The authors demonstrate that the radiation source follows a uniformly accelerated linear motion with acceleration of |a|=113 cm/s2. In addition, the authors compare the average speed measured using the optical fiber detector to those obtained in the literature, showing deviation up to 265%. Conclusions: To the best of the authors' knowledge, the authors directly measured for the first time the instantaneous speed profile of a radiation source in a HDR

  11. Intraluminal hyperthermia and radiotherapy using {sup 192}Ir remote after loading system in the treatment of unresectable hilar bile duct cancer

    Tsuchida, Akira; Itoh, Masaki; Fujii, Tohru [Hiroshima Univ. (Japan). School of Medicine] [and others

    1995-10-01

    The efficacy of combined therapy of intraluminal hyperthermia and radiotherapy using remote after loading system (RALS) was compared with that of percutaneous transhepatic biliary endoprosthesis (PTBE) alone. The subjects were 60 patients having unresectable hilar bile duct cancer. Percutaneous transhepatic biliary drainage (PTBD) was performed in the all patients, and additionally PTBE in 39, local infusion of bleomycin and intraluminal hyperthermia in 11, and internal irradiation (RALS) in 10. Four fractionated irradiation (4 Gy x 4) was performed on the site 10 mm from the source using {sup 192}Ir high dose RALS, and subsequently two fractionated brachytherapy of 10 Gy and 20 fractionated external irradiation of 40 Gy. The outcome was significantly improved in the RALS group, showing 50% survival time of 444.8 days (PTBE group, 228.7 days; hyperthermia group, 472 days). (S.Y.).

  12. Fricke gel-layer dosimetry in high dose-rate brachytherapy

    Carrara, M. [Medical Physics Unit, Fondazione IRCCS ' Istituto Nazionale Tumori' , Via Venezian 1, I-20133 Milan (Italy); Fallai, C. [Radiotherapy Unit, Fondazione IRCCS ' Istituto Nazionale Tumori' , Via Venezian 1, I-20133 Milan (Italy); Gambarini, G. [Physics Department of the Universita degli Studi and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milan (Italy)], E-mail: grazia.gambarini@mi.infn.it; Negri, A. [Physics Department of the Universita degli Studi and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milan (Italy)

    2010-04-15

    The aim of this study was to evaluate the reliability of Fricke gel-layer dosimeters for the measurement of in-phantom dose distributions produced by a {sup 192}Ir brachytherapy source. The doses obtained were compared to measurements performed with thermoluminescent dosimeters and treatment planning calculations. Fricke gel-layer dosimeters have proven to be a promising tool to measure three-dimensional dose distributions in high dose-rate brachytherapy.

  13. Balloon-based adjuvant radiotherapy in breast cancer: comparison between 99mTc and HDR 192Ir*

    de Campos, Tarcísio Passos Ribeiro; de Lima, Carla Flavia; Cuperschmid, Ethel Mizrahy

    2016-01-01

    Objective To perform a comparative dosimetric analysis, based on computer simulations, of temporary balloon implants with 99mTc and balloon brachytherapy with high-dose-rate (HDR) 192Ir, as boosts to radiotherapy. We hypothesized that the two techniques would produce equivalent doses under pre-established conditions of activity and exposure time. Materials and Methods Simulations of implants with 99mTc-filled and HDR 192Ir-filled balloons were performed with the Siscodes/MCNP5, modeling in voxels a magnetic resonance imaging set related to a young female. Spatial dose rate distributions were determined. In the dosimetric analysis of the protocols, the exposure time and the level of activity required were specified. Results The 99mTc balloon presented a weighted dose rate in the tumor bed of 0.428 cGy.h-1.mCi-1 and 0.190 cGyh-1.mCi-1 at the balloon surface and at 8-10 mm from the surface, respectively, compared with 0.499 and 0.150 cGyh-1.mCi-1, respectively, for the HDR 192Ir balloon. An exposure time of 24 hours was required for the 99mTc balloon to produce a boost of 10.14 Gy with 1.0 Ci, whereas only 24 minutes with 10.0 Ci segments were required for the HDR 192Ir balloon to produce a boost of 5.14 Gy at the same reference point, or 10.28 Gy in two 24-minutes fractions. Conclusion Temporary 99mTc balloon implantation is an attractive option for adjuvant radiotherapy in breast cancer, because of its availability, economic viability, and similar dosimetry in comparison with the use of HDR 192Ir balloon implantation, which is the current standard in clinical practice. PMID:27141131

  14. Balloon-based adjuvant radiotherapy in breast cancer: comparison between {sup 99m}Tc and HDR {sup 192}Ir

    Campos, Tarcisio Passos Ribeiro de; Lima, Carla Flavia de; Cuperschmid, Ethel Mizrahy, E-mail: tprcampos@pq.cnpq.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2016-03-15

    Objective: To perform a comparative dosimetric analysis, based on computer simulations, of temporary balloon implants with {sup 99m}Tc and balloon brachytherapy with high-dose-rate (HDR) {sup 192}Ir, as boosts to radiotherapy. We hypothesized that the two techniques would produce equivalent doses under pre-established conditions of activity and exposure time. Materials and methods: simulations of implants with {sup 99m}Tc-filled and HDR {sup 192}Ir-filled balloons were performed with the Siscodes/MCNP5, modeling in voxels a magnetic resonance imaging set related to a young female. Spatial dose rate distributions were determined. In the dosimetric analysis of the protocols, the exposure time and the level of activity required were specified. Results: the {sup 99m}Tc balloon presented a weighted dose rate in the tumor bed of 0.428 cGy.h{sup -1}.mCi{sup -1} and 0.190 cGyh{sup -1} at the balloon surface and at 8-10 mm from the surface, respectively, compared with 0.499 and 0.150 cGyh{sup -1}.mCi{sup -1}, respectively, for the HDR {sup 192}Ir balloon. An exposure time of 24 hours was required for the {sup 99m}Tc balloon to produce a boost of 10.14 Gy with 1.0 Ci, whereas only 24 minutes with 10.0 Ci segments were required for the HDR {sup 192}Ir balloon to produce a boost of 5.14 Gy at the same reference point, or 10.28 Gy in two 24-minutes fractions. Conclusion: temporary {sup 99m}Tc balloon implantation is an attractive option for adjuvant radiotherapy in breast cancer, because of its availability, economic viability, and similar dosimetry in comparison with the use of HDR {sup 192}Ir balloon implantation, which is the current standard in clinical practice. (author)

  15. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the VSL and the BIPM

    Alvarez, J.T.; De Pooter, J.A.; Andersen, Claus E.;

    2014-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate brachytherapy sources of the Dutch Metrology Institute (VSL), The Netherlands, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the VSL in November 2009. The comparison resu...

  16. SU-E-T-457: Design and Characterization of An Economical 192Ir Hemi-Brain Small Animal Irradiator

    Grams, M; Wilson, Z; Sio, T; Beltran, C; Tryggestad, E; Gupta, S; Blackwell, C; McCollough, K; Sarkaria, J; Furutani, K [Mayo Clinic, Rochester, MN (United States)

    2014-06-01

    Purpose: To describe the design and dosimetric characterization of a simple and economical small animal irradiator. Methods: A high dose rate 192Ir brachytherapy source from a commercially available afterloader was used with a 1.3 centimeter thick tungsten collimator to provide sharp beam penumbra suitable for hemi-brain irradiation of mice. The unit is equipped with continuous gas anesthesia to allow robust animal immobilization. Dosimetric characterization of the device was performed with Gafchromic film. The penumbra from the small animal irradiator was compared under similar collimating conditions to the penumbra from 6 MV photons, 6 MeV electrons, and 20 MeV electrons from a linear accelerator as well as 300 kVp photons from an orthovoltage unit and Monte Carlo simulated 90 MeV protons. Results: The tungsten collimator provides a sharp penumbra suitable for hemi-brain irradiation, and dose rates on the order of 200 cGy/minute were achieved. The sharpness of the penumbra attainable with this device compares favorably to those measured experimentally for 6 MV photons, and 6 and 20 MeV electron beams from a linear accelerator. Additionally, the penumbra was comparable to those measured for a 300 kVp orthovoltage beam and a Monte Carlo simulated 90 MeV proton beam. Conclusions: The small animal irradiator described here can be built for under $1,000 and used in conjunction with any commercial brachytherapy afterloader to provide a convenient and cost-effective option for small animal irradiation experiments. The unit offers high dose rate delivery and sharp penumbra, which is ideal for hemi-brain irradiation of mice. With slight modifications to the design, irradiation of sites other than the brain could be accomplished easily. Due to its simplicity and low cost, the apparatus described is an attractive alternative for small animal irradiation experiments requiring a sharp penumbra.

  17. SU-E-T-457: Design and Characterization of An Economical 192Ir Hemi-Brain Small Animal Irradiator

    Purpose: To describe the design and dosimetric characterization of a simple and economical small animal irradiator. Methods: A high dose rate 192Ir brachytherapy source from a commercially available afterloader was used with a 1.3 centimeter thick tungsten collimator to provide sharp beam penumbra suitable for hemi-brain irradiation of mice. The unit is equipped with continuous gas anesthesia to allow robust animal immobilization. Dosimetric characterization of the device was performed with Gafchromic film. The penumbra from the small animal irradiator was compared under similar collimating conditions to the penumbra from 6 MV photons, 6 MeV electrons, and 20 MeV electrons from a linear accelerator as well as 300 kVp photons from an orthovoltage unit and Monte Carlo simulated 90 MeV protons. Results: The tungsten collimator provides a sharp penumbra suitable for hemi-brain irradiation, and dose rates on the order of 200 cGy/minute were achieved. The sharpness of the penumbra attainable with this device compares favorably to those measured experimentally for 6 MV photons, and 6 and 20 MeV electron beams from a linear accelerator. Additionally, the penumbra was comparable to those measured for a 300 kVp orthovoltage beam and a Monte Carlo simulated 90 MeV proton beam. Conclusions: The small animal irradiator described here can be built for under $1,000 and used in conjunction with any commercial brachytherapy afterloader to provide a convenient and cost-effective option for small animal irradiation experiments. The unit offers high dose rate delivery and sharp penumbra, which is ideal for hemi-brain irradiation of mice. With slight modifications to the design, irradiation of sites other than the brain could be accomplished easily. Due to its simplicity and low cost, the apparatus described is an attractive alternative for small animal irradiation experiments requiring a sharp penumbra

  18. A brachytherapy procedure for carcinoma of the mobile tongue with small source high dose rate remote afterloading method

    Interstitial brachytherapy was conducted for mobile tongue carcinoma using a new high dose rate remote afterloading machine (microSelectron-HDR) with small 192Ir source. A detailed method was described, approaching from submandibular skin by open-ended stainless steel needles to the tongue lesion, and replacing each needle into flexible nylon tube from the oral cavity. We deal with a new Linked Double-Button technique and treatment policy in this paper. Complete local control was obtained in all 7 patients applied as of February 1992, up to 9-months follow-up, and quality of life of patients after this method was proved as good as that in low dose rate procedure. (author)

  19. Endovascular brachytherapy: dosimetry and dose-area analysis of various radiation sources

    With the increase in popularity of endovascular brachytherapy for prevention of restenosis following coronary angioplasty, it remains to be determined which isotope and isotope form is the most ideal. An issue concerning the use of wire sources is the influence of the centering of the wire on dose uniformity across the artery wall and the potential problems this can lead to in terms of underdosage of the target tissues. In this investigation, the dosimetric characteristics of three currently used sources (γ-emitting 192Ir wire; β-emitting 32P wire; and β-emitting 188Re solution) were determined with EGS4 Monte Carlo. The dose results were then used to determine the dose-area relationships for the three sources in arteries with concentric and non-concentric lumens/walls, including situations in which the wire sources are moved away from the centre of the artery. It is found that, in order to ensure dose uniformity, centering is substantially more important for β-emitting wire sources. This is highlighted most significantly in the case of an example large irregular artery. Although the suitability of a source depends on many criteria (e.g., cost, availability, radiation protection, possible radiation-induced late effects), the problem of centering a wire source in possibly large and/or irregular arteries is greatly eased by the use of a γ-emitting source. Copyright (2001) Australasian College of Physical Scientists and Engineers in Medicine

  20. Radiation Protection in Brachytherapy. Report of the SEFM Task Group on Brachytherapy

    This document presents the report of the Brachytherapy Task Group of the Spanish Society of Medical Physics. It is dedicated to the radiation protection aspects involved in brachytherapy. The aim of this work is to include the more relevant aspects related to radiation protection issues that appear in clinical practice, and for the current equipment in Spain. Basically this report focuses on the typical contents associated with high dose rate brachytherapy with 192Ir and 60Co sources, and permanent seed implants with 125I, 103Pd and 131Cs, which are the most current and widespread modalities. Ophthalmic brachytherapy (COMS with 125I, 106Ru, 90Sr) is also included due to its availability in a significant number of spanish hospitals. The purpose of this report is to assist to the medical physicist community in establishing a radiation protection program for brachytherapy procedures, trying to solve some ambiguities in the application of legal requirements and recommendations in clinical practice. (Author)

  1. Near-catheter dosimetry of a HDR brachytherapy source using Gafchromic film

    High dose rate intraluminal brachytherapy treatments can be delivered using as few as one or two afterloading catheters, delivering doses of up to 10 Gy at 10 mm, leading to high dose gradients and extreme hot spots close to the catheter. These conditions have the potential to damage the patient's health tissues, possibly leading to necrosis, or even death from uncontrolled bleeding. Ionisation chambers and solid state detectors are limited in their usefulness for near-catheter dosimetry because of their physical size and in some cases energy and dose rate dependence. In contrast, radiochromic film has a large dose–response range, excellent spatial resolution, near-energy independence for megavoltage photons and the ability to measure dose in two dimensions, making it ideal for this application. The aim of this study was to measure the location and relative magnitude of any dosimetric hot spots produced by a typical endobronchial treatment plan. The study also investigated the effect of the step size of the 192Ir source on both the dose hot spots and dose distribution. Our measurements show that for a typical single catheter treatment with 2.5 mm step size the maximum dose hot spots at the catheter surface are up to 37 times the prescription dose, up to 40 times for a 5 mm step size, and up to 46 times for a 10 mm step size. It is important that brachytherapy clinicians and physicists understand that hot spot magnitude increases with source step sizes and are aware of the risks associated with this form of brachytherapy treatment.

  2. RESULTS OF 192IR CONTACT RADIATION THERAPY FOR CERVIX UTERI CANCER

    O. A. Kravets

    2014-09-01

    Full Text Available The paper presents the results of treatment for locally advanced cervix uteri cancer, by applying a 192Ir radioactive source for contact radiation. Three- and five-year overall and relapse-free survival rates have been obtained for stages: 82.5 and 82.5%; 78.4 and 78.4% for Stage IIb; 57 and 52.3%; 41.6 and 41.6 for IIIb; 53.3 and 47.3%; 42.4 and 37.7% for IVb, respectively.

  3. Study of dose distributions in voxel phantoms for brachytherapy sources using the GEANT4 Monte Carlo toolkit

    This work studies the effects of corrections in the calculation of dose distribution for brachytherapy sources when they are inserted in a male human voxel phantom. The sources studied here are the Best Industries 125I 2301 model for low dose rate and the Amersham Buchler G0814 model 192Ir seed for high dose rate, in the simulation of prostate treatments. The presence of organs around the interest point scatters radiation in a different form than a water cube, the situation that is usually configured in these calculations. The insertion of the sources in an anthropomorphic phantom brings results closer to the real situation. The chosen phantom was the head and torso voxel phantom created by Zubal. The Geant4 Monte Carlo toolkit was used to simulate the radiation transportation along the source shielding and the human organs of the voxel phantom. After inserting the source in the phantom, the energy deposition in each voxel is computed, allowing the construction of isodose curves. The source insertion in the anthropomorphic phantom aims also at a further knowledge about the brachytherapy treatment planning and additional information such as the target volume dose and in neighbor organs, data that will be useful for medical staff working with this technique. (author)

  4. Procedures for calibration of brachytherapy sources

    Brachytherapy source strength verification is a responsibility of the user of these source, in fact of the Medical Physicists in charge of this issue in a Radiotherapy Service. The calibration procedures in the users conditions are shown. Specifics methods for source strength determination are recommended, both for High Dose Rate (HDR) sources with Remote Afterloading equipment and for Low Dose Rate sources. The The results of the calibration of HDR Remote After loaders are indicated

  5. Monte Carlo and experimental dosimetric study of the mHDR-v2 brachytherapy source

    Chandola Rakesh

    2010-01-01

    Full Text Available The conventional treatment planning system (TPS gives analytical calculations with ± 15 to 20% dose, which may lead to over exposure of critical organs or under dose of target. It is to obtain dose distribution parameters of nucletron high dose rate (HDR microselectron v2 (mHDR-v2 192 Ir brachytherapy source by experiment and by calculated study using Monte Carlo (MC EGSnrc code, and to find the similarity between them, and with any past study. To validate data, another MC GEANT4 study done in this work on the same source is also presented. Different software of the computer e.g. paint, excel, etc are employed for preparation of figures and graphs. The measured study of the source was done using an in-air ionization chamber, water phantom, and measurement set-up, while the calculated study was done by modeling the set up of the measured study by using the MC EGSnrc and GEANT4. Mean and probability are used in calculation of average values, and calculation of the uncertainties in result and discussion. The measured and calculated values of dose rate constant, radial dose function, and 2D anisotropy function were found to be in agreement with each other as well as with published data. The results of this study can be used as input to TPS.

  6. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy § 35.432 Calibration measurements of brachytherapy sources. (a) Before the first medical use of...

  7. 10 CFR 35.406 - Brachytherapy sources accountability.

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Brachytherapy sources accountability. 35.406 Section 35.406 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy § 35.406 Brachytherapy sources accountability. (a) A licensee shall maintain accountability at all...

  8. Guidelines for the calibration of low energy photon sources at beta-ray brachytherapy sources

    With the development of improved methods of implanting brachytherapy sources in a precise manner for treating prostate cancer and other disease processes, there has been a tremendous growth in the use of low energy photon sources, such as 125I and 103Pd brachytherapy seeds. Low energy photon sources have the advantage of easier shielding and also lowering the dose to normal tissue. However, the dose distributions around these sources are affected by the details in construction of the source and its encapsulation more than other sources used for brachytherapy treatments, such as 192Ir. With increasing number of new low energy photon sources on the market, care should be taken with regard to its traceability to primary standards. It cannot be assumed that a calibration factor for an ionization chamber that is valid for one type of low energy photon source, automatically is valid for another source even if both would use the same isotope. Moreover, the method used to calculate the dose must also take into account the structure of the source and the encapsulation. The dose calculation algorithm that is valid for one type of low energy source may not be valid for another source even if in both cases the same radionuclide is used. Simple ''point source'' approximations, i.e. where the source is modeled as a point, should be avoided, as such methods do not account for any details in the source construction. In this document, the dose calculation formalism adopted for low energy photon sources is that recommended by the American Association of Physicists in Medicine (AAPM) as outlined by Task Group-43 (TG-43). This method accounts for the source and capsule geometry. The AAPM recommends brachytherapy photon sources to be specified in terms of 'Air Kerma Strength' that is also used in the formalism mentioned above. On the other hand, the International Commission on Radiation Units and Measurements (ICRU) recommends that the specification be done in terms of Reference Air

  9. Assessment of radiation dose for surrounding organs and persons approaching implanted patients upon brachytherapy of prostate cancer with Iridium-192

    To assess a proper dose for radiation therapy fitting the typical physical characteristics of male Korean bodies, a mathematical phantom was prepared based on standard Korean male measurements. Upon brachytherapy of prostate cancer by implanting 192Ir into the prostate gland (the source organ), the absorbed dose of the prostate gland and surrounding organs and the expected dose of people within the vicinity were assessed. 192Ir, which has been the radionuclide of choice for prostate cancer brachytherapy, was selected for the simulation. It was assumed that 1 Ci of initial radioactivity would be administered. As a result, 1.28 E-02 Gy/Ci was exhibited in the prostate gland of the source organ, and the dose to which persons within the vicinity were exposed was exhibited to be 9.19 E-06 Sv at a distance of 30 cm from the front. (authors)

  10. Dosimetry of iridium-192 sources used in brachytherapy; Dosimetria de fontes de iridio-192 utilizadas em braquiterapia

    Henn, Keli Cristina

    1999-09-01

    The use of high dose rate brachytherapy (HDR) has been increasing in recent years, due to several advantages relative to conventional low dose rate brachytherapy, such as: shorter treatment times, the ability to fractionate treatment (and thus perform many treatments on an outpatient basis) and reduced worker exposures. Most HDR equipment uses small, high activity {sup 192} Ir sources, which are introduced into the patient using a remote system. The dose distribution around these sources is strongly dependent on the size and shape of the active volume and on the encapsulation of the source. The objective of this work is to compare two methods of calibrating sources of {sup 192} Ir, mamely, measurements in air with an ionization thimble chamber or with a well-type ionization chamber. In addition, we measured the anisotropy of the sources and made comparisons with values supplied by the manufacturer, since this factor is taken into account in the planning system algorithm when dose distributions are calculated. The dose was also evaluated at points of clinical interest (i.e. in the rectum and bladder) and compared to values obtained with the Nucletron PLATO-BPS planning system. The use of lead for rectal protection was evaluated in a cylindrical applicator, aiming the further development of a gynecological applicator. The results of the calibration of seven sources showed that the uncertainty in the calibration in a 'jig' system is smaller than 1%, compared to the value supplied by the source manufacturer. The differences between the results obtained with the well-type ionization camera and the 'jig' system were around 2%. The anisotropy showed good agreement with the values supplied by the manufacturer. The results show that the anisotropy factors, in air and water, are approximately constant and equal to 1.0, for angles between 70 deg and 150 deg. For angles smaller than 70 deg the anisotropy factor in water is larger than in air. Results are

  11. The use of TLDs for brachytherapy dosimetry

    Thermoluminescent dosimeters (TLDs) are routinely used to measure the dose around brachytherapy sources due to their small size and high precision. This work presents a concise overview of the use of LiF:Mg,Ti TLDs for brachytherapy dosimetry including the experimental procedures required to achieve high-precision measurements as well as new results regarding the intrinsic energy dependence with some of the commonly used brachytherapy sources. Equations to correct TLD light output to air kerma are outlined and a description of the method to determine the intrinsic energy dependence is presented. For the intrinsic energy dependence investigation, a review of previously published results is presented as well as new experimental results using 125I, 103Pd, 192Ir, and miniature x-ray brachytherapy sources at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The results of these experiments are consistent with previous work and give valuable insight to investigators using TLDs for brachytherapy measurements. - Highlights: • Brachytherapy measurements with LiF:Mg,Ti TLDs performed. • Intrinsic energy dependence for several brachytherapy sources determined. • New LiF:Mg,Ti energy dependence results compared with previous data for x-ray beams. • Uncertainty of LiF:Mg,Ti TLD measurements reviewed

  12. Brachytherapy

    ... News Physician Resources Professions Site Index A-Z Brachytherapy What is Brachytherapy and how is it used? ... will I feel during this procedure? What is brachytherapy and how is it used? Brachytherapy is a ...

  13. Samarium-145: a new brachytherapy source

    A new radiation source has been produced for brachytherapy, with radiation energies slightly above those of 125I, and a Tsub(1/2) of 340 d. This source, 145Sm, is produced by neutron irradiation of 144Sm (96.5% enriched). Decay is by electron capture with 140 K x-rays per 100 disintergrations in the energy region between 38-45 keV, plus 13 γ-rays at 61 keV. These sources are encapsulated in Ti tubes, approx. 0.8 mm x 4.5 mm, and have been developed for temporary implantation in brain and ocular tumours. The 38-61 keV photons should make such sources easy to shield, while providing a dose distribution from source arrays somewhat more homogeneous than that from 125I. In addition, the 340 d half life of 145Sm permits its use for times significantly longer than that of 60 d 125I. While the 145Sm sources have been designed primarily for implantation in a brain tumour, they should be useful for almost any conventional brachytherapy application. (author)

  14. The reference isodose length (RIL) in endovascular brachytherapy: physical aspects

    Full text: In a forthcoming recommendation of the endovascular GEC ESTRO (European Society for Therapeutic Radiology and Oncology) working group terms and concepts are defined for prescribing, reporting and recording lengths (volumes) for endovascular brachytherapy. Following these recommendation the reference isodose length (RIL) is one of the most important parameter for treatment planning. It is defined as the vessel length at the reference depth (1 or 2 mm) enclosed by the 90 % isodose. The RIL is thus a physical parameter to characterize a source configuration and depends on active source length (ASL), nuclide, source design, and reference depth. RILs are determined by (i) Monte Carlo calculations (EGSnrc code) and (ii) film dosimetry (radiochromic films + special phantom) for three endovascular brachytherapy devices currently in clinical use (192Ir: 23 mm ASL, 32P: 40 mm ASL, 90Sr: 40 mm ASL). The calculated RIL at 2 mm distance from the source axis are 15.4 mm, 36.8 mm and 35.8 mm for the 192Ir, 32P, 90Sr sources, respectively. The results obtained with EGSnrc are in very good agreement with the measured longitudinal dose profiles. The reference isodose length (RIL) is a useful and essential parameter in endovascular brachytherapy treatment planning, which critically depends on source design. Monte Carlo methods are a valuable tool to calculate/verify the RIL of different devices at the respective reference depth. (author)

  15. Performance assessment of the BEBIG MultiSource high dose rate brachytherapy treatment unit.

    Palmer, Antony; Mzenda, Bongile

    2009-12-21

    A comprehensive system characterisation was performed of the Eckert & Ziegler BEBIG GmbH MultiSource High Dose Rate (HDR) brachytherapy treatment unit with an (192)Ir source. The unit is relatively new to the UK market, with the first installation in the country having been made in the summer of 2009. A detailed commissioning programme was devised and is reported including checks of the fundamental parameters of source positioning, dwell timing, transit doses and absolute dosimetry of the source. Well chamber measurements, autoradiography and video camera analysis techniques were all employed. The absolute dosimetry was verified by the National Physical Laboratory, UK, and compared to a measurement based on a calibration from PTB, Germany, and the supplied source certificate, as well as an independent assessment by a visiting UK centre. The use of the 'Krieger' dosimetry phantom has also been evaluated. Users of the BEBIG HDR system should take care to avoid any significant bend in the transfer tube, as this will lead to positioning errors of the source, of up to 1.0 mm for slight bends, 2.0 mm for moderate bends and 5.0 mm for extreme curvature (depending on applicators and transfer tube used) for the situations reported in this study. The reason for these errors and the potential clinical impact are discussed. Users should also note the methodology employed by the system for correction of transit doses, and that no correction is made for the initial and final transit doses. The results of this investigation found that the uncorrected transit doses lead to small errors in the delivered dose at the first dwell position, of up to 2.5 cGy at 2 cm (5.6 cGy at 1 cm) from a 10 Ci source, but the transit dose correction for other dwells was accurate within 0.2 cGy. The unit has been mechanically reliable, and source positioning accuracy and dwell timing have been reproducible, with overall performance similar to other existing HDR equipment. The unit is capable of high

  16. Calibration of photon and beta ray sources used in brachytherapy. Guidelines on standardized procedures at Secondary Standards Dosimetry Laboratories

    It has generally been recognized that international harmonization in radiotherapy dosimetry is essential. Consequently, the IAEA has given much effort to this, for example by publishing a number of reports in the Technical Reports Series (TRS) for external beam dosimetry, most notably TRS-277 and more recently TRS-398. Both of these reports describe in detail the steps to be taken for absorbed dose determination in water and they are often referred to as 'dosimetry protocols'. Similar to TRS-277, it is expected that TRS-398 will be adopted or used as a model by a large number of countries as their national protocol. In 1996, the IAEA established a calibration service for low dose rate (LDR) 137 Cs brachytherapy sources, which is the most widely used source for treatment of gynecological cancer. To further enhance harmonization in brachytherapy dosimetry, the IAEA published in 1999 IAEA-TECDOC-1079 entitled 'Calibration of Brachytherapy Sources. Guidelines on Standardized Procedures for the Calibration of Brachytherapy Sources at Secondary Standard Dosimetry Laboratories (SSDLs) and Hospitals'. The report was well received and was distributed in a large number of copies to the members of the IAEA/WHO network of SSDLs and to medical physicists working with brachytherapy. The present report is an update of the aforementioned TECDOC. Whereas TECDOC-1079 described methods for calibrating brachytherapy sources with photon energies at or above those of 192Ir, the current report has a wider scope in that it deals with standardization of calibration of all the most commonly used brachytherapy sources, including both photon and beta emitting sources. The latter sources have been in use for a few decades already, but their calibration methods have been unclear. Methods are also described for calibrating sources used in the rapidly growing field of cardiovascular angioplasty. In this application, irradiation of the vessel wall is done in an attempt to prevent restenosis after

  17. Comparison of TG-43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes.

    Zaker, Neda; Zehtabian, Mehdi; Sina, Sedigheh; Koontz, Craig; S Meigooni, Ali

    2016-01-01

    Monte Carlo simulations are widely used for calculation of the dosimetric param-eters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross-sectional library for the purpose of simulat-ing different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross-sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in 125I and 103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code - MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low-energy sources such as 125I and 103Pd there are discrepancies in gL(r) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for 103Pd and 10 cm for 125I from the source, respectively. However, for higher energy sources, the discrepancies in gL(r) values are less than 1.1% for 192Ir and less than 1.2% for 137Cs between the three codes. PMID:27074460

  18. OER and RBE for 125I and 192Ir at low dose rate on mammalian cells

    The oxygen enhancement ratio (OER) for 125I and 192Ir as well as the relative biological effectiveness (RBE) at low dose rates (40-80 cGy h-1) were determined for B16 melanoma cells in culture. The OER was found to be 2.1±0.03 for 125I and 2.7±0.04 for 192Ir. The RBE for 125I relative to 192Ir was determined as 1.8±0.03 under aerated conditions and as 2.4±0.03 under hypoxia. 18 refs.; 5 figs.; 1 table

  19. Iridium-192 sources production for brachytherapy use

    The incidence of cancer increases every year in Brazil and turns out to be one of the most important causes of mortality. Some of the patients are treated with brachytherapy, a form of lesion treatment which is based on the insertion of sources into tumors, in this particular case, activated iridium wires. During this process, the ionizing radiation efficiently destroys the malignant cells. These iridium wires have a nucleus made out of an iridium-platinum alloy 20-30/70-80 of 0,1 mm in diameter either coated by platinum or encased in a platinum tube. The technique consists in irradiating the wire in the reactor neutron flux in order to produce iridium-192. The linear activity goes from 1 mCi/cm to 4 mCi/cm and the basic characteristic, which is required, is the homogeneity of the activation along the wire. It should not present a dispersion exceeding 5% on a wire measuring 50 cm in length, 0.5 mm or 0.3 mm in diameter. Several experiments were carried out in order to define the activation parameters. Wires from different origins were analyzed. It was concluded that United States of America and France wires were found to be perfectly adequate for brachytherapy purposes and have therefore been sent to specialized hospitals and successfully applied to cancer patients. Considering that the major purpose of this work is to make this product more accessible in Brazil, at a cost reflecting the Brazilian reality, the IPEN is promoting the preparation of iridium-192 sources to be used in brachytherapy, on a national level. (author)

  20. Dosimetric study for characterization of a postal system of quality control in brachytherapy; Estudo dosimetrico para caracterizacao de um sistema postal de controle de qualidade em braquiterapia

    Alves, Victor Gabriel Leandro, E-mail: vgalves@inca.gov.b [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil); Queiroz Filho, Pedro Pacheco de; Santos, Denison de Souza, E-mail: queiroz@ird.gov.b, E-mail: santosd@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Begalli, Marcia, E-mail: begalli@uerj.b [Universidade do Estado do Rio de Janeiro (IF/UERJ), RJ (Brazil). Inst. de Fisica

    2009-07-01

    This work presents a dosimetric study of a postal system, to be developed for measurements of brachytherapy. It was projected a PMMA phantom with orifices for insertion of the high dose {sup 192}Ir source and the T L dosemeters. The system was characterized with using of Monte Carlo simulations, using the dosimetric magnitudes defined at the T G-43 of AAPM, as function of radial dose g(f)

  1. 10 CFR 35.400 - Use of sources for manual brachytherapy.

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Use of sources for manual brachytherapy. 35.400 Section 35.400 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy § 35.400 Use of sources for manual brachytherapy. A licensee shall use only brachytherapy sources...

  2. Effect of chemical composition and density of the pelvic structure in intracavitary brachytherapy dosimetry

    High dose rate (HDR) and low dose rate (LDR) intracavitary brachytherapies dosimetry in clinical practice are typically performed by commercial treatment planning systems. However, these systems do not fully consider the heterogeneities present in the real structure of the patient. The aim of this work is to obtain isodose curves and surfaces around the usual array of sources used in LDR (137Cs) and HDR (192Ir) intracavitary brachytherapy by Monte Carlo simulation, considering the real anatomic structure, density and chemical composition of media and tissues from the female pelvic region. The structural information was obtained from computed tomography images in the DICOM format. A voxel phantom (VP) was developed to perform ionizing radiation transport, considering the gamma spectrum of 137Cs and 192Ir. The absorbed dose was computed within each voxel of 2x2x3 mm3. Four materials were considered in the VP-air, fat, muscle tissue and bone; however, one material per voxel was defined. Results show and quantify the effect of density and chemical composition of the medium on the absorbed dose distribution. According to them, the treatment planning systems underestimate the absorbed dose by 8% approximately for both radionuclides. In a heterogeneous medium, the absorbed dose distribution of 192Ir is more irregular than that of 137Cs but spatially better defined.

  3. Effect of chemical composition and density of the pelvic structure in intracavitary brachytherapy dosimetry

    Chavez-Aguilera, N. [Coordinacion de Investigacion y Estudios de Posgrado, Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n Esquina con Jesus Carranza, 50180 Toluca (Mexico); Departamento de Fisica Medica, Instituto Estatal de Cancerologia ' Dr. Arturo Beltran Ortega' , Acapulco, Guerrero (Mexico); Torres-Garcia, E., E-mail: etorresg@uaemex.m [Coordinacion de Investigacion y Estudios de Posgrado, Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n Esquina con Jesus Carranza, 50180 Toluca (Mexico); Mitsoura, E. [Coordinacion de Investigacion y Estudios de Posgrado, Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n Esquina con Jesus Carranza, 50180 Toluca (Mexico)

    2011-03-15

    High dose rate (HDR) and low dose rate (LDR) intracavitary brachytherapies dosimetry in clinical practice are typically performed by commercial treatment planning systems. However, these systems do not fully consider the heterogeneities present in the real structure of the patient. The aim of this work is to obtain isodose curves and surfaces around the usual array of sources used in LDR ({sup 137}Cs) and HDR ({sup 192}Ir) intracavitary brachytherapy by Monte Carlo simulation, considering the real anatomic structure, density and chemical composition of media and tissues from the female pelvic region. The structural information was obtained from computed tomography images in the DICOM format. A voxel phantom (VP) was developed to perform ionizing radiation transport, considering the gamma spectrum of {sup 137}Cs and {sup 192}Ir. The absorbed dose was computed within each voxel of 2x2x3 mm{sup 3}. Four materials were considered in the VP-air, fat, muscle tissue and bone; however, one material per voxel was defined. Results show and quantify the effect of density and chemical composition of the medium on the absorbed dose distribution. According to them, the treatment planning systems underestimate the absorbed dose by 8% approximately for both radionuclides. In a heterogeneous medium, the absorbed dose distribution of {sup 192}Ir is more irregular than that of {sup 137}Cs but spatially better defined.

  4. Calibration procedure for thermoluminescent dosemeters in water absorbed doses for Iridium-192 high dose rate sources

    Thermoluminescent dosimeters are used in brachytherapy services quality assurance programs, with the aim of guaranteeing the correct radiation dose supplied to cancer patients, as well as with the purpose of evaluating new clinical procedures. This work describes a methodology for thermoluminescent dosimeters calibration in terms of absorbed dose to water for 192Ir high dose rate sources. The reference dose used is measured with an ionization chamber previously calibrated for 192Ir energy quality, applying the methodology proposed by Toelli. This methodology aims to standardizing the procedure, in a similar form to that used for external radiotherapy. The work evolves the adaptation of the TRS-277 Code of the International Atomic Energy Agency, for small and big cavities, through the introduction for non-uniform experimental factor, for the absorbed dose in the neighborhood of small brachytherapy sources. In order to simulate a water medium around the source during the experimental work, an acrylic phantom was used. It guarantees the reproducibility of the ionization chamber and the thermoluminescent dosimeter's location in relation to the radiation source. The values obtained with the ionization chamber and the thermoluminescent dosimeters, exposed to a 192Ir high dose rate source, were compared and correction factors for different source-detector distances were determined for the thermoluminescent dosimeters. A numeric function was generated relating the correction factors and the source-detector distance. These correction factors are in fact the thermoluminescent dosimeter calibration factors for the 192Ir source considered. As a possible application of this calibration methodology for thermoluminescent dosimeters, a practical range of source-detector distances is proposed for quality control of 192Ir high dose rate sources. (author)

  5. Detection of 192Ir in ground level air in Ursvik 20 September 2004, with Quarterly report on measurements of radionuclides in ground level air in Sweden. Fourth quarter 2004

    The radioisotope 192Ir was found in the filter from Ursvik, Monday 20 September 2004. There were no indications of 192Ir in filters from any of the other national stations during that period. The measured activity concentration of 192Ir was about 50 μBq/m, corresponding to a total collected activity of 2.36 Bq of 192Ir in the filter. The source of the release was the Studsvik Nuclear AB production site about 80 km south of Ursvik and the preliminary estimation of released activity was 58 kBq. Locally performed measurements and dispersion calculations show that the released amount of 192Ir was in the order of 1 GBq. This is in agreement both with the measurements at the filter station in Ursvik, and with the dispersion calculations performed by FOI. Filtering of ground level air is performed weekly at six different locations in Sweden: Kiruna, Umeaa, Gaevle, Ursvik, Visby and Ljungbyhed. The filters are pressed and the contents of different radionuclides are measured by gamma spectroscopy. Precipitation is also collected at four of the stations: Kiruna, Gaevle, Ursvik and Ljungbyhed, the samples are ashed and the contents of radionuclides are measured. The levels of Be-7 and Cs-137 in air and precipitation are presented for the different stations. Other anthropogenic radionuclides detected, if any are also presented

  6. Establishment of in vitro 192Ir γ-ray dose-response relationship for dose assessment by the lymphocyte dicentric assay

    Kowalska, Maria; Meronka, Katarzyna; Szewczak, Kamil

    2012-03-01

    In vitro dose-response relationships are used to describe the relation between dicentric chromosomes and radiation dose for human peripheral blood lymphocytes. The dicentric yield depends on both the dose and the radiation quality. Thus, for reliable dose estimation in vitro dose responses must be determined for different radiation qualities. This paper reports the work for setting up the relationship for the dicentric production in the lymphocytes exposed in vitro to 192Ir g-rays at Central Laboratory for Radiological Protection (CLOR). In a case of a radiation accident in industrial radiography using 192Ir sealed sources, this will be the basis for the indirect evaluation of the g-ray dose to which an accidental victim was exposed.

  7. Dynamic rotating-shield brachytherapy

    Purpose: To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process.Methods: A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D90 for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and 192Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D2cc of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with α/β= 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively.Results: For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci192Ir source, and the average HR-CTV D90 was 78.9 Gy. In order to match the HR-CTV D90 of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D90 above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively.Conclusions: For cervical cancer patients, D

  8. Dynamic rotating-shield brachytherapy

    Liu, Yunlong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States); Flynn, Ryan T.; Kim, Yusung [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Yang, Wenjun [Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Wu, Xiaodong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)

    2013-12-15

    Purpose: To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process.Methods: A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D{sub 90} for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and {sup 192}Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D{sub 2cc} of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with α/β= 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively.Results: For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci{sup 192}Ir source, and the average HR-CTV D{sub 90} was 78.9 Gy. In order to match the HR-CTV D{sub 90} of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D{sub 90} above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively

  9. Comment on ‘Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy 125I and 192Ir sources and 60Co cell irradiation’

    Lindborg, Lennart; Lillhök, Jan; Grindborg, Jan-Erik

    2015-11-01

    The relative standard deviation, σr,D, of calculated multi-event distributions of specific energy for 60Co ϒ rays was reported by the authors F Villegas, N Tilly and A Ahnesjö (Phys. Med. Biol. 58 6149-62). The calculations were made with an upgraded version of the Monte Carlo code PENELOPE. When the results were compared to results derived from experiments with the variance method and simulated tissue equivalent volumes in the micrometre range a difference of about 50% was found. Villegas et al suggest wall-effects as the likely explanation for the difference. In this comment we review some publications on wall-effects and conclude that wall-effects are not a likely explanation.

  10. Reply to the comment on ‘Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy 125I and 192Ir sources and 60Co cell irradiation’

    Villegas, F.; Ahnesjö, A.

    2016-07-01

    A discrepancy between the Monte Carlo derived relative standard deviation σ z\\text{rel} (microdosimetric spread) and experimental data was reported by Villegas et al (2013 Phys. Med. Biol. 58 6149–62) suggesting wall effects as a plausible explanation. The comment by Lindborg et al (2015 Phys. Med. Biol. 60 8621–4) concludes that this is not a likely explanation. A thorough investigation of the Monte Carlo (MC) transport code used for track simulation revealed a critical bug. The corrected MC version yielded σ z\\text{rel} values that are now within experimental uncertainty. Other microdosimetric findings are hereby communicated.

  11. Calibration of photon and beta ray sources used in brachytherapy. Guidelines on standardized procedures at Secondary Standards Dosimetry Laboratories (SSDLs) and hospitals

    It has generally been recognized that international harmonization in radiotherapy dosimetry is essential. Consequently, the IAEA has given much effort to this, for example by publishing a number of reports in the Technical Reports Series (TRS) for external beam dosimetry, most notably TRS-277 and more recently TRS-398. Both of these reports describe in detail the steps to be taken for absorbed dose determination in water and they are often referred to as 'dosimetry protocols'. Similar to TRS-277, it is expected that TRS-398 will be adopted or used as a model by a large number of countries as their national protocol. In 1996, the IAEA established a calibration service for low dose rate (LDR) 137 Cs brachytherapy sources, which is the most widely used source for treatment of gynecological cancer. To further enhance harmonization in brachytherapy dosimetry, the IAEA published in 1999 IAEA-TECDOC-1079 entitled 'Calibration of Brachytherapy Sources. Guidelines on Standardized Procedures for the Calibration of Brachytherapy Sources at Secondary Standard Dosimetry Laboratories (SSDLs) and Hospitals'. The report was well received and was distributed in a large number of copies to the members of the IAEA/WHO network of SSDLs and to medical physicists working with brachytherapy. The present report is an update of the aforementioned TECDOC. Whereas TECDOC-1079 described methods for calibrating brachytherapy sources with photon energies at or above those of 192Ir, the current report has a wider scope in that it deals with standardization of calibration of all the most commonly used brachytherapy sources, including both photon and beta emitting sources. The latter sources have been in use for a few decades already, but their calibration methods have been unclear. Methods are also described for calibrating sources used in the rapidly growing field of cardiovascular angioplasty. In this application, irradiation of the vessel wall is done in an attempt to prevent restenosis after

  12. External beam irradiation plus 192Ir implant after breast-preserving surgery in women with early breast cancer

    Purpose: To provide more information for the clinician and to analyze the impact of the boost with brachytherapy on the local disease-free survival (LDFS), disease-free survival (DFS), specific overall survival (OS), and cosmesis, a retrospective study of external radiation therapy and 192Ir implantation in early breast cancer at Institut Catala d'Oncologia has been undertaken. Patients and Methods: From 1986 to 1996, 530 patients were selected for this study with a median follow-up period of 39.5 months (range, 10-115 months). External radiation therapy (combined with brachytherapy) was administered postoperatively to the breast in all patients. Mean given dose was 48.7 Gy (range, 42-52 Gy) with external radiation therapy to the breast, and 16.8 Gy (range, 10-27 Gy) was the mean dose with brachytherapy. Variables have been tested for cosmesis. Univariate and multivariate analysis have also been carried out. Results: Mean age of the patients was 54 years (range, 28-81 years). Stages were distributed as follows: 350 patients (66%) in Stage I, 173 in Stage II (32.8%), and 7 in Stage III (1.1%). Pathologic distribution was 445 patients with infiltrating ductal carcinoma (84%), 20 patients with infiltrating lobular carcinoma (4%), and 65 patients (12%) of a miscellaneous group. OS for the entire group was 89.4% and 85.9% at 5 and 7 years respectively. Probability of DFS was 81.7% and 70.1% at 5 and 7 years. The LDFS was 94.9% and 91.7% at 5 and 7 years. The MFS probability was 85.5% and 76.9% at 5 and 7 years, respectively. Univariate analysis demonstrated that age (older than 52 years), premenopausal status, moderate and high histologic grades (Grades II-III), and presence of intraductal comedocarcinoma were prognostic factors for local relapse. Multivariate analysis for local disease-free survival demonstrated that only perineural or muscular infiltration remain as prognostic factors. Tumor dose bed of 70 Gy or higher had a negative impact in breast subcutaneous

  13. Characterization of a Ce3+ doped SiO2 optical dosimeter for dose measurements in HDR brachytherapy

    Aim of this work was to study the application of a new miniaturized Ce3+ doped SiO2 scintillation detector to in vivo dosimetry in high dose rate brachytherapy. Energy, dose-rate, temperature and angular dependences of the detector response to 192Ir HDR brachytherapy fields were investigated, as well as sensitivity reproducibility and linearity. To this aim, two ad hoc phantoms were designed and developed to perform measurements in water. Intra-session reproducibility resulted to be very high, however inter-session reproducibility showed too high statistical variation. Detector response resulted to increase linearly with dose (R2 = 0.997), with no evidence of energy and dose-rate dependence. Sensitivity resulted to increase linearly with temperature (R2 = 0.995), with a 0.2% increase each °C. Finally, no significant angular dependence for the source moving around a circle in the azimuthal plane centered at the scintillator was observed. The obtained results show that the proposed detector is suitable for in vivo real-time dosimetry in high dose rate brachytherapy. -- Highlights: •A Ce3+ doped SiO2 scintillation detector was applied to 192Ir HDR brachytherapy. •Detector response resulted to be linear with the delivered dose. •No evidence of energy and dose rate dependence resulted from the study

  14. Parameterization of brachytherapy source phase space file for Monte Carlo-based clinical brachytherapy dose calculation

    A common approach to implementing the Monte Carlo method for the calculation of brachytherapy radiation dose deposition is to use a phase space file containing information on particles emitted from a brachytherapy source. However, the loading of the phase space file during the dose calculation consumes a large amount of computer random access memory, imposing a higher requirement for computer hardware. In this study, we propose a method to parameterize the information (e.g., particle location, direction and energy) stored in the phase space file by using several probability distributions. This method was implemented for dose calculations of a commercial Ir-192 high dose rate source. Dose calculation accuracy of the parameterized source was compared to the results observed using the full phase space file in a simple water phantom and in a clinical breast cancer case. The results showed the parameterized source at a size of 200 kB was as accurate as the phase space file represented source of 1.1 GB. By using the parameterized source representation, a compact Monte Carlo job can be designed, which allows an easy setup for parallel computing in brachytherapy planning. (paper)

  15. Parameterization of brachytherapy source phase space file for Monte Carlo-based clinical brachytherapy dose calculation

    Zhang, M.; Zou, W.; Chen, T.; Kim, L.; Khan, A.; Haffty, B.; Yue, N. J.

    2014-01-01

    A common approach to implementing the Monte Carlo method for the calculation of brachytherapy radiation dose deposition is to use a phase space file containing information on particles emitted from a brachytherapy source. However, the loading of the phase space file during the dose calculation consumes a large amount of computer random access memory, imposing a higher requirement for computer hardware. In this study, we propose a method to parameterize the information (e.g., particle location, direction and energy) stored in the phase space file by using several probability distributions. This method was implemented for dose calculations of a commercial Ir-192 high dose rate source. Dose calculation accuracy of the parameterized source was compared to the results observed using the full phase space file in a simple water phantom and in a clinical breast cancer case. The results showed the parameterized source at a size of 200 kB was as accurate as the phase space file represented source of 1.1 GB. By using the parameterized source representation, a compact Monte Carlo job can be designed, which allows an easy setup for parallel computing in brachytherapy planning.

  16. 10 CFR 35.490 - Training for use of manual brachytherapy sources.

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Training for use of manual brachytherapy sources. 35.490 Section 35.490 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy § 35.490 Training for use of manual brachytherapy sources. Except as provided in § 35.57, the...

  17. 10 CFR 35.2432 - Records of calibration measurements of brachytherapy sources.

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of calibration measurements of brachytherapy... Records § 35.2432 Records of calibration measurements of brachytherapy sources. (a) A licensee shall maintain a record of the calibrations of brachytherapy sources required by § 35.432 for 3 years after...

  18. [Brachytherapy].

    Itami, Jun

    2014-12-01

    Brachytherapy do require a minimal expansion of CTV to obtain PTV and it is called as ultimate high precision radiation therapy. In high-dose rate brachytherapy, applicators will be placed around or into the tumor and CT or MRI will be performed with the applicators in situ. With such image-guided brachytherapy (IGBT) 3-dimensional treatment planning becomes possible and DVH of the tumor and organs at risk can be obtained. It is now even possible to make forward planning satisfying dose constraints. Traditional subjective evaluation of brachytherapy can be improved to the objective one by IGBT. Brachytherapy of the prostate cancer, cervical cancer, and breast cancer with IGBT technique was described. PMID:25596048

  19. 21 CFR 892.5730 - Radionuclide brachytherapy source.

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radionuclide brachytherapy source. 892.5730 Section 892.5730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Therapeutic Devices § 892.5730 Radionuclide...

  20. Loss and recovery of an 192Ir gamma radiography exposure device

    A radiography exposure device containing 88.8 GBq (2.4 Ci) of 192Ir is inadvertently left in a taxi cab which has sped off before the equipment could be unloaded. The joint effort between the licensee and Philippine Nuclear Research Institute (PNRI) utilizing the tri-media in searching for the missing device resulted in its recovery 32 days later. The regulatory actions taken by the PNRI during and after the accident are discussed. (author). 3 refs

  1. Implementation of microsource high dose rate (mHDR) brachytherapy in developing countries

    Brachytherapy using remote afterloading of a single high dose rate 192Ir microsource was developed in the 1970s. After its introduction to clinics, this system has spread rapidly among developed Member States and has become a highly desirable modality in cancer treatment. This technique is now gradually being introduced to the developing Member States. The 192Ir sources are produced with a high specific activity. This results in a high dose rate (HDR) to the tumour and shorter treatment times. The high specific activity simultaneously results in a much smaller source (so-called micro source, around I mm in diameter) which may be easily inserted into tissue through a thin delivery tube, the so-called interstitial treatment, as well as easily inserted into body cavities, the so-called intracavitary or endoluminal treatment. Another advantage is the ability to change dwell time (the time a source remains in one position) of the stepping source which allows dose distribution to match the target volume more closely. The purpose of this TECDOC is to advise radiation oncologists, medical physicists and hospital administrators in hospitals which are planning to introduce 192Ir microsource HDR (mHDR) remote afterloading systems. The document supplements IAEA-TECDOC-1040, Design and Implementation of a Radiotherapy Programme: Clinical, Medical Physics, Radiation Protection and Safety Aspects, and will facilitate implementation of this new brachytherapy technology, especially in developing countries. The operation of the system, 'how to use the system', is not within the scope of this document. This TECDOC is based on the recommendations of an Advisory Group meeting held in Vienna in April 1999

  2. Experiences in Recycling and Reuse of Radioactive Sources in BRIT

    The Board of Radiation and Isotope Technology (BRIT), a unit of the Department of Atomic Energy in India, produces and supplies various types of sealed radiation sources in India. The sealed sources include teletherapy sources using 60Co, industrial radiography sources using 60Co and 192Ir, nucleonic gauging sources using 60Co, 137Cs, among others, and 137Cs brachytherapy sources. BRIT has acquired considerable experience in the reuse and recycling of these sealed sources. This has proved to be very useful in continuous control of these sources over the life cycle. (author)

  3. Size Effects of Gold and Iron Nanoparticles on Radiation Dose Enhancement in Brachytherapy and Teletherapy: A Monte Carlo Study

    Ahad Ollah Ezzati

    2014-08-01

    Full Text Available Introduction In this study, we aimed to calculate dose enhancement factor (DEF for gold (Au and iron (Fe nanoparticles (NPs in brachytherapy and teletherapy, using Monte Carlo (MC method. Materials and Methods In this study, a new algorithm was introduced to calculate dose enhancement by AuNPs and FeNPs for Iridium-192 (Ir-192 brachytherapy and Cobalt-60 (Co-60 teletherapy sources, using the MC method. In this algorithm, the semi-random distribution of NPs was used instead of the regular distribution. Diameters were assumed to be 15, 30, and 100 nm in brachytherapy and 15 and 30 nm in teletherapy. Monte Carlo MCNP4C code was used for simulations, and NP density values were 0.107 mg/ml and 0.112 mg/ml in brachytherapy and teletherapy, respectively. Results AuNPs significantly enhanced the radiation dose in brachytherapy (approximately 60%, and 100 nm diameter NPs showed the most uniform dose distribution. AuNPs had an insignificant effect on teletherapy radiation field, with a dose enhancement ratio of 3% (about the calculation uncertainty or less. In addition, FeNPs had an insignificant effect on both brachytherapy and teletherapy radiation fields. FeNPs dose enhancement was 3% in brachytherapy and 6% (about the calculation uncertainty or less in teletherapy. Conclusion It can be concluded that AuNPs can significantly increase the absorbed dose in brachytherapy; however, FeNPs do not have a noticeable effect on the absorbed dose

  4. MAGIC with formaldehyde applied to dosimetry of HDR brachytherapy source

    The use of polymer gel dosimeters in brachytherapy can allow the determination of three-dimensional dose distributions in large volumes and with high spatial resolution if an adequate calibration process is performed. One of the major issues in these experiments is the polymer gel response dependence on dose rate when high dose rate sources are used and the doses in the vicinity of the sources are to be determinated. In this study, the response of a modified MAGIC polymer gel with formaldehyde around an Iridium-192 HDR brachytherapy source is presented. Experimental results obtained with this polymer gel were compared with ionization chamber measurements and with Monte Carlo simulation with PENELOPE. A maximum difference of 3.10% was found between gel dose measurements and Monte Carlo simulation at a radial distance of 18 mm from the source. The results obtained show that the gel's response is strongly influenced by dose rate and that a different calibration should be used for the vicinity of the source and for regions of lower dose rates. The results obtained in this study show that, provided the proper calibration is performed, MAGIC with formaldehyde can be successfully used to accurate determinate dose distributions form high dose rate brachytherapy sources.

  5. Invited review, recent developments in brachytherapy source dosimetry

    Application of radioactive isotopes is the treatment of choice around the globe for many cancer sites. In this technique, the accuracy of the radiation delivery is highly dependent on the accuracy of radiation dosimetry around individual brachytherapy sources. Moreover, in order to have compatible clinical results, an identical method of source dosimetry must be employed across the world. This problem has been recently addressed by task group 43 from the American Association of Medical Physics with a protocol for dosimetric characterization of brachytherapy sources. This new protocol has been further updated using published data from international sources, by a new Task Group from the American Association of Medical Physics. This has resulted in an updated protocol known as TG43U1 that has been published in March 2004 issue of Medical Physics. The goal of this presentation is to review the original Task Group 43 protocol and associated algorithms for brachytherapy source dosimetry. In addition, the shortcomings of the original protocol that has been resolved in the updated recommendation will be highlighted. I am sure that this is not the end of the line and more work is needed to complete this task. I invite the scientists to join this task and complete the project, with the hope of much better clinical results for cancer patients

  6. Potential brachytherapy nuclides of future

    In the past there were relatively few radionuclides available for brachytherapy. But the situation is rapidly changing with the development of many new sources with properties that may be advantageous in certain clinical situations. In the choice of an acceptable, rather than an ideal radionuclide, it is important to consider the physical dose distribution, radiobiological effectiveness, ease of radiation protection, logistics and cost. Taking into account these factors, a number of radionuclides have been tried and more are being considered for specific type of applications. Presently, 137Cs is the most commonly used radionuclide for intracavitary therapy and 192Ir for interstitial therapy. 125I has more or less replaced 198Au for permanent implants. Clinical studies are being carried out to assess the feasibility of replacing 137Cs with 241Am for intracavitary applications and 125I with 103Pd and/or 169Yb for interstitial permanent implants. Other radionuclides being considered are 75Fe and 145Sm. Neutron induced brachytherapy is a new technique being tried to ensure complete radiation safety. (author). 1 tab

  7. SU-F-19A-10: Recalculation and Reporting Clinical HDR 192-Ir Head and Neck Dose Distributions Using Model Based Dose Calculation

    Purpose: To retrospectively re-calculate dose distributions for selected head and neck cancer patients, earlier treated with HDR 192Ir brachytherapy, using Monte Carlo (MC) simulations and compare results to distributions from the planning system derived using TG43 formalism. To study differences between dose to medium (as obtained with the MC code) and dose to water in medium as obtained through (1) ratios of stopping powers and (2) ratios of mass energy absorption coefficients between water and medium. Methods: The MC code Algebra was used to calculate dose distributions according to earlier actual treatment plans using anonymized plan data and CT images in DICOM format. Ratios of stopping power and mass energy absorption coefficients for water with various media obtained from 192-Ir spectra were used in toggling between dose to water and dose to media. Results: Differences between initial planned TG43 dose distributions and the doses to media calculated by MC are insignificant in the target volume. Differences are moderate (within 4–5 % at distances of 3–4 cm) but increase with distance and are most notable in bone and at the patient surface. Differences between dose to water and dose to medium are within 1-2% when using mass energy absorption coefficients to toggle between the two quantities but increase to above 10% for bone using stopping power ratios. Conclusion: MC predicts target doses for head and neck cancer patients in close agreement with TG43. MC yields improved dose estimations outside the target where a larger fraction of dose is from scattered photons. It is important with awareness and a clear reporting of absorbed dose values in using model based algorithms. Differences in bone media can exceed 10% depending on how dose to water in medium is defined

  8. SU-F-19A-10: Recalculation and Reporting Clinical HDR 192-Ir Head and Neck Dose Distributions Using Model Based Dose Calculation

    Carlsson Tedgren, A [Linkoping University, Linkoping, Linkoping (Sweden); Persson, M; Nilsson, J [Karolinska hospital, Stockholm, Stockholm (Sweden)

    2014-06-15

    Purpose: To retrospectively re-calculate dose distributions for selected head and neck cancer patients, earlier treated with HDR 192Ir brachytherapy, using Monte Carlo (MC) simulations and compare results to distributions from the planning system derived using TG43 formalism. To study differences between dose to medium (as obtained with the MC code) and dose to water in medium as obtained through (1) ratios of stopping powers and (2) ratios of mass energy absorption coefficients between water and medium. Methods: The MC code Algebra was used to calculate dose distributions according to earlier actual treatment plans using anonymized plan data and CT images in DICOM format. Ratios of stopping power and mass energy absorption coefficients for water with various media obtained from 192-Ir spectra were used in toggling between dose to water and dose to media. Results: Differences between initial planned TG43 dose distributions and the doses to media calculated by MC are insignificant in the target volume. Differences are moderate (within 4–5 % at distances of 3–4 cm) but increase with distance and are most notable in bone and at the patient surface. Differences between dose to water and dose to medium are within 1-2% when using mass energy absorption coefficients to toggle between the two quantities but increase to above 10% for bone using stopping power ratios. Conclusion: MC predicts target doses for head and neck cancer patients in close agreement with TG43. MC yields improved dose estimations outside the target where a larger fraction of dose is from scattered photons. It is important with awareness and a clear reporting of absorbed dose values in using model based algorithms. Differences in bone media can exceed 10% depending on how dose to water in medium is defined.

  9. Development and implementation of a remote audit tool for high dose rate (HDR) Ir-192 brachytherapy using optically stimulated luminescence dosimetry

    Purpose: The aim of this work was to create a mailable phantom with measurement accuracy suitable for Radiological Physics Center (RPC) audits of high dose-rate (HDR) brachytherapy sources at institutions participating in National Cancer Institute-funded cooperative clinical trials. Optically stimulated luminescence dosimeters (OSLDs) were chosen as the dosimeter to be used with the phantom.Methods: The authors designed and built an 8 × 8 × 10 cm3 prototype phantom that had two slots capable of holding Al2O3:C OSLDs (nanoDots; Landauer, Glenwood, IL) and a single channel capable of accepting all 192Ir HDR brachytherapy sources in current clinical use in the United States. The authors irradiated the phantom with Nucletron and Varian 192Ir HDR sources in order to determine correction factors for linearity with dose and the combined effects of irradiation energy and phantom characteristics. The phantom was then sent to eight institutions which volunteered to perform trial remote audits.Results: The linearity correction factor was kL= (−9.43 × 10−5× dose) + 1.009, where dose is in cGy, which differed from that determined by the RPC for the same batch of dosimeters using 60Co irradiation. Separate block correction factors were determined for current versions of both Nucletron and Varian 192Ir HDR sources and these vendor-specific correction factors differed by almost 2.6%. For the Nucletron source, the correction factor was 1.026 [95% confidence interval (CI) = 1.023–1.028], and for the Varian source, it was 1.000 (95% CI = 0.995–1.005). Variations in lateral source positioning up to 0.8 mm and distal/proximal source positioning up to 10 mm had minimal effect on dose measurement accuracy. The overall dose measurement uncertainty of the system was estimated to be 2.4% and 2.5% for the Nucletron and Varian sources, respectively (95% CI). This uncertainty was sufficient to establish a ±5% acceptance criterion for source strength audits under a formal RPC audit

  10. Verification of Oncentra brachytherapy planning using independent calculation

    Safian, N. A. M.; Abdullah, N. H.; Abdullah, R.; Chiang, C. S.

    2016-03-01

    This study was done to investigate the verification technique of treatment plan quality assurance for brachytherapy. It is aimed to verify the point doses in 192Ir high dose rate (HDR) brachytherapy between Oncentra Masterplan brachytherapy treatment planning system and independent calculation software at a region of rectum, bladder and prescription points for both pair ovoids and full catheter set ups. The Oncentra TPS output text files were automatically loaded into the verification programme that has been developed based on spreadsheets. The output consists of source coordinates, desired calculation point coordinates and the dwell time of a patient plan. The source strength and reference dates were entered into the programme and then dose point calculations were independently performed. The programme shows its results in a comparison of its calculated point doses with the corresponding Oncentra TPS outcome. From the total of 40 clinical cases that consisted of two fractions for 20 patients, the results that were given in term of percentage difference, it shows an agreement between TPS and independent calculation are in the range of 2%. This programme only takes a few minutes to be used is preferably recommended to be implemented as the verification technique in clinical brachytherapy dosimetry.

  11. Cs-137 brachytherapy sources calibration with well chamber

    This work describes the procedures and actions developed for the identification and reference air kerma rate (Sk) verification of Cs-137 sources used in gynecological brachytherapy practices. Following the IAEA TECDOC 1151 recommendations, the first stage consisted in designing the documentation required for the inventory and shipping registry of sources, along with the digital spreadsheets for calculating the decay and Sk of the sources at the moment of implantation. As a second stage, the Sk of sources was measured, following the low dose rate sources protocol advise, with a Standard Imaging HDR 1000 Plus well chamber calibrated at the University of Wisconsin SSDL. The documentation generated through this procedure allows identify each source clearly and uni-vocally. No significant differences were found between the Sk values obtained from the well chamber calibration procedure and those reported by the manufacturer in the corresponding certificates. The highest percent difference found was 2.3%. (author)

  12. Independent verification of the delivered dose in High-Dose Rate (HDR) brachytherapy

    An important aspect of a Quality Assurance program in Clinical Dosimetry is an independent verification of the dosimetric calculation done by the Treatment Planning System for each radiation treatment. The present paper is aimed at creating a spreadsheet for the verification of the dose recorded at a point of an implant with radioactive sources and HDR in gynecological injuries. An 192Ir source automatic differed loading equipment, GammaMedplus model, Varian Medical System with HDR installed at the Angel H. Roffo Oncology Institute has been used. The planning system implemented for getting the dose distribution is the BraquiVision. The sources coordinates as well as those of the calculation point (Rectum) are entered into the Excel-devised verification program by assuming the existence of a point source in each one of the applicators' positions. Such calculation point has been selected as the rectum is an organ at risk, therefore determining the treatment planning. The dose verification is performed at points standing at a sources distance having at least twice the active length of such sources, so they may be regarded as point sources. Most of the sources used in HDR brachytherapy with 192Ir have a 5 mm active length for all equipment brands. Consequently, the dose verification distance must be at least of 10 mm. (author)

  13. Dose effects of guide wires for catheter-based intravascular brachytherapy

    Purpose: Guide wires with high torquability and steerability are commonly used to navigate through a tortuous and/or branching arterial tree in a catheter-based intravascular brachytherapy procedure. The dosimetric effects due to the presence of metallic guide wires have not been addressed. This work investigates these dose effects for the three most commonly used β and γ sources (90Sr, 32P, and 192Ir). Methods and Materials: The EGS4 Monte Carlo codes were used to calculate the dose distributions for the 90Sr(NOVOSTE), 32P (Guidant), and 192Ir (BEST Ind.) with and without a guide wire in place. Energy spectra for particles exiting the sources were calculated from the full phase-space data obtained from the Monte Carlo simulations of the source constructions. Guide wires of various thicknesses and compositions were studied. Results: The dose perturbations due to the presence of guide wires were found to be far more significant for the 90Sr/90Y and 32P beta sources than those for the 192Ir gamma source. Because of the attenuation by the guide wires, a dose reduction of up to 60% behind a guide wire was observed for the beta sources, whereas the dose perturbation was found to be negligible for the γ source. For a β source, the dose perturbations depend on the thickness and the material of the guide wire. When the region behind a guide wire is part of an intravascular brachytherapy target, the presence of the guide wire results in a significant underdosing for β sources. The underdosed region can extend a few mm behind the guide wire and up to 1 mm in other directions. Conclusion: Significant dose perturbations by the presence of a metallic guide wire have been found in catheter-based intravascular brachytherapy using β sources. The dose effects should be considered in the dose prescription and/or in analyzing the treatment outcome for β sources. Such precautions are not necessary if using a gamma source

  14. Effective treatment of Stage I uterine papillary serous carcinoma with high dose-rate vaginal apex radiation (192Ir) and chemotherapy

    Purpose: Uterine papillary serous carcinoma (UPSC) is a morphologically distinct variant of endometrial carcinoma that is associated with a poor prognosis, high recurrence rate, frequent clinical understaging, and poor response to salvage treatment. We retrospectively analyzed local control, actuarial overall survival (OS), actuarial disease-free survival (DFS), salvage rate, and complications for patients with Federation International of Gynecology and Obstetrics (FIGO) (1988) Stage I UPSC. Methods and Materials: This retrospective analysis describes 38 patients with FIGO Stage I UPSC who were treated with the combinations of radiation therapy, chemotherapy, total abdominal hysterectomy, and bilateral salpingo-oophorectomy (TAH/BSO), with or without a surgical staging procedure. Twenty of 38 patients were treated with a combination of low dose-rate (LDR) uterine/vaginal brachytherapy using 226Ra or 137Cs and conventional whole-abdomen radiation therapy (WART) or whole-pelvic radiation therapy (WPRT). Of 20 patients (10%) in this treatment group, 2 received cisplatin chemotherapy. Eighteen patients were treated with high dose-rate (HDR) vaginal apex brachytherapy using 192Ir with an afterloading device and cisplatin, doxorubicin, and cyclophosphamide (CAP) chemotherapy (5 of 18 patients). Only 6 of 20 UPSC patients treated with combination LDR uterine/vaginal brachytherapy and conventional external beam radiotherapy underwent complete surgical staging, consisting of TAH/BSO, pelvic/para-aortic lymph node sampling, omentectomy, and peritoneal fluid analysis, compared to 15 of 18 patients treated with HDR vaginal apex brachytherapy. Results: The 5-year actuarial OS for patients with complete surgical staging and adjuvant radiation/chemotherapy treatment was 100% vs. 61% for patients without complete staging (p = 0.002). The 5-year actuarial OS for all Stage I UPSC patients treated with postoperative HDR vaginal apex brachytherapy and systemic chemotherapy was 94% (18

  15. Radiation Protection in Brachytherapy. Report of the SEFM Task Group on Brachytherapy; Proteccion radiologica en Braquiterapia. Informe del grupo de trabajo de Braquiterapia de la SEFM

    Perez-Calatayud, J.; Corredoira Silva, E.; Crispin Contreras, V.; Eudaldo Puell, T.; Frutos Baraja, J. de; Pino Sorroche, F.; Pujades Claumarchirant, M. C.; Richart Sancho, J.

    2015-07-01

    This document presents the report of the Brachytherapy Task Group of the Spanish Society of Medical Physics. It is dedicated to the radiation protection aspects involved in brachytherapy. The aim of this work is to include the more relevant aspects related to radiation protection issues that appear in clinical practice, and for the current equipment in Spain. Basically this report focuses on the typical contents associated with high dose rate brachytherapy with {sup 1}92Ir and {sup 6}0Co sources, and permanent seed implants with {sup 1}25I, {sup 1}03Pd and {sup 1}31Cs, which are the most current and widespread modalities. Ophthalmic brachytherapy (COMS with {sup 1}25I, {sup 1}06Ru, {sup 9}0Sr) is also included due to its availability in a significant number of spanish hospitals. The purpose of this report is to assist to the medical physicist community in establishing a radiation protection program for brachytherapy procedures, trying to solve some ambiguities in the application of legal requirements and recommendations in clinical practice. (Author)

  16. Calibration of brachytherapy sources. Guidelines on standardized procedures for the calibration of brachytherapy sources at Secondary Standard Dosimetry Laboratories (SSDLs) and hospitals

    Today, irradiation by brachytherapy is considered an essential part of the treatment for almost all the sites of cancer. With the improved localization techniques and treatment planning systems, it is now possible to have precise and reproducible dose delivery. However, the desired clinical results can only be achieved with a good clinical and dosimetric practice, i.e. with the implementation of a comprehensive quality assurance (QA) programme which includes detailed quality control procedures. As summarized in the present report, accidents in brachytherapy treatments have been caused due to the lack of traceable calibration of the sources, due to the incorrect use of quantities and units, or errors made in the dose calculation procedure. The International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources has established a requirement on the calibration of sources used for medical exposure. For sources used in brachytherapy treatments, a calibration traceable to a standards dosimetry laboratory is required. The present report deals with the calibration of brachytherapy sources and related quality control (QC) measurements, QC of ionization chambers and safety aspects related to the calibration procedures. It does not include safety aspects related to the clinical use of brachytherapy sources, which have been addressed in a recent IAEA publication, IAEA-TECDOC-1040, 'Design and Implementation of a Radiotherapy Programme: Clinical, Medical Physics, Radiation Protection and Safety Aspects'. The procedures recommended in this report yield traceability to internationally accepted standards. It must be realized, however, that a comprehensive QA programme for brachytherapy cannot rest on source calibration alone, but must ensure QC of all the equipment and techniques that are used for the dose delivery to the patient. The present publication incorporates the reports of several consultants meetings in the field of

  17. Brachytherapy surface mould: a treatment modality for some typical sites

    Brachytherapy techniques generally used are interstitial implants, intracavitary/intraluminal applications and surface mould therapy. At M.D. Oswal Cancer Hospital surface moulds with remote after-moulding system with 192Ir wires for treatment of some typical sites have been used

  18. Retreatment of recurrent carcinoma of the head and neck by afterloading interstitial 192Ir implant

    Emami, B.; Marks, J.E.

    1983-10-01

    From January 1975 to December 1980, 25 patients with persistent or recurrent carcinomas of the head and neck were retreated for palliation at the Division of Radiation Oncology, Mallinckrodt Institute of Radiology. These patients had all undergone extensive previous treatment by surgery and/or radiation. All were retreated with 192Ir interstitial implant with or without external radiation and/or surgical excision. Of 25 patients, 13 had complete response (CR) and 6 had partial response for a follow-up period of 1 to 7 years. Of 13 patients with CR, 6 are alive with no evidence of disease (NED) and two died NED. Detailed results are presented and the new strategy for such patients is discussed.

  19. Retreatment of recurrent carcinoma of the head and neck by afterloading interstitial 192Ir implant

    From January 1975 to December 1980, 25 patients with persistent or recurrent carcinomas of the head and neck were retreated for palliation at the Division of Radiation Oncology, Mallinckrodt Institute of Radiology. These patients had all undergone extensive previous treatment by surgery and/or radiation. All were retreated with 192Ir interstitial implant with or without external radiation and/or surgical excision. Of 25 patients, 13 had complete response (CR) and 6 had partial response for a follow-up period of 1 to 7 years. Of 13 patients with CR, 6 are alive with no evidence of disease (NED) and two died NED. Detailed results are presented and the new strategy for such patients is discussed

  20. Dosimetric characterization of low dose rate Iridium 192 wires used in interstitial brachytherapy, produced by Brachytherapy Sources Laboratory the CTRS/IPEN/CNEN-SP, Brazil

    In this work they were some dosimetric parameters established by the dosimetry protocol AAPM TG-43 for the thread of 192Ir with the purpose of complementing the dosimetric specifications of an original source produced at the country. For so much quantities such as the constant of dose rate, A , function of radial dose, g(r), and anisotropy function, F(r,θ), they were experimentally determined and the geometry function, G(r,θ), it was calculated. Measurements with TLD of LiF, with dimensions of 1 mm X 1 mm X 1 mm, was made in a phantom made of 5 plates of solid water RW3 material with dimensions of 300 mm X 300 mm X 10 mm, where it was obtained values of dose rate for some radial distances of the source, between 10 and 100 mm, to for an angle of 90 deg, for g(r), and also for other angles between 0 deg and 180 deg for F(r,θ). Threads of 192Ir were studied in the lengths of 10 mm, 20 mm, 30 mm, 50 mm and 100 mm. The stored energy on the thermoluminescent dosimeters was integrated by means of a TLD reader Harshaw 2000 meantime into a cycle of thermal treatment to which the thermoluminescent dosimeters was submitted being, 400 C in an interval of time of 1 hour proceeded immediately for more 2 hours to 105 C, after this treatment the thermoluminescent dosimeters was irradiated; even so, before the reading the detectors was still warm to 105 deg C for 10 minutes. The constant of dose rate for the threads of 192Ir of 10 mm, 20 mm, 30 mm, 50 mm and 100 mm are (1,076 =- 3,7%); (0,931 =- 3,7%); (0,714 =- 3,7%); (0,589 =-3,7%) and (0,271 =- 3,7%) cGyh-1 U-1, respectively (1U = unit of kerma intensity in the air = 1mGy m2 h-1 = 1cGy cm2 h-1). The results obtained for g(r) and F(r,θ) have uncertainties of (=- 4,5%) and they are compared with values obtained by Monte Carlo simulation and also for other values presented in the literature. (author)

  1. Synthesis of phosphosilicate matrix for application to brachytherapy sources

    Brachytherapy with beta sources can be useful for in situ radiotherapy of cancers where tiny radioactive seeds are injected directly into the tumor. Phosphorus 31P can be activated to b-emitter 32P by neutron activation with a half-life of 14.3 days. In this work, phosphosilicate matrices were synthesized through sol-gel process by hydrolysis and condensation of the tetraethylorthosilicate (TEOS) under two different conditions of synthesis. In both conditions the phosphoric acid and drying control chemical additives (DCCA's) were the same. Three drying control chemical additives were utilized: propylene carbonate, N,N-dimethylformamide and ethylene glycol. The casting solutions were prepared with phosphorus content of 3.2 wt.% and xerogels were thermally treated at 900 deg C. Different microstructures were observed under different conditions of synthesis. The microstructures of phosphosilicate matrices obtained with ethylene glycol and without DCCA's have shown the presence of a globular structure regions with large amount of phosphorous. (author)

  2. Brachytherapy with 125-Iodine sources: transport and radiation protection

    The estimates for the year 2009 show that 466,730 new cancer cases will occur in Brazil. Prostate cancer is the second most incident type. Brachytherapy, a type of radiotherapy, with Iodine-125 sources are an important form of treatment for this kind of cancer. The Instituto de Pesquisas Energeticas e Nucleares (IPEN) created a project to develop a national prototype of these sources and is implementing a facility for local production. The seeds manufacture in Brazil will allow to diminish the treatment cost and make it possible for a larger number of patients. While the laboratory is not ready, the IPEN import and it distributes seeds. This work aim is to present and evaluate the transport procedures and the radiological protection applied to imported sources in order to assist the procedures for the new laboratory implementation. Before sending to hospitals, the seeds are packed by a radioprotector supervisor, in accordance with CNEN NE 5.01 standard 'Radioactive Material Transport'. Despite Iodine-125 presents low energy photons, around 29 keV, local and personal dosimeters are used during the transport process, as described in CNEN NN 3.01 standard 'Radiological Protection Basic Guideline'. All the results show no contamination and very low exposure, proving the method to be valid. The transport procedure used is correct, according to the regulations. As an result of this work, a new dosimeter should be installed and evaluate in future study. (author)

  3. Holmium-166-DTPA as a liquid source for endovascular brachytherapy

    Liquid radiation sources with β emitters have advantages of accurate positioning and uniform dose distribution to the vessel walls to prevent the restenosis of coronary artery. As a liquid radiation source, 166Ho-DTPA was prepared and evaluated its in-vivo pharmacokinetic behavior through animal studies. 166Ho-DTPA was prepared by simple mixing the Holmium with DTPA at room temperature. The radiolabelling yield was 100% when the DTPA/Holmium molar ratio was >2. Radiolabelling of 166Ho-DTPA was not dependent on the pH range of 1.7-7.5. High radiochemical stability (>98%) was maintained over a period of 6 hours even with a radioactivity (∼11.1 GBq/12 mg of DTPA) stored at room temperature. Biodistribution of 166Ho-DTPA in rats and gamma camera images in rabbits showed that 166Ho-DTPA was quickly excreted via the urinary system. The average of Tmax and T1/2 of 166Ho-DTPA in the kidneys of rabbits were 3.71 ± 1.18 min and 9.15 ± 3.15 min. 166Ho-DTPA is a potential liquid radiation source for radiation brachytherapy to prevent the restenosis of the coronary artery using a liquid-filled balloon

  4. A Scintillating Fiber Dosimeter for Radiology and Brachytherapy with photodiode readout

    Rêgo, Florbela; Abreu, Maria da Conceição

    2011-01-01

    Purpose: For more than a decade that plastic optical fiber based dosimeters have been developed for medical applications. The feasibility of dosimeters using optical fibers that are almost Cherenkov light free has been demonstrated in some prototypes, particularly suitable for photon high-energy beams. In the energy range up to a few hundred keV, where the production of Cherenkov light by secondary electrons is negligible or small, the largest source of background are the fluorescence mechanisms. Methods: In recent years our group has developed an optical fiber dosimeter with photodiode readout named DosFib, which has small energy dependence in the range below 100 keV relevant for radiology. Photodiodes are robust photodetectors, presenting good stability over time and enough sensitivity to allow the use of an electrometer as a measuring device without extra electronics. Results: In-vitro tests using a High Dose Rate 192Ir source have demonstrated its suitability for brachytherapy applications using this impo...

  5. Evaluation of organ doses in brachytherapy treatment of uterus cancer using mathematical reference Indian adult phantom

    Quantifying organ dose to healthy organs during radiotherapy is essential to estimate the radiation risk. Dose factors are generated by simulating radiation transport through an anthropomorphic mathematical phantom representing a reference Indian adult using the Monte Carlo method. The mean organ dose factors (in mGy min-1 GBq-1) are obtained considering the Micro Selectron 192Ir source and BEBIG 60Co sources in the uterus of a reference Indian adult female phantom. The present study provides the factors for mean absorbed dose to organs applicable to the Indian female patient population undergoing brachytherapy treatment of uterus cancer. This study also includes a comparison of the dimension of organs in the phantom model with measured values of organs in the various investigated patients. (author)

  6. Progress and review of brachytherapy for cancer of the oral region

    Radiation therapy contributes greatly to the treatment of head and neck cancer, because it maintains the normal anatomy, minimizes functional loss, and facilitates a patient's return to work. Brachytherapy using small radiation sources is an indispensable modality for the treatment of cancer of the oral region, in which emphasis should be laid on the maintenance of normal anatomy and function and a high quality of life. Brachytherapy was performed in 62% of the radiation therapy patients with cancer of the oral region. Interstitial brachytherapy with radium, 192Ir-hairpin was administered to more than 80% of the patients with tongue cancer and 198Au-grain was frequently used for other site of the oral region. Introduction of the remote afterloading system (RALS) has completely eliminated the possibility of personnel exposure and increased the indication for brachytherapy. There is a lot of work to be done in the near future, including the establishment of dose-time relationship for RALS and the development of related apparatus and instruments and the standardization of dose assessment. (author)

  7. Dose-rate to water calibrations for brachytherapy sources from the end-user perspective

    Independent primary standards for brachytherapy photon-emitting source calibration in terms of dose-rate to water have been developed within the framework of the Euramet T2.J06 project. The introduction of dose-rate to water calibration presents an important change in clinical brachytherapy dosimetry that is expected to result to improved dosimetric accuracy. Nevertheless, as with any change in dosimetry for radiation therapy purposes, a phase-in period of well concerted actions aimed at precluding ambiguities and accidents at the end-user level is necessary. The overall uncertainty budget of clinical brachytherapy applications, as well as current trends in brachytherapy treatment planning system dose-calculation algorithms, also need to be considered for a realistic assessment of the net benefit of improving source calibration accuracy. (authors)

  8. Brachytherapy: Physical and clinical aspects

    take advantage of published results. The use of uniform models and methods in brachytherapy treatments simplifies comparison of treatment results. A typical treatment in which a model may be used is, for example, the treatment of cancer of the cervix, in which the dose is given to a specific point A, or low dose rate (LDR) treatments of head and neck cancers using 192Ir wires. In this latter case the Paris model provides suitable guidelines for calculation of the treatment dose and time. For treatments in which dose optimization techniques are used, the treatment times depend on how the sources are positioned relative to the dose calculation points and on the source strength. In situations in which the system to be used is not obvious, the scientific literature should be consulted in order to take full advantage of already existing experience. With the use of a specific method for the brachytherapy treatment and a model for the dose distribution calculation, comparison of results is simplified. The use of a well established dosimetric system for the treatment of cancer gives a common point for such comparisons. However, the use of a model alone is not sufficient to validate results; it is necessary to have a reliable method for determination of the source strength in order for the dose calculation to be accurate. This means that it is necessary for brachytherapy sources to be calibrated, with the calibration traceable to a national or international standards laboratory. The important aspects of any brachytherapy treatment are: Use of a suitable dosimetric model for the treatment time and dose calculation; Use of calibrated sources. These are by no means all the necessary components. A treatment does not reach its goals if the source misses its aimed positions by a large margin; that is, if there are severe geographical misses in placing the sources relative to their intended positions. Owing to the steep dose gradient that characterizes brachytherapy, such geometrical

  9. Studies on the development of 169Yb-brachytherapy seeds: New generation brachytherapy sources for the management of cancer

    This paper describes development of 169Yb-seeds by encapsulating 0.6–0.65 mm (ϕ) sized 169Yb2O3 microspheres in titanium capsules. Microspheres synthesized by a sol–gel route were characterized by XRD, SEM/EDS and ICP-AES. Optimization of neutron irradiation was accomplished and 169Yb-seeds up to 74 MBq of 169Yb could be produced from natural Yb2O3 microspheres, which have the potential for use in prostate brachytherapy. A protocol to prepare 169Yb-brachytherapy sources (2.96–3.7 TBq of 169Yb) with the use of enriched targets was also formulated

  10. Simulation of dose distribution for iridium-192 brachytherapy source type-H01 using MCNPX

    Dosimetric data for a brachytherapy source should be known before it used for clinical treatment. Iridium-192 source type H01 was manufactured by PRR-BATAN aimed to brachytherapy is not yet known its dosimetric data. Radial dose function and anisotropic dose distribution are some primary keys in brachytherapy source. Dose distribution for Iridium-192 source type H01 was obtained from the dose calculation formalism recommended in the AAPM TG-43U1 report using MCNPX 2.6.0 Monte Carlo simulation code. To know the effect of cavity on Iridium-192 type H01 caused by manufacturing process, also calculated on Iridium-192 type H01 if without cavity. The result of calculation of radial dose function and anisotropic dose distribution for Iridium-192 source type H01 were compared with another model of Iridium-192 source

  11. Simulation of dose distribution for iridium-192 brachytherapy source type-H01 using MCNPX

    Purwaningsih, Anik [Center for development of nuclear informatics, National Nuclear Energy Agency, PUSPIPTEK, Serpong, Banten 15310 (Indonesia)

    2014-09-30

    Dosimetric data for a brachytherapy source should be known before it used for clinical treatment. Iridium-192 source type H01 was manufactured by PRR-BATAN aimed to brachytherapy is not yet known its dosimetric data. Radial dose function and anisotropic dose distribution are some primary keys in brachytherapy source. Dose distribution for Iridium-192 source type H01 was obtained from the dose calculation formalism recommended in the AAPM TG-43U1 report using MCNPX 2.6.0 Monte Carlo simulation code. To know the effect of cavity on Iridium-192 type H01 caused by manufacturing process, also calculated on Iridium-192 type H01 if without cavity. The result of calculation of radial dose function and anisotropic dose distribution for Iridium-192 source type H01 were compared with another model of Iridium-192 source.

  12. Development of a well- type chamber for measurement of source activation in brachytherapy

    Objective: To develop a well-type chamber for measuring air kerma strength of source and improve accuracy for source activity. Methods: By drawing advanced experience from abroad and combining the condition of our country, the authors designed a plan, drew the blueprint, selected the material, processed and assembled the well- type chamber, and carried out a performance test. Result: The imported and self-made well- type chambers were measured in the same condition for comparison. The results should be that the long- term stability of the self-made well- type chamber is 0.4 %, and the technique index is 2%; the recombination rate of ionized charges is 0.9995% and the technique index is 1.000; the measurement accuracy of the well-type chamber is 0.02%, and the technique index is 0.5%. For the self-made well-type chamber, the flat response of peak sensitivity is fixed while for imported one the flat response changes around 0.1% within 5 mm of peak sensitivity. Conclusions: The strong points of the self-made well-type chamber are quick speed and accuracy in measurement and can measure for 192Ir, 125I and 103 Pd sources. Its measurement range is from 3. 7 MBq to 7. 4 x 105 MBq. The development of the well-type chamber fills the gaps of on -site measurement instruments and becomes a product with independent intellectual property right in our country. (authors)

  13. Source localisation and dose verification for a novel brachytherapy unit

    Metaxas, Marinos G.

    A recent development in the field of radiotherapy has been the introduction of the PRS Intrabeam system (Carl Zeiss Surgical GmbH, Oberkochen, Germany). This is essentially a portable, miniaturised, electron-driven photon generator that allows high intensity, soft-energy x-rays (50 kVp) to be delivered directly to the tumour site in a single fraction. The system has been used for the interstitial radiation treatment of both brain and breast tumours. At present, a standardised in-vivo dose verification technique is not available for the PRS treatments. The isotropical distribution of photons about the tip of the PRS probe inserted in the tissue can effectively be viewed as a point source of radiation buried in the body. This work has looked into ways of localising the PRS source utilising its own radiation field. Moreover, the response of monoenergetic sources, mimicking realistic brachytherapy sources, has also been investigated. The purpose of this project was to attempt to localise the source as well as derive important dosimetric information from the resulting image. A detection system comprised of a well-collimated Germanium detector (HPGe) has been devised in a rotate-translate Emission Computed Tomography (ECT) modality. The superior energy resolving ability of the detection system allowed for energy selective reconstruction to be carried out in the case of the monoenergetic source (241Am). Results showed that the monoenergetic source can be localised to within 1 mm and the continuous PRS x-ray source to within 3mm. For the PRS dose map derivation, Monte Carlo studies have been employed in order to extract information on the dosimetric aspect of the resulting image. The final goal of this work was therefore to formulate a direct mathematical relation (Transform Map) between the image created by the escaping photons and the dose map as predicted by the theoretical model. The formation therefore of the in-vivo PRS image could allow for a real-time monitoring

  14. Production of 125I seed sources for brachytherapy uses

    The production of radioactive sources of 125I, used mainly for the brachytherapy of prostate and ocular cancer, is a work that is being carried out in the plant of production of radioisotopes (PPR) of the Nuclear Center Racso of the IPEN. The employed methodology is based on the 125I physical-chemistry adsorption at silver wires coated with palladium. In the realization of the tests, it has been considered the procedure used by India and Iran participants of this CRP. In the execution of this work, the 131I radioisotope is been used simulating the 125I, because in the PPR-IPEN we produce the 131I. In total 50 samples were used, they were divided in ten groups. In first place with nine working groups, the optimum conditions for work for the coating of the silver wires with palladium were obtained, these being the following: simple method, employing PdCl2 0.1 m, pH of 5.5 to 6.5 and a temperature of 100 deg. C. Later on, a series of tests were carried out to determine the appropriate parameters for the adsorption of 131I in the previously treated wires, these being the following: carrier concentration of Ki 0.03 m, time of adsorption of 6 hours, and temperature of 70 deg. C. Finally, the percentage of 131I adsorption was obtained in the silver wires tried previously with palladium chloride solution of 98.24%. The control of leachability was made, having very good results. To confirm these previously mentioned parameters, a test was made with ten pieces of silver wires, corresponding to the group 10, giving the confirmation as a result of these. Also, samples of the titanium tube have been sent for test with microplasma welding to a French company: air welding liquidates export. With these results obtained, subsequently the production of these radioactive sources will be carried out employing 125I as a radioisotope. (author)

  15. Identification of 192Ir seeds in localization images using a novel statistical pattern recognition approach and a priori information

    Purpose / Objective: Manual labeling of individual 192Ir seeds in localization images for dosimetry of multi-strand low-dose-rate (LDR) implants is labor intensive, tedious and prone to error. The objective of this investigation is to develop computer-based methods that analyze digitized localization images, improve dosimetric efficiency, and reduce labeling errors. Materials and Methods: 192Ir localization films were digitized with a scanned-laser system and analyzed using Multiscale, Geometric, Statistical Pattern Recognition (MGSPR), a technique that recognizes and classifies pixels in gray-scale images based on their surrounding, neighborhood geometry. To 'teach' MGSPR how to recognize specific objects, a Gaussian-based mathematical filter set is applied to training images containing user-labeled examples of the desired objects. The filters capture a broad range of descriptive geometric information at multiple spatial scales. Principled mathematical analysis is used to determine the linear combination of filters from a large base set that yields the best discrimination between object types. Thus the sensitivity of the filters can be 'tuned' to detect specific objects such as192 Ir seeds. For a given pixel, the output of the filter is a multi-component feature vector that uniquely describes the pixel's geometric characteristics. Pixels with similar geometric attributes have feature vectors that naturally 'cluster', or group, in the multidimensional space called 'feature space'. After statistically quantifying the training-set clusters in feature space, pixels found in new images are automatically labeled by correlation with the nearest cluster, e.g., the cluster representing 192Ir seeds. One of the greatest challenges in statistical pattern recognition is to determine which filters result in the best labeling. Good discrimination is achieved when clusters are compact and well isolated from one another in feature space. The filters used in this study are unique

  16. Factors affecting radiation injury after interstitial brachytherapy for brain tumors

    The effects of brachytherapy on normal brain tissue are not easily delineated in the clinical setting because of the presence of concurrent radiation-induced changes in the coexistent brain tumor. Sequential morphologic studies performed after the implantation of radioactive sources into the brains of experimental animals have provided a better understanding of the character and magnitude of the structural changes produced by interstitial irradiation on normal brain tissue. Furthermore, the clinical experience accumulated thus far provides not only relevant information, but also some guidelines for future treatment policies. In this paper, the authors summarize the experimental findings and review the pathologic and clinical features of brain injury caused by interstitial brachytherapy. A number of studies in the older literature examined the effects of radioisotopes such as radium-226 (38--43), radon-22 (44--46), gold-198 (29,47--50), tantalum-182 (29,51,52) yttrium-9- (50,53,54), and cobalt-60 (29,50,55). This review is restricted to low- and high-activity encapsulated iodine-125 (125I) and iridium-192 (192Ir), the isotopes that are most commonly used in current clinical practice

  17. Attenuation measurements show that the presence of a TachoSil surgical patch will not compromise target irradiation in intra-operative electron radiation therapy or high-dose-rate brachytherapy

    Surgery of locally advanced and/or recurrent rectal cancer can be complemented with intra-operative electron radiation therapy (IOERT) to deliver a single dose of radiation directly to the unresectable margins, while sparing nearby sensitive organs/structures. Haemorrhages may occur and can affect the dose distribution, leading to an incorrect target irradiation. The TachoSil (TS) surgical patch, when activated, creates a fibrin clot at the surgical site to achieve haemostasis. The aim of this work was to determine the effect of TS on the dose distribution, and ascertain whether it could be used in combination with IOERT. This characterization was extended to include high dose rate (HDR) intraoperative brachytherapy, which is sometimes used at other institutions instead of IOERT. CT images of the TS patch were acquired for initial characterization. Dosimetric measurements were performed in a water tank phantom, using a conventional LINAC with a hard-docking system of cylindrical applicators. Percentage Depth Dose (PDD) curves were obtained, and measurements made at the depth of dose maximum for the three clinically used electron energies (6, 9 and 12MeV), first without any attenuator and then with the activated patch of TS completely covering the tip of the IOERT applicator. For HDR brachytherapy, a measurement setup was improvised using a solid water phantom and a Farmer ionization chamber. Our measurements show that the attenuation of a TachoSil patch is negligible, both for high energy electron beams (6 to 12MeV), and for a HDR 192Ir brachytherapy source. Our results cannot be extrapolated to lower beam energies such as 50 kVp X-rays, which are sometimes used for breast IORT. The TachoSil surgical patch can be used in IORT procedures using 6MeV electron energies or higher, or HDR 192Ir brachytherapy

  18. COMS eye plaque brachytherapy dosimetric sensitivity to source photon energy and seed design

    This study explores the influence of source photon energy on eye plaque brachytherapy dose distributions for a 16 mm COMS plaque filled with 103Pd, 125I, or 131Cs sources or monoenergetic photon emissions ranging from 12 keV to 100 keV. Dose distributions were similarly created for all permutations of three common brachytherapy seed designs. Within this range, sources with average energy ≤22 keV may reduce dose to the opposite eye wall by more than a factor of 2 while maintaining tolerable proximal sclera doses when prescribing to depths of 9 mm or less. Current commercially-available brachytherapy sources can exhibit up to 15% relative dosimetric sensitivity to seed design at regions within the eye. - Highlights: • Episcleral eye plaque brachytherapy utilizes low-energy photon-emitting sources. • Dose distribution sensitivity to source photon energy and seed design was examined. • Tumor dose conformity and critical structure sparing from ≤22 keV photons is preferred. • Ocular dose distributions varied by up to 15% with seed design permutations

  19. Metal stent and endoluminal high-dose rate 192iridium brachytherapy in palliative treatment of malignant biliary tract obstruction

    Since December 1989, 9 patients with inoperable malignant biliary tract obstruction were treated palliatively by a combined modality treatment consisting of placement of a permanent biliary endoprosthesis followed by intraluminal high dose-rate 192Ir brachytherapy. A dose of 10 Gy was delivered in a hyperfractionated schedule at the point of reference in a distance of 7.5 mm of centre of the source. External small field radiotherapy (50.4 Gy, 1.8 Gy per day, 5 fractions per week) was also given in six cases (M/O, Karnofsky >60%). In 9/9 cases an unrestrained bile flow and an interruption of pruritus was achieved, in 78% (7/9) of cases the duration of palliation was as long as the survival time (median survival time 7.5 months). (orig.)

  20. In-phantom dosimetric measurements as quality control for brachytherapy. System check and constancy check; Messungen im Festkoerperphantom als Qualitaetskontrolle in der Brachytherapie. Systempruefung und Konstanzpruefung

    Kollefrath, Michael; Bruggmoser, Gregor; Nanko, Norbert; Gainey, Mark [Universitaetsklinik Freiburg (Germany). Klinik fuer Strahlenheilkunde

    2015-09-01

    In brachytherapy dosimetric measurements are difficult due to the inherent dose-inhomogeneities. Typically in routine clinical practice only the nominal dose rate is determined for computer controlled afterloading systems. The region of interest lies close to the source when measuring the spatial dose distribution. In this region small errors in the positioning of the detector, and its finite size, lead to large measurement uncertainties that exacerbate the routine dosimetric control of the system in the clinic. The size of the measurement chamber, its energy dependence, and the directional dependence of the measurement apparatus are the factors which have a significant influence on dosimetry. Although ionisation chambers are relatively large, they are employed since similar chambers are commonly found on clinical brachytherapy units. The dose is determined using DIN 6800 [11] since DIN 6809-2 [12], which deals with dosimetry in brachytherapy, is antiquated and is currently in the process of revision. Further information regarding dosimetry for brachytherapy can be found in textbooks [1] and [2]. The measurements for this work were performed with a HDR (High-Dose-Rate) {sup 192}Ir source, type mHDR V2, and a Microselectron Afterloader V2 both from Nucletron/Elekta. In this work two dosimetric procedures are presented which, despite the aforemention difficulties, should assist in performing checks of the proper operation of the system. The first is a system check that measures the dose distribution along a line and is to be performed when first bringing the afterloader into operation, or after significant changes to the system. The other is a dosimetric constancy check, which with little effort can be performed monthly or weekly. It simultaneously verifies the positioning of the source at two positions, the functionality of the system clock and the automatic re-calculation of the source activity.

  1. Clinical Practice and Quality Assurance Challenges in Modern Brachytherapy Sources and Dosimetry

    Modern brachytherapy has led to effective treatments through the establishment of broadly applicable dosimetric thresholds for maximizing survival with minimal morbidity. Proper implementation of recent dosimetric consensus statements and quality assurance procedures is necessary to maintain the established level of safety and efficacy. This review classifies issues as either 'systematic' or 'stochastic' in terms of their impact on large groups or individual patients, respectively. Systematic changes affecting large numbers of patients occur infrequently and include changes in source dosimetric parameters, prescribing practice, dose calculation formalism, and improvements in calculation algorithms. The physicist must be aware of how incipient changes accord with previous experience. Stochastic issues involve procedures that are applied to each patient individually. Although ample guidance for quality assurance of brachytherapy sources exists, some ambiguities remain. The latest American Association of Physicists in Medicine guidance clarifies what is meant by independent assay, changes source sampling recommendations, particularly for sources in sterile strands and sterile preassembled needles, and modifies action level thresholds. The changing environment of brachytherapy has not changed the fact that the prime responsibility for quality assurance in brachytherapy lies with the institutional medical physicist

  2. Establishment of the RSS reentrant chamber as a reference standard for brachytherapy sources

    Re-entrant chambers provide a reliable, sensitive and easy method for calibrating the brachytherapy sources, at the hospital site. This work reports on the establishment of the RSS well chamber, as a reference chamber, for the routine calibration of the hospital well chambers

  3. Biological effect of Pulsed Dose Rate brachytherapy with stepping sources

    Purpose: To explore the possible increase of radiation effect in tissues irradiated by pulsed brachytherapy (PDR), for local tissue dose-rates between those 'averaged over the whole pulse' and the instantaneous high dose rates close to the dwell positions. An earlier publication (Fowler and Mount 1992) had shown that, for dose rates (averaged for the duration of the pulse) up to 3 Gy/h, little change of isoeffect doses from continuous low dose rate (CLDR) are expected, unless larger doses per fraction than 1 Gy are used, and especially if components of very rapid repair are present with half-times of less than about 0.5 hours. However, local and transient dose rates close to stepping sources can be up to several Gy per minute. Methods: Calculations were done assuming the linear quadratic formula for radiation damage, in which only the dose-squared term is subject to repair, at a constant exponential rate. The formula developed by Dale for fractionated low-dose-rate radiotherapy was used. A constant overall time of 140 hours and constant total dose of 70 Gy were assumed throughout, the continuous low dose-rate of 0.5 Gy/h (CLDR) providing the unitary standard effects for each PDR condition. Effects of dose-rates ranging from 4 Gy/h to 120 Gy/h (HDR at 2 Gy/min) were studied, and T (1(2)) from 4 minutes to 1.5 hours. Results: Curves are presented relating the ratio of increased biological effect (proportional to log cell kill) calculated for PDR relative to CLDR. Ratios as high as 1.5 can be found for large doses per pulse (> 1 Gy) at high instantaneous dose-rates if T (1(2)) in tissues is as short as a few minutes. The major influences on effect are dose per pulse, half-time of repair in the tissue, and - when T (1(2)) is short - the instantaneous dose-rate. Maximum ratios of PDR/CLDR effect occur when the dose-rate is such that pulse duration is approximately equal to T (1(2)) of repair. Results are presented for late-responding tissues, the differences from CLDR

  4. Establishment of Ge-doped optical fibres as thermoluminescence dosimeters for brachytherapy

    Issa, Fatma, E-mail: f.issa@surrey.ac.uk [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Department of Radiotherapy, Tripoli Medical Centre (TMC), Tripoli (Libya); Abdul Rahman, A.T. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); School of Physics and Material Studies, Faculty of Applied Sciences, Universiti Teknologi MARA Malaysia, Campus of Negeri Sembilan, 72000 Kuala Pilah (Malaysia); Hugtenburg, Richard P. [Department of Medical Physics and Clinical Engineering, Abertawe Bro Morgannwg UHB and School of Medicine, Swansea University, Swansea, SA2 8PP (United Kingdom); Bradley, David A. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Department of Radiological Sciences, King Saud University, P.O. Box 10219, Riyadh 11432 (Saudi Arabia); Nisbet, Andrew [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Department of Medical Physics, Royal Surrey County Hospital NHS Foundation Trust, Guildford, GU2 7XX (United Kingdom)

    2012-07-15

    This study aims to establish the sensitive, {approx}120 {mu}m high spatial resolution, high dynamic range Ge-doped optical fibres as thermoluminescence (TL) dosimeters for brachytherapy dose distribution. This requires investigation to accommodate sensitivity of detection, both for the possibility of short range dose deposition from beta components as well as gamma/x-mediated dose. In-air measurements are made at distances close to radionuclide sources, evaluating the fall off in dose along the transverse axis of {sup 133}Ba and {sup 60}Co radioactive sources, at distances from 2 mm up to 20 mm from their midpoints. Measurements have been compared with Monte Carlo code DOSRZnrc simulations for photon-mediated dose only, agreement being obtained to within 3% and 1% for the {sup 133}Ba and {sup 60}Co sources, respectively. As such, in both cases it is determined that as intended, beta dose has been filtered out by source encapsulation. - Highlights: Black-Right-Pointing-Pointer We seek to establish Ge-doped optical fibres as TLDs for brachytherapy. Black-Right-Pointing-Pointer Dose was evaluated along the central axis of {sup 133}Ba and {sup 60}Co, at 2 mm-20 mm. Black-Right-Pointing-Pointer We verify values using DOSRZnrc Monte Carlo code simulations. Black-Right-Pointing-Pointer Good agreement is between dose measurements and calculation to within 3% and 1%. Black-Right-Pointing-Pointer Methodology is to be used in obtaining doses around {sup 125}I and {sup 192}Ir sources.

  5. Measurement of disintegration rate and decay branching ratio for nuclide 192Ir with β-, EC mixing decays by using 4πβ-γ coincidence counting

    The absolute disintegration rates for nuclide 192Ir were measured with a 4πβ-γ (HPGe) coincidence apparatus by using parameter method and extrapolation method. The final uncertainties obtained were 0.4% and 0.5% respectively for a confidence level of 99.7%. The method with which both the disintegration rate and the decay branching ratio can be measured for nuclides with β- and EC mixing decays was proposed and described. The β- branching ratio in 192Ir decays was measured being 0.9572. The final uncertainties of disintegration rates and β- decay branching ratio with this method were 1.5% and 1.8% respectively

  6. Measurement of air kerma rate and absorbed dose for brachytherapy sources with secondary standard dosimeter

    The air kerma measurements for brachytherapy sources are generally recommended to be done at one meter using large volume chambers. These measurements pose problems due to low signal from brachytherapy sources. Non-availability of calibrated large volume chambers at a hospital adds to the problem of air kerma measurements. Therefore, the use of commonly available secondary standard dosimeter having 0.6 cc chambers has been examined. Correction factors to be applied at small source to chamber distances have been determined. Measurements from 137Cs source of nominal activity as low as 1.11 GBq (30 mCi) could be carried out using an integration time of about 20 minutes at minimum distance of 1.5 cm. For source to chamber distance beyond 5 cm, the correction factor approaches unity. (author)

  7. Measurement of anisotropic angular distributions of photon energy spectra for I-125 brachytherapy sources

    The angular distribution of photon energy spectra emitted from an I-125 brachytherapy source was measured using a specially designed jig in the range of ±70° in the plane of the long axis of the source. It is important to investigate the angular dependence of photon emissions from these sources for the calibration of the air kerma rate. The results show that the influence of the distributions between 0° and ±8° is small enough to allow a calibration using current primary instruments which have a large entrance window. - Highlights: ► Angular energy distribution for an I-125 brachytherapy source was measured. ► Variation of the distribution is sufficiently small. ► It is acceptable for primary calibration of the source strength. ► Distributions should be taken into consideration in some instruments.

  8. Dosimetric and clinical comparison between MammoSite and interstitial HDR brachytherapy in treatment of early stage breast cancer after conserving surgery

    Objective: To comparatively study dosimetric evaluation, side effects in early and late stage, and cosmetic outcome between MammoSite and interstitial using high-dose-rate (HDR) brachytherapy accelerated partial breast irradiation (APBI) in early stage breast cancer patient after conserving surgery. Methods: From January 2004 to December 2004, 10 breast cancer cases were treated with HDR 192Ir APBI after Lumpectomy surgery, 6 cases with interstitial brachytherapy, 4 cases with MammoSite. Sources were placed during the operation in all patients, distance from cavity to skin > 5-7 mm in interstitial brachytherapy group, one case is 6.5 mm, 3 cases > 10 mm in MammoSite group. Treatment Target area is 20 mm away from cavity in interstitial brachytherapy group with DHI 0.77, 10 mm away from Balloon margin in MammoSite with DHI 0.73. Results: Follow up 12-24 months while median follow-up was 18 months for the whole group (100%). During the treatment, grade III acute reactions were not seen in both group, grade I or II were seen including: erythema, edema, tenderness and infection. More late toxicity reaction including skin fibrosis, breast tenderness and fat necrosis were observed in interstitial brachytherapy group than that of MammoSite group. Cosmetic outcome evaluation were excellent in 12 months 100% (patient) and 83% (doctor) in interstitial brachytherapy, 100% in MammoSite group, respectively, none recurrence. Conclusions: Interstitial brachytherapy shows more uniformity in dose distribution as well as larger treatment volume, while MammoSite tends to be stable in repeatability and easy in use. Both groups show excellent cosmetic results, with same acute and late reactions. (authors)

  9. Deterministic calculations of radiation doses from brachytherapy seeds

    Brachytherapy is used for treating certain types of cancer by inserting radioactive sources into tumours. CDTN/CNEN is developing brachytherapy seeds to be used mainly in prostate cancer treatment. Dose calculations play a very significant role in the characterization of the developed seeds. The current state-of-the-art of computation dosimetry relies on Monte Carlo methods using, for instance, MCNP codes. However, deterministic calculations have some advantages, as, for example, short computer time to find solutions. This paper presents a software developed to calculate doses in a two-dimensional space surrounding the seed, using a deterministic algorithm. The analysed seeds consist of capsules similar to IMC6711 (OncoSeed), that are commercially available. The exposure rates and absorbed doses are computed using the Sievert integral and the Meisberger third order polynomial, respectively. The software also allows the isodose visualization at the surface plan. The user can choose between four different radionuclides (192Ir, 198Au, 137Cs and 60Co). He also have to enter as input data: the exposure rate constant; the source activity; the active length of the source; the number of segments in which the source will be divided; the total source length; the source diameter; and the actual and effective source thickness. The computed results were benchmarked against results from literature and developed software will be used to support the characterization process of the source that is being developed at CDTN. The software was implemented using Borland Delphi in Windows environment and is an alternative to Monte Carlo based codes. (author)

  10. In-phantom dosimetric measurements as quality control for brachytherapy. System check and constancy check

    In brachytherapy dosimetric measurements are difficult due to the inherent dose-inhomogeneities. Typically in routine clinical practice only the nominal dose rate is determined for computer controlled afterloading systems. The region of interest lies close to the source when measuring the spatial dose distribution. In this region small errors in the positioning of the detector, and its finite size, lead to large measurement uncertainties that exacerbate the routine dosimetric control of the system in the clinic. The size of the measurement chamber, its energy dependence, and the directional dependence of the measurement apparatus are the factors which have a significant influence on dosimetry. Although ionisation chambers are relatively large, they are employed since similar chambers are commonly found on clinical brachytherapy units. The dose is determined using DIN 6800 [11] since DIN 6809-2 [12], which deals with dosimetry in brachytherapy, is antiquated and is currently in the process of revision. Further information regarding dosimetry for brachytherapy can be found in textbooks [1] and [2]. The measurements for this work were performed with a HDR (High-Dose-Rate) 192Ir source, type mHDR V2, and a Microselectron Afterloader V2 both from Nucletron/Elekta. In this work two dosimetric procedures are presented which, despite the aforemention difficulties, should assist in performing checks of the proper operation of the system. The first is a system check that measures the dose distribution along a line and is to be performed when first bringing the afterloader into operation, or after significant changes to the system. The other is a dosimetric constancy check, which with little effort can be performed monthly or weekly. It simultaneously verifies the positioning of the source at two positions, the functionality of the system clock and the automatic re-calculation of the source activity.

  11. Brachytherapy optimal planning with application to intravascular radiation therapy

    Sadegh, Payman; Mourtada, Firas A.; Taylor, Russell H.; Anderson, James H.

    1999-01-01

    We have been studying brachytherapy planning with the objective of manimizing the maximum deviation of the delivered dose from prescribed dose bounds for treatment volumes. A general framework for optimal treatment planning is presented and the minmax optimization is formulated as a linear program....... Dose rate calculations are based on the sosimetry formulation of the American Association of Physicists in Medicine, Task Group 43. We apply the technique to optimal planning for intravascular brachytherapy of intimal hyperplasia using ultrasound data and 192Ir seeds. The planning includes...

  12. Monte Carlo simulation of dosimetric parameters for hybrid PdI source in brachytherapy

    According to dose calculation formula recommended by AAPM TG-43U1, dose rate constant of' Model 6711 125I brachytherapy source was calculated by Monte Carlo method. The calculation results were in good agreement with TG-43U1. Then, dose rate constant, radial dose function and anisotropy function of new hybrid PdI source were calculated by Monte Carlo method. Empiric equations were obtained for radial dose function. (authors)

  13. A brachytherapy model-based dose calculation algorithm -AMIGOBrachy

    performed using an HDR 192Ir source. (author)

  14. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NMIJ and the BIPM

    Kessler, C.; Kurosawa, T.; Mikamoto, T.

    2016-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Metrology Institute of Japan (AIST-NMIJ), Japan, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the Japan Radioisotope Association (JRIA) in April 2015. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NMIJ and the BIPM standards for reference air kerma rate, is 1.0036 with a combined standard uncertainty of 0.0054. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Monte Carlo Dosimetry of the 60Co BEBIG High Dose Rate for Brachytherapy.

    Luciana Tourinho Campos

    Full Text Available The use of high-dose-rate brachytherapy is currently a widespread practice worldwide. The most common isotope source is 192Ir, but 60Co is also becoming available for HDR. One of main advantages of 60Co compared to 192Ir is the economic and practical benefit because of its longer half-live, which is 5.27 years. Recently, Eckert & Ziegler BEBIG, Germany, introduced a new afterloading brachytherapy machine (MultiSource®; it has the option to use either the 60Co or 192Ir HDR source. The source for the Monte Carlo calculations is the new 60Co source (model Co0.A86, which is referred to as the new BEBIG 60Co HDR source and is a modified version of the 60Co source (model GK60M21, which is also from BEBIG.The purpose of this work is to obtain the dosimetry parameters in accordance with the AAPM TG-43U1 formalism with Monte Carlo calculations regarding the BEBIG 60Co high-dose-rate brachytherapy to investigate the required treatment-planning parameters. The geometric design and material details of the source was provided by the manufacturer and was used to define the Monte Carlo geometry. To validate the source geometry, a few dosimetry parameters had to be calculated according to the AAPM TG-43U1 formalism. The dosimetry studies included the calculation of the air kerma strength Sk, collision kerma in water along the transverse axis with an unbounded phantom, dose rate constant and radial dose function. The Monte Carlo code system that was used was EGSnrc with a new cavity code, which is a part of EGS++ that allows calculating the radial dose function around the source. The spectrum to simulate 60Co was composed of two photon energies, 1.17 and 1.33 MeV. Only the gamma part of the spectrum was used; the contribution of the electrons to the dose is negligible because of the full absorption by the stainless-steel wall around the metallic 60Co. The XCOM photon cross-section library was used in subsequent simulations, and the photoelectric effect, pair

  16. Novel high resolution 125I brachytherapy source dosimetry using Ge-doped optical fibres

    The steep dose gradients close to brachytherapy sources limit the ability to obtain accurate measurements of dose. Here we use a novel high spatial resolution dosimeter to measure dose around a 125I source and compare against simulations. Ge-doped optical fibres, used as thermoluminescent dosimeters, offer sub-mm spatial resolution, linear response from 10 cGy to >1 kGy and dose-rate independence. For a 125I brachytherapy seed in a PMMA phantom, doses were obtained for source-dosimeter separations from 0.1 cm up to several cm, supported by EGSnrc/DOSRZznrc Monte Carlo simulations and treatment planning system data. The measurements agree with simulations to within 2.3%±0.3% along the transverse and perpendicular axes and within 3.0%±0.5% for measurements investigating anisotropy in angular dose distribution. Measured and Veriseed™ brachytherapy treatment planning system (TPS) values agreed to within 2.7%±0.5%. Ge-doped optical fibre dosimeters allow detailed dose mapping around brachytherapy sources, not least in situations of high dose gradient. - Highlights: • We evaluate fall-off in dose for distances from an 125I source of 1 mm to 60 mm. • The TL of optical fibres accommodate high dose gradients and doses that reduce by a factor of 103 across the range of separations. • We verify measured values using DOSRZnrc Monte Carlo code simulations and the Variseed™ Treatment Planning System. • Measured radial and angular dose are obtained with ≤3% uncertainty

  17. CT-guided brachytherapy. A novel percutaneous technique for interstitial ablation of liver malignancies; CT-gesteuerte Brachytherapie. Eine neue perkutane Technik zur interstitiellen Ablation von Lebermetastasen

    Ricke, J.; Wust, P.; Stohlmann, A.; Beck, A.; Cho, C.H.; Pech, M.; Wieners, G.; Spors, B.; Werk, M.; Rosner, C.; Haenninen, E.L.; Felix, R. [Klinik fuer Strahlenheilkunde, Charite Virchow-Klinikum, Humboldt-Univ. zu Berlin (Germany)

    2004-05-01

    Purpose: to assess safety and efficacy of CT-guided brachytherapy of liver malignancies. Patients and methods: 21 patients with 21 liver malignancies (19 metastases, two primary liver tumors) were treated with interstitial CT-guided brachytherapy applying a {sup 192}Ir source. In all patients, the use of image-guided thermal tumor ablation such as by radiofrequency or laser-induced thermotherapy (LITT) was impeded either by tumor size {>=} 5 cm in seven, adjacent portal or hepatic vein in ten, or adjacent bile duct bifurcation in four patients. Dosimetry was performed using three-dimensional CT data sets acquired after CT-guided positioning of the brachytherapy catheters. Results: the mean tumor diameter was 4.6 cm (2.5-11 cm). The mean minimal tumor dose inside the tumor margin amounted to 17 Gy (12-20 Gy). The proportion of the liver parenchyma exposed to > 5 gy was 18% (5-39%) of total liver parenchyma minus tumor volume. Nausea and vomiting were observed in six patients after brachytherapy (28%). One patient demonstrated obstructive jaundice due to tumor edema after irradiation of a metastasis adjacent to the bile duct bifurcation. We commonly encountered asymptomatic increases of liver enzymes. Local control rates after 6 and 12 months were 87% and 70%, respectively. Conclusion: CT-guided brachytherapy is safe and effective. This technique displays broader indications compared to image-guided thermal ablation by radiofrequency or LITT with respect to tumor size or localization. (orig.) [German] Ziel: Analyse der Sicherheit und Effektivitaet CT-gesteuerter Brachytherapie zur Ablation von Lebermalignomen. Patienten und Methodik: 21 Patienten mit 21 Lebermalignomen (19 Metastasen, zwei primaere Lebermalignome) wurden mit perkutaner, CT-gesteuerter interstitieller Brachytherapie mit {sup 192}Ir behandelt. Alle Patienten wiesen Umstaende auf, die eine bildgefuehrte thermische Ablation mit Radiofrequenz oder laserinduzierter Thermotherapie (LITT) einschraenkten

  18. Synthesis and characterization of hydroxyapatite porous matrixes for application as radiation sources in brachytherapy

    Porous ceramic materials based on calcium phosphate compounds (CPC) have been studied aiming at different biomedical applications such as implants, drug delivery systems and radioactive sources for brachytherapy. Two kinds of hydroxyapatite (HAp) powders and their ceramic bodies were characterized by a combination of different techniques (X-rays diffraction and fluorescence, infrared spectrophotometry, BET method, thermal analysis, and scanning electron microscopy) to evaluate their physico-chemical and microstructural characteristics in terms of chemical composition, segregated phases, microstructure, porosity, and chemical and thermal stability. The results revealed that these systems presented potential for use as porous biodegradable radioactive sources able to be loaded with a wide range of radionuclides for cancer treatment by the brachytherapy technique. (author)

  19. Radiation-induced light in optical fibers and plastic scintillators: Application to brachytherapy dosimetry

    A small plastic scintillator bonded to an optical fiber has several characteristics that make it promising as a brachytherapy dosimeter. In these dosimeters, scintillation light represents signal, whereas Cerenkov and luminescence light from the optical fiber stem is noise that must be subtracted. The dosimeter accuracy can be improved by optically filtering part of the fiber stem light. Spectral measurements were performed to guide the choice of scintillator, fiber, and filter. Spectral signatures and total luminescence of three scintillators and five different silica optical fibers, excited by a 8 Ci 192Ir source, were measured. The total radiation-induced light from the various optical fibers differed by up to a factor of 5.6. The percentage of fiber-produced light due to luminescence varied between 15 and 79%. A fiber with weak emission was used in the dosimeter with BC408S, a scintillator with minimum emission wavelength of 400 nm. A 400-nm cutoff UV filter gave a factor of two increase in signal-to-noise. The dosimeter response was linear for dose rates varying by at least three orders of magnitude, representing source-to-probe distances of 0.2--10 cm. Measurement errors of the dosimeter compare favorably with other brachytherapy dosimeters

  20. A design of brachytherapy source calibration template for air kerma rate/activity measurement

    This simple template can be used for the purpose of calibration of brachytherapy source, if the department does not have the calibration-track stand. One can design this template in the hospital itself as per the requirement, availability and facility, and the expenses also will be less. It is fully made up of a very thin 0.75 mm thickness of paper cardboard and this is the speciality. Currently this template is being utilized for accurate and easy calibration purposes

  1. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for 252Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect.

  2. Metal stent and endoluminal high-dose rate [sup 192]iridium brachytherapy in palliative treatment of malignant biliary tract obstruction. First experiences. Metallgeflecht-Endoprothese und intraluminare High-dose-rate-[sup 192]Iridium-Brachytherapie zur palliativen Behandlung maligner Gallengangsobstruktionen. Erste Erfahrungen

    Pakisch, B.; Stuecklschweiger, G.; Poier, E.; Leitner, H.; Poschauko, J.; Hackl, A. (Universitaets-Klinik fuer Radiologie, Abt. fuer Strahlentherapie, Graz (Austria)); Klein, G.E.; Lammer, J.; Hausegger, K.A. (Universitaets-Klinik fuer Radiologie, Abt. fuer Spezielle Roentgendiagnostik und Digitale Bilddiagnostische Verfahren, Graz (Austria))

    1992-06-01

    Since December 1989, 9 patients with inoperable malignant biliary tract obstruction were treated palliatively by a combined modality treatment consisting of placement of a permanent biliary endoprosthesis followed by intraluminal high dose-rate [sup 192]Ir brachytherapy. A dose of 10 Gy was delivered in a hyperfractionated schedule at the point of reference in a distance of 7.5 mm of centre of the source. External small field radiotherapy (50.4 Gy, 1.8 Gy per day, 5 fractions per week) was also given in six cases (M/O, Karnofsky >60%). In 9/9 cases an unrestrained bile flow and an interruption of pruritus was achieved, in 78% (7/9) of cases the duration of palliation was as long as the survival time (median survival time 7.5 months). (orig.).

  3. Verification of I-125 brachytherapy source strength for use in radioactive seed localization procedures.

    Metyko, John; Erwin, William; Landsberger, Sheldon

    2016-06-01

    A general-purpose nuclear medicine dose calibrator was assessed as a potential replacement for a dedicated air-communicating well-type ionization chamber (brachytherapy source strength verification instrument) for (125)I seed source strength verification for radioactive seed localization, where less stringent accuracy tolerances may be acceptable. The accuracy, precision and reproducibility of the dose calibrator were measured and compared to regulatory requirements. The results of this work indicate that a dose calibrator can be used for (125)I seed source strength verification for radioactive seed localization. PMID:27015651

  4. An orthodontic device for retaining implanted radioactive sources during brachytherapy for cancer of the oral cavity

    An orthodontic retainer was devised to keeping implanted radioactive sources in position and improve the quality of life during brachytherapy for cancer of the oral cavity. The retainer was used in 3 patients with oral cancer, one with cancer of the hard palate, one with cancer of the soft palate, and one with cancer of the floor of mouth, during brachytherapy using 198Au grains and 137Cs needles. These patients could speak freely. One with cancer of the hard palate could drink water and ingest semi-liquid food during treatment instead of nasal tube feeding. The plaster dental model obtained while making the retainer proved to be useful for training radiation oncologists. (author)

  5. Clinical implementation of AAPM Task Group 32 recommendations on brachytherapy source strength specification

    Historically the strength of sealed brachytherapy sources has been described by many physical quantities, including true activity, apparent activity, and equivalent mass of radium. Recently, the AAPM Task Group 32 recommended that these quantities be replaced by a single quantity, air-kerma strength, with units of μGy m2 h-1. A set of equations has been developed for unambiguously converting source strength estimates and renormalizing published dose-rate tables, which assume traditional quantities and units, into forms consistent with air-kerma strength. For commonly used brachytherapy sources, multiplicative conversion factors for each source-strength formalism and set of units are given. To convert equivalent mass of radium to air-kerma strength requires a single multiplicative factor, 7.23 μGy m2 h-1/mgRaEq, applicable to all sources. Based upon a review of vendor source specification practices, the factors for converting source strength of 198Au, 103Pd, and 125I seeds from apparent mCi to air-kerma strength are 2.06, 1.29, and 1.27 μGy m2 h-1/mCi(apparent), respectively. These factors are independent of source geometry but depend on the nominal exposure rate constant value selected by the vendor. Conversion factors applicable to mass of radium or true activity depend upon both source geometry and radionuclide identity. Because many of these conversion factors depend upon vendor choices of physical constants and exposure rate constants, readers are cautioned to carefully review vendor source strength specification practices before adopting these values clinically. Finally, the relationships between the various source strength quantities and absorbed dose rate in the medium surrounding the source are elucidated

  6. Novel tools for stepping source brachytherapy treatment planning: Enhanced geometrical optimization and interactive inverse planning

    Dinkla, Anna M., E-mail: a.m.dinkla@amc.uva.nl; Laarse, Rob van der; Koedooder, Kees; Petra Kok, H.; Wieringen, Niek van; Pieters, Bradley R.; Bel, Arjan [Department of Radiation Oncology, Academic Medical Center Amsterdam, Meibergdreef 9, Amsterdam 1105 AZ (Netherlands)

    2015-01-15

    Purpose: Dose optimization for stepping source brachytherapy can nowadays be performed using automated inverse algorithms. Although much quicker than graphical optimization, an experienced treatment planner is required for both methods. With automated inverse algorithms, the procedure to achieve the desired dose distribution is often based on trial-and-error. Methods: A new approach for stepping source prostate brachytherapy treatment planning was developed as a quick and user-friendly alternative. This approach consists of the combined use of two novel tools: Enhanced geometrical optimization (EGO) and interactive inverse planning (IIP). EGO is an extended version of the common geometrical optimization method and is applied to create a dose distribution as homogeneous as possible. With the second tool, IIP, this dose distribution is tailored to a specific patient anatomy by interactively changing the highest and lowest dose on the contours. Results: The combined use of EGO–IIP was evaluated on 24 prostate cancer patients, by having an inexperienced user create treatment plans, compliant to clinical dose objectives. This user was able to create dose plans of 24 patients in an average time of 4.4 min/patient. An experienced treatment planner without extensive training in EGO–IIP also created 24 plans. The resulting dose-volume histogram parameters were comparable to the clinical plans and showed high conformance to clinical standards. Conclusions: Even for an inexperienced user, treatment planning with EGO–IIP for stepping source prostate brachytherapy is feasible as an alternative to current optimization algorithms, offering speed, simplicity for the user, and local control of the dose levels.

  7. Novel tools for stepping source brachytherapy treatment planning: Enhanced geometrical optimization and interactive inverse planning

    Purpose: Dose optimization for stepping source brachytherapy can nowadays be performed using automated inverse algorithms. Although much quicker than graphical optimization, an experienced treatment planner is required for both methods. With automated inverse algorithms, the procedure to achieve the desired dose distribution is often based on trial-and-error. Methods: A new approach for stepping source prostate brachytherapy treatment planning was developed as a quick and user-friendly alternative. This approach consists of the combined use of two novel tools: Enhanced geometrical optimization (EGO) and interactive inverse planning (IIP). EGO is an extended version of the common geometrical optimization method and is applied to create a dose distribution as homogeneous as possible. With the second tool, IIP, this dose distribution is tailored to a specific patient anatomy by interactively changing the highest and lowest dose on the contours. Results: The combined use of EGO–IIP was evaluated on 24 prostate cancer patients, by having an inexperienced user create treatment plans, compliant to clinical dose objectives. This user was able to create dose plans of 24 patients in an average time of 4.4 min/patient. An experienced treatment planner without extensive training in EGO–IIP also created 24 plans. The resulting dose-volume histogram parameters were comparable to the clinical plans and showed high conformance to clinical standards. Conclusions: Even for an inexperienced user, treatment planning with EGO–IIP for stepping source prostate brachytherapy is feasible as an alternative to current optimization algorithms, offering speed, simplicity for the user, and local control of the dose levels

  8. Dose effect of guidewire position in intravascular brachytherapy

    It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for the 90Sr (NOVOSTE), 32P (Guidant) and 192Ir (BEST Ind.) sources with and without a guidewire in place. Guidewires were placed at various distances from the central axes of the sources. Due to the attenuation by the guidewires, a dose reduction of up to 70% behind a guidewire was observed for the beta sources, while the dose perturbation was found to be negligible for the gamma source. The dose reduction for the beta sources was found to be dependent on the guidewire location. For example, the dose reduction was 10% higher for a stainless steel guidewire located at 0.5 mm than that for the guidewire at 2 mm from the central axis of the source. The portion of the target volume affected (shadowed) dosimetrically by the guidewire was reduced when the guidewire was positioned farther away from the source. The shadow volume (in which the dose reduction occurs) can be reduced by up to 45% as the guidewire is moved away from the source axis from 0.5 mm to 2 mm. The dosimetric perturbations due to the presence of a metallic guidewire as well as their dependence on guidewire location should be considered in designing a new IVBT delivery device, in analysing the treatment efficacy, and/or in dose prescription for a beta source. (author)

  9. Assessment of the risks associated with Iodine-125 handling production sources for brachytherapy

    Souza, Daiane C.B.; Rostelato, Maria Elisa C.; Vicente, Roberto; Zeituni, Carlos A.; Tiezzi, Rodrigo; Costa, Osvaldo L.; Souza, Carla D.; Peleias Junior, Fernando S.; Rodrigues, Bruna T.; Souza, Anderson S.; Batista, Talita Q.; Melo, Emerson R.; Camargo, Anderson R., E-mail: dcsouza@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Karam Junior, Dib, E-mail: dib.karam@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil)

    2015-07-01

    In Brazil, prostate cancer is the second most frequent disease, with an estimated 68,800 new cases in 2013. This type of cancer can be treated with brachytherapy, which uses sealed sources of Iodine-125 implanted permanently in the prostate. These sources are currently imported at a high cost, making public treatment in large scale impractical. To reduce costs and to meet domestic demand, the laboratory for production of brachytherapy sources at the Nuclear and Energy Research Institute (IPEN) is currently nationalizing the production of this radioisotope. Iodine is quite volatile making the handling of its radioactive isotopes potentially dangerous. The aim of this paper is to evaluate the risks to which workers are exposed during the production and handling of the sources. The research method consisted initially of a literature review on the toxicity of iodine, intake limits, related physical risks, handling of accidents, generation of radioactive wastes, etc. The results allowed for establishing safety and radioprotection policies in order to ensure efficient and safe production in all stages and the implementation of good laboratory practices. (author)

  10. A simplified analytical dose calculation algorithm accounting for tissue heterogeneity for low-energy brachytherapy sources.

    Mashouf, Shahram; Lechtman, Eli; Beaulieu, Luc; Verhaegen, Frank; Keller, Brian M; Ravi, Ananth; Pignol, Jean-Philippe

    2013-09-21

    The American Association of Physicists in Medicine Task Group No. 43 (AAPM TG-43) formalism is the standard for seeds brachytherapy dose calculation. But for breast seed implants, Monte Carlo simulations reveal large errors due to tissue heterogeneity. Since TG-43 includes several factors to account for source geometry, anisotropy and strength, we propose an additional correction factor, called the inhomogeneity correction factor (ICF), accounting for tissue heterogeneity for Pd-103 brachytherapy. This correction factor is calculated as a function of the media linear attenuation coefficient and mass energy absorption coefficient, and it is independent of the source internal structure. Ultimately the dose in heterogeneous media can be calculated as a product of dose in water as calculated by TG-43 protocol times the ICF. To validate the ICF methodology, dose absorbed in spherical phantoms with large tissue heterogeneities was compared using the TG-43 formalism corrected for heterogeneity versus Monte Carlo simulations. The agreement between Monte Carlo simulations and the ICF method remained within 5% in soft tissues up to several centimeters from a Pd-103 source. Compared to Monte Carlo, the ICF methods can easily be integrated into a clinical treatment planning system and it does not require the detailed internal structure of the source or the photon phase-space. PMID:23965939

  11. Assessment of the risks associated with Iodine-125 handling production sources for brachytherapy

    In Brazil, prostate cancer is the second most frequent disease, with an estimated 68,800 new cases in 2013. This type of cancer can be treated with brachytherapy, which uses sealed sources of Iodine-125 implanted permanently in the prostate. These sources are currently imported at a high cost, making public treatment in large scale impractical. To reduce costs and to meet domestic demand, the laboratory for production of brachytherapy sources at the Nuclear and Energy Research Institute (IPEN) is currently nationalizing the production of this radioisotope. Iodine is quite volatile making the handling of its radioactive isotopes potentially dangerous. The aim of this paper is to evaluate the risks to which workers are exposed during the production and handling of the sources. The research method consisted initially of a literature review on the toxicity of iodine, intake limits, related physical risks, handling of accidents, generation of radioactive wastes, etc. The results allowed for establishing safety and radioprotection policies in order to ensure efficient and safe production in all stages and the implementation of good laboratory practices. (author)

  12. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement

    Ghassoun, J. [EPRA, Department of Physics, Faculty of Sciences Semlalia, PO Box: 2390, 40000 Marrakech (Morocco)], E-mail: ghassoun@ucam.ac.ma; Mostacci, D.; Molinari, V. [Laboratorio di Ingegneria Nucleare di Montecuccolino, via dei Colli 16, 40136 Bologna (Italy); Jehouani, A. [EPRA, Department of Physics, Faculty of Sciences Semlalia, PO Box: 2390, 40000 Marrakech (Morocco)

    2010-02-15

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for {sup 252}Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect.

  13. Effect of tissue inhomogeneities on dose distributions from Cf-252 brachytherapy source.

    Ghassoun, J

    2013-01-01

    The Monte Carlo method was used to determine the effect of tissue inhomogeneities on dose distribution from a Cf-252 brachytherapy source. Neutron and gamma-ray fluences, energy spectra and dose rate distributions were determined in both homogenous and inhomogeneous phantoms. Simulations were performed using the MCNP5 code. Obtained results were compared with experimentally measured values published in literature. Results showed a significant change in neutron dose rate distributions in presence of heterogeneities. However, their effect on gamma rays dose distribution is minimal. PMID:23069196

  14. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement.

    Ghassoun, J; Mostacci, D; Molinari, V; Jehouani, A

    2010-02-01

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for (252)Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect. PMID:19889549

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

    Malin, Martha J.

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

  16. The collapsed cone algorithm for 192Ir dosimetry using phantom-size adaptive multiple-scatter point kernels

    The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter.A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra.Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions.The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient

  17. Dosimetric characterization of a brachytherapy source for gynaecological applications

    In this work Monte Carlo calculations and experimental measurements of dose rate in water per unit air-kerma strength, D/Sk, of a low dose rate Amersham CDCS.J 137Cs source are reported. The Monte Carlo calculations included a detailed simulation of the geometric structure of the source embedded in a water medium. The experimental procedure included the construction of a lucite phantom with the same geometric characteristics as the one used in the simulation. Dose measurements were performed using high spatial resolution RadioChromic dye film and TL dosemeters for short and large distances from the source, respectively. The comparison between simulated and reported values in the literature of D/Sk for the same source are of 1.0% in average [1]. The differences between the TL measurements and the simulation also are of 1% in average, while the difference between the MC and the RadioChromic film are larger, particularly when the RadioChromic film received doses smaller than 7 Gy

  18. TG-43 U1 based dosimetric characterization of model 67-6520 Cs-137 brachytherapy source

    Purpose: Brachytherapy treatment has been a cornerstone for management of various cancer sites, particularly for the treatment of gynecological malignancies. In low dose rate brachytherapy treatments, 137Cs sources have been used for several decades. A new 137Cs source design has been introduced (model 67-6520, source B3-561) by Isotope Products Laboratories (IPL) for clinical application. The goal of the present work is to implement the TG-43 U1 protocol in the characterization of the aforementioned 137Cs source. Methods: The dosimetric characteristics of the IPL 137Cs source are measured using LiF thermoluminescent dosimeters in a Solid Water phantom material and calculated using Monte Carlo simulations with the GEANT4 code in Solid Water and liquid water. The dose rate constant, radial dose function, and two-dimensional anisotropy function of this source model were obtained following the TG-43 U1 recommendations. In addition, the primary and scatter dose separation (PSS) formalism that could be used in convolution/superposition methods to calculate dose distributions around brachytherapy sources in heterogeneous media was studied. Results: The measured and calculated dose rate constants of the IPL 137Cs source in Solid Water were found to be 0.930(±7.3%) and 0.928(±2.6%) cGy h-1 U-1, respectively. The agreement between these two methods was within our experimental uncertainties. The Monte Carlo calculated value in liquid water of the dose rate constant was Λ=0.948(±2.6%) cGy h-1 U-1. Similarly, the agreement between measured and calculated radial dose functions and the anisotropy functions was found to be within ±5%. In addition, the tabulated data that are required to characterize the source using the PSS formalism were derived. Conclusions: In this article the complete dosimetry of the newly designed 137Cs IPL source following the AAPM TG-43 U1 dosimetric protocol and the PSS formalism is provided.

  19. Development of high-activity 252Cf sources for neutron brachytherapy

    The Gershenson Radiation Oncology Center of Wayne State University (WSU), Detroit, Michigan, is using 252Cf medical sources for neutron brachytherapy. These sources are based on a 20-year-old design containing ≤ 30 microg 252Cf in the form of a cermet wire of Cf2O3 in a palladium matrix. The Radiochemical Engineering Development Center (REDC) of Oak Ridge National Laboratory has been asked to develop tiny high-activity 252Cf neutron sources for use with remote afterloading equipment to reduce treatment times and dose to clinical personnel and to expedite treatment of brain and other tumors. To date, the REDC has demonstrated that 252Cf loadings can be greatly increased in cermet wires much smaller than before. Equipment designed for hot cell fabrication of these wires is being tested. A parallel program is under way to relicense the existing source design for fabrication at the REDC

  20. Development of automated measurement system for radioactive intensities of sealed small radiation sources (iodine-125 seed source) for brachytherapy

    We have developed full automated measurement system for radioactive intensities of sealed small radiation sources (iodine-125 seed source) for brachytherapy in this work. Today, quality assurance (QA) of I-125 seed radioactive sources for brachytherapy following AAPM (American Association of Physicists in Medicine) Society's guideline is one of important subjects for hospitals that operate on patients for prostate cancer and medical companies that manufacture and sell these radioactive sources. In order to survey defective seed products into all the number of I-125 seed sources (there are usually fifteen seeds, one seed of dimensions is 0.8 mm φ × 4.5 mm length) within a cartridge, we have applied the method of single slit collimator with moving a radiation detector to measure each radioactive intensity of these I-125 seeds. As a result, it was found that our developed system in the present work has good performance of surveying the defective products manufactured with radioactive intensities out of about ±15% error (p < 0.05). (author)

  1. Standardization of iridium-192 coiled source in terms of air kerma output

    ICRU (1985) recommended that the output of gamma ray brachytherapy sources should be specified in terms of reference air kerma rate, defined as the kerma rate to air in air at a reference distance of 1 meter, perpendicular to the long axis of the source, corrected for air attenuation and scattering. As these measurements are difficult to carry out in the routine clinical use, it is the common practice to calibrate the re-entrant ionization chamber with respect to open air measurements and use the re-entrant chamber for routine measurements. This paper reports on the measurements carried out to correlate the nominal activity and air kerma rate of 192Ir wire sources supplied by the Board of Radiation and Isotope Technology, Department of Atomic Energy. (author). 3 refs, 1 tab

  2. Calculated neutron air kerma strength conversion factors for a generically encapsulated Cf-252 brachytherapy source

    Rivard, M J; D'Errico, F; Tsai, J S; Ulin, K; Engler, M J

    2002-01-01

    The sup 2 sup 5 sup 2 Cf neutron air kerma strength conversion factor (S sub K sub N /m sub C sub f) is a parameter needed to convert the radionuclide mass (mu g) provided by Oak Ridge National Laboratory into neutron air kerma strength required by modern clinical brachytherapy dosimetry formalisms indicated by Task Group No. 43 of the American Association of Physicists in Medicine (AAPM). The impact of currently used or proposed encapsulating materials for sup 2 sup 5 sup 2 Cf brachytherapy sources (Pt/Ir-10%, 316L stainless steel, nitinol, and Zircaloy-2) on S sub K sub N /m sub C sub f was calculated and results were fit to linear equations. Only for substantial encapsulation thicknesses, did S sub K sub N /m sub C sub f decrease, while the impact of source encapsulation composition is increasingly negligible as Z increases. These findings are explained on the basis of the non-relativistic kinematics governing the majority of sup 2 sup 5 sup 2 Cf neutron interactions. Neutron kerma and energy spectra resul...

  3. Standardization of the calibration of brachytherapy sources at the IAEA dosimetry laboratory

    A new service to SSDLs has been initiated at the IAEA Dosimetry Laboratory for providing calibrations of well-type ionisation chambers, used in brachytherapy applications, which are traceable to the International Measurement System. Considering that the most common radionuclide used in the developing countries is 137Cs, two such sources of the type used for gynaecological intracavitary applications have been purchased by the Agency and calibrated at the National Institute of Standards and Technology (NIST), USA. These 137Cs reference sources together with a well-type ionization chamber constitute the IAEA brachytherapy dosimetry standard. Based on the recommendations by a group of experts, a method has been developed for transferring calibrations to SSDLs which is described in this paper. The method is based on the acquisition by the SSDLs of sources and equipment similar to those at the IAEA. The well-type chamber is to be calibrated at the IAEA Dosimetry Laboratory, and this will be used at the SSDL to calibrate its own reference sources. These sources can in turn by used to calibrate well-type chambers from hospital users and to calibrate other type of sources by performing measurements in air. In order to standardize the procedures for the two methods and to provide guidance to the SSDLs, measurements have been carried out at the IAEA Dosimetry Laboratory. The reproducibility of the two type of measurements has been found to be better than 0.5%, and the uncertainty of calibrations estimated to be less than 1.5% (one standard deviation). (author). 8 refs, 8 figs, 2 tabs

  4. A Monte Carlo study on tissue dose enhancement in brachytherapy: a comparison between gadolinium and gold nanoparticles

    The aim of this study was to quantify the dose enhancement by gadolinium and gold nanoparticles in brachytherapy. MCNPX Monte Carlo code was used to simulate four brachytherapy sources: 60Co, 198Au, 192Ir, 169Yb. To verify the accuracy of our simulations, the obtained values of dose rate constants and radial dose functions were compared with corresponding published values for these sources. To study dose enhancements, a spherical soft tissue phantom with 15 cm in radius was simulated. Gadolinium and gold nanoparticles at 10, 20 and 30 mg/ml concentrations were separately assumed in a 1 × 1 × 1 cm3 volume simulating tumour. The simulated dose to the tumour with the impurity was compared to the dose without impurity, as a function of radial distance and concentration of the impurity, to determine the enhancement of dose due to the presence of the impurity. Dose enhancements in the tumour obtained in the presence of gadolinium and gold nanoparticles with concentration of 30 mg/ml, were found to be in the range of −0.5–106.1 and 0.4–153.1 % respectively. In addition, at higher radial distances from the source center, higher dose enhancements were observed. GdNPs can be used as a high atomic number material to enhance dose in tumour volume with dose enhancements up to 106.1 % when used in brachytherapy. Regardless considering the clinical limitations of the here-in presented model, for a similar source and concentration of nanoparticles, gold nanoparticles show higher dose enhancement than gadolinium nanoparticles and can have more clinical usefulness as dose enhancer material.

  5. Comparison between methods for fixing radioactive iodine in silver substrate for manufacturing brachytherapy sources

    Among the different ways to treat prostate cancer, brachytherapy with iodine- 125 seeds is an option that provides good results and fewer side effects. In the present study several deposition methods of radioactive iodine in a silver substrate were compared in order to choose the most suitable alternative for the routine production to be implemented at IPEN's laboratory. The methodology used was chosen based on the available infrastructure and experience of the researchers present. Therefore, the 131I was used for testing (same chemical behavior as 131I). Four methods were selected: Method 1 (test based on electrodeposition method developed by D.Kubiatowicz) presented 65.16% efficiency; Method 2 (chemical reaction based on the method developed by D. Kubiatowicz - HCl) with the result of 70.80% efficiency; method 3 (chemical reaction based on the method developed by Dr. Maria Elisa Rostelato) with 55.80% efficiency; Method 4 (IQ-IPEN) resulted in 99% efficiency. Since this method has more radioactive material fixation (which represents virtually the entire cost of the seed), the final price is the cheapest. This method is the suggested one to be implemented in the IPEN's laboratory for brachytherapy sources production. Besides, the method is the fasted one. (author)

  6. Absolute activity measurement of the electron-capture-based radionuclides 139Ce, 125I, 192Ir and 65Zn by liquid scintillation coincidence counting

    Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidence extrapolation technique. 125I, 192Ir and 65Zn were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The 139Ce measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since 139Ce decays purely by electron-capture, the basic method is described for this radionuclide. Results and difficulties encountered are discussed and uncertainty budgets are presented

  7. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources

    The Cf-252 is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research. Commercially its offer sources of different sizes, compact and with a fast neutrons emission of the order of 106 n/s-μg and an energy spectra that presents respectively maxim and average energy in 2.1 MeV and 0.7 MeV. In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf-252 will be used with the interstitial brachytherapy technique of high and low dose rate. In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV. These differences can produce maximum variations of the neutron kerma coefficients ratio for En > 1 keV of the one: 15% tumor/ICRU guest healthy tissue, 12% ICRU tumor/muscle, 12% ICRU healthy tissues ICRU/ICRU muscle, 22% substitutes tissue/tumor and 22% ICRU substitutes tissue/muscle. Also, it was found that the average value of the neutrons kerma coefficient for the 4 wicked tumors is from 6% to 7% smaller that the average value for the soft tissue in the interval energy of interest for therapy with fast neutrons with En > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of 252Cf, to optimize and to individualize the patients treatments. (Author)

  8. Investigations into the Optimization of Multi-Source Strength Brachytherapy Treatment Procedures

    Henderson, D L; Yoo, S

    2002-01-01

    The goal of this project is to investigate the use of multi-strength and multi-specie radioactive sources in permanent prostate implant brachytherapy. In order to fulfill the requirement for an optimal dose distribution, the prescribed dose should be delivered to the target in a nearly uniform dose distribution while simultaneously sparing sensitive structures. The treatment plan should use a small number of needles and sources while satisfying the treatment requirements. The hypothesis for the use of multi-strength and/or multi-specie sources is that a better treatment plan using fewer sources and needles could be obtained than by treatment plans using single-strength sources could reduce the overall number of sources used for treatment. We employ a recently developed greedy algorithm based on the adjoint concept as the optimization search engine. The algorithm utilizes and ''adjoint ratio'', which provides a means of ranking source positions, as the pseudo-objective function. It ha s been shown that the gre...

  9. Harmony search optimization for HDR prostate brachytherapy

    Panchal, Aditya

    In high dose-rate (HDR) prostate brachytherapy, multiple catheters are inserted interstitially into the target volume. The process of treating the prostate involves calculating and determining the best dose distribution to the target and organs-at-risk by means of optimizing the time that the radioactive source dwells at specified positions within the catheters. It is the goal of this work to investigate the use of a new optimization algorithm, known as Harmony Search, in order to optimize dwell times for HDR prostate brachytherapy. The new algorithm was tested on 9 different patients and also compared with the genetic algorithm. Simulations were performed to determine the optimal value of the Harmony Search parameters. Finally, multithreading of the simulation was examined to determine potential benefits. First, a simulation environment was created using the Python programming language and the wxPython graphical interface toolkit, which was necessary to run repeated optimizations. DICOM RT data from Varian BrachyVision was parsed and used to obtain patient anatomy and HDR catheter information. Once the structures were indexed, the volume of each structure was determined and compared to the original volume calculated in BrachyVision for validation. Dose was calculated using the AAPM TG-43 point source model of the GammaMed 192Ir HDR source and was validated against Varian BrachyVision. A DVH-based objective function was created and used for the optimization simulation. Harmony Search and the genetic algorithm were implemented as optimization algorithms for the simulation and were compared against each other. The optimal values for Harmony Search parameters (Harmony Memory Size [HMS], Harmony Memory Considering Rate [HMCR], and Pitch Adjusting Rate [PAR]) were also determined. Lastly, the simulation was modified to use multiple threads of execution in order to achieve faster computational times. Experimental results show that the volume calculation that was

  10. RADIOLOGICAL CRITERIA FOR PATIENT RELEASE FROM CLINIC AFTER RADIONUCLIDE THERAPY OF BRACHYTHERAPY WITH SEALED SOURCE IMPLANTATION

    M. I. M.I. Balonov

    2016-03-01

    Full Text Available Dose criteria for limitation of exposure incurred by persons helping the patients or living with patients discharged from hospitals following radionuclide therapy or brachytherapy with implanted sealed radionuclide sources have been proposed for national Russian regulation. By means of a conservative dosimetry model, the values of operational radiological criteria for patient discharge from hospital are substantiated, i.e. whole body activity for radionuclides 125I,131I,153Sm and 188Re as well as dose rate near patient body. Observance of suggested criteria included in the new Russian Standards for Radiation Safety (RSS-99/2009 will ensure radiation safety of people in near environment (family, close friends et ah.

  11. Effect of tissue Inhomogeneities on dose distributions from Cf-252 brachytherapy source

    The Monte Carlo method was used to determine the effect of tissue inhomogeneities on dose distribution from a Cf-252 brachytherapy source. Neutron and gamma-ray fluences, energy spectra and dose rate distributions were determined in both homogenous and inhomogeneous phantoms. Simulations were performed using the MCNP5 code. Obtained results were compared with experimentally measured values published in literature. Results showed a significant change in neutron dose rate distributions in presence of heterogeneities. However, their effect on gamma rays dose distribution is minimal. - Highlights: ► The effect of tissue inhomogeneities on dose distribution has been investigated. ► A comparison of our results with experimental data available in the literature is presented. ► Obtained results showed a significant change in neutron dose rate distributions.

  12. A statistical approach to infer the minimum setup distance of a well chamber to the wall or to the floor for 192Ir HDR calibration

    We propose a new method based on statistical analysis technique to determine the minimum setup distance of a well chamber used in the calibration of 192Ir high dose rate (HDR). The chamber should be placed at least this distance away from any wall or from the floor in order to mitigate the effect of scatter. Three different chambers were included in this study, namely, Sun Nuclear Corporation, Nucletron, and Standard Imaging. The results from this study indicated that the minimum setup distance varies depending on the particular chamber and the room architecture in which the chamber was used. Our result differs from that of a previous study by Podgorsak et al. [Med. Phys. 19, 1311-1314 (1992)], in which 25 cm was suggested, and also differs from that of the International Atomic Energy Agency (IAEA)-TECDOC-1079 report, which suggested 30 cm. The new method proposed in this study may be considered as an alternative approach to determine the minimum setup distance of a well-type chamber used in the calibration of 192Ir HDR

  13. Comparison between methods for fixing radioactive iodine in silver substrate for manufacturing brachytherapy sources

    Cancer is a term used generically to represent a group of more than 100 illnesses, including malignant tumors from different locations. According to World Health Organization (WHO), is a leading cause of death worldwide, accounted for 7.6 million deaths. Prostate cancer is the sixth most common type in the world, representing about 10% of all cases of cancer and its treatment may be by surgery, radiotherapy or even vigilant observation. A method of radiotherapy which has been extensively used in the early and intermediate stages of the illness is brachytherapy, where radioactive seeds are placed inside or next to the area requiring treatment, which reduces the probability of unnecessary damage to surrounding healthy tissues. Currently, the radioactive isotope Iodine-125, adsorbed on silver substrate, is one of the most used in prostate brachytherapy. The present study compares several deposition methods of radioactive Iodine on silver substrate, in order to choose the most suitable one to be implemented at the laboratory of radioactive sources production of IPEN. The methodology used was chosen based on the available infrastructure and experience of the researchers of the institute. Therefore, Iodine-131 was used for testing (same chemical behavior of Iodine -125). Three methods were selected: method 1 (test based on electrodeposition method, developed by David Kubiatowicz) which presented efficiency of 65.16% ; method 2 (chemical reaction based on the method developed by David Kubiatowicz -HCl) which presented efficiency of 70.80%; method 3 (chemical reaction based on the method developed by Dr. Maria Elisa Rostelato) which presented efficiency of 55.80% . Based on the results, the second method is the suggested one to be implemented at the laboratory of radioactive sources production of IPEN. (author)

  14. Monte Carlo modeling of 60 Co HDR brachytherapy source in water and in different solid water phantom materials

    Sahoo S

    2010-01-01

    Full Text Available The reference medium for brachytherapy dose measurements is water. Accuracy of dose measurements of brachytherapy sources is critically dependent on precise measurement of the source-detector distance. A solid phantom can be precisely machined and hence source-detector distances can be accurately determined. In the present study, four different solid phantom materials such as polymethylmethacrylate (PMMA, polystyrene, Solid Water, and RW1 are modeled using the Monte Carlo methods to investigate the influence of phantom material on dose rate distributions of the new model of BEBIG 60 Co brachytherapy source. The calculated dose rate constant is 1.086 ± 0.06% cGy h−1 U−1 for water, PMMA, polystyrene, Solid Water, and RW1. The investigation suggests that the phantom materials RW1 and Solid Water represent water-equivalent up to 20 cm from the source. PMMA and polystyrene are water-equivalent up to 10 cm and 15 cm from the source, respectively, as the differences in the dose data obtained in these phantom materials are not significantly different from the corresponding data obtained in liquid water phantom. At a radial distance of 20 cm from the source, polystyrene overestimates the dose by 3% and PMMA underestimates it by about 8% when compared to the corresponding data obtained in water phantom.

  15. 5-Year results of pulsed dose rate brachytherapy applied as a boost after breast-conserving therapy in patients at high risk for local recurrence from breast cancer

    Purpose: The aim of this study was to evaluate effect, toxicity, and cosmesis of a prospectively applied pulsed dose rate (PDR) brachytherapy boost schedule in patients with stage I/II/IIIa invasive breast cancer. Patients and Methods: A total of 113 patients were treated after breast-conserving surgery (BCS) and external beam radiotherapy (median 50 Gy, range 46-52). The boost dose was graded in accordance to the pathologic tumor characteristics: 20-25 Gy: incomplete resection (n=34), vascular invasion (n=27), close margin resection (n=41); 15 Gy: T2G3 stage (n=11). PDR brachytherapy (37 GBq, 192Ir source) was carried out after geometric volume optimization with 1 Gy/pulse/h. The implantation and dose specification were performed similar to the rules of the Paris system. Results: The overall local failure rate after a median follow-up of 61 months was 4.4% (5/113). The actuarial 5- and 8-year local recurrence-free survival rates were 95% and 93%, respectively. Cosmesis was rate by 90% of the patients as excellent or good. 14/113 patients experienced grade III (all caused by planar telangiectasia) and none of the patients grade IV late toxicity of the skin (RTOG/EORTC). A boost dose of 25 Gy resulted in a significantly higher rate of late toxicity (Fisher's exact test, p<0.01). Conclusions: PDR brachytherapy is safe, effective, and provides good cosmesis. A CLDR breast boost can be replaced by PDR brachytherapy without significant loss of therapeutic ratio. (orig.)

  16. The Role of Dosimetry Audits in Radiotherapy Quality Assurance: Eight Years of Experience in Greek External Beam Radiotherapy and Brachytherapy Centres

    The Greek Atomic Energy Commission (GAEC) runs dosimetry audits through on-site visits for photon and electron beams and for 192Ir brachytherapy high dose rate systems in all Greek radiotherapy centres. In audits, absolute and relative dosimetry measurements are being performed. The deviation, expressed as the percentage difference of the measured values by the GAEC to the respective stated values by the radiotherapy centre of absorbed dose to water or air kerma strength were recorded and compared to the action levels of ±3% (preventive actions needed) and ±5% (immediate corrective actions needed). The results of the subsequent audit rounds, each one lasting for approximately four years, are presented in this work. During the first round, 79.2% of photon beams exhibited deviations of less than 3%, while during the second round this photon beam percentage increased to 96.9%. During the first round, 76.4% of the electron beams recorded deviations less than 3% and 12.9% higher than 5%. All brachytherapy sources showed deviations less than 3%. An improvement in dose accuracy was recorded during the subsequent rounds of the audits. (author)

  17. Occupational skin doses in manual implantation of Cs and Ir sources

    The manual handling of sealed 137Cs sources and 192Ir wires for brachytherapy could cause radiation doses to the hand of the operator in excess of 1/10 of the dose limits. This type of work has been monitored in a Radiation Therapy Department for four years using TL finger and wrist dosemeters. The measurements have been re-evaluated to find the average dose equivalent, H'(0.07), to the skin of the hands. The finger dosemeter consisting of two LiF chips in a sachet was calibrated on a Lucite slab phantom. The dose ratio of fingertip/wrist was estimated to be 5. In this type of work the skin dose measured was in the range of 0-43 mSv per month, 1.5 mSv on average. (author)

  18. Influence of radioactive sources discretization in the Monte Carlo computational simulations of brachytherapy procedures: a case study on the procedures for treatment of prostate cancer

    Radiotherapy computational simulation procedures using Monte Carlo (MC) methods have shown to be increasingly important to the improvement of cancer fighting strategies. One of the biases in this practice is the discretization of the radioactive source in brachytherapy simulations, which often do not match with a real situation. This study had the aim to identify and to measure the influence of radioactive sources discretization in brachytherapy MC simulations when compared to those that do not present discretization, using prostate brachytherapy with Iodine-125 radionuclide as model. Simulations were carried out with 108 events with both types of sources to compare them using EGSnrc code associated to MASH phantom in orthostatic and supine positions with some anatomic adaptations. Significant alterations were found, especially regarding bladder, rectum and the prostate itself. It can be concluded that there is a need to discretized sources in brachytherapy simulations to ensure its representativeness. (author)

  19. Methodology study for fixation of radioactive iodine in polymeric substrate for brachytherapy sources

    Cancer is now the second leading cause of death by disease in several countries, including Brazil. Prostate cancer is the most common among men. Brachytherapy is a modality of radiotherapy in which radioactive seeds are placed inside or in contact with the organ to be treated. The most widely used radioisotope in prostate brachytherapy is Iodine-125 which is presented fixated on a silver substrate that is subsequently placed inside a titanium capsule. A large dose of radiation is released only in the targeted tumor protecting healthy surrounding tissues. The technique requires the application of 80 - 120 seeds per patient. The implants of seeds have low impact and non-surgical procedures. Most patients can return to normal life within three days with little or no pain. This work proposes an alternative to the seeds that have already been developed, in order to reduce the cost by obtaining a better efficiency on fixing the radioactive iodine onto the epoxy resin. Methods have been developed to perform the fixation of Iodine-125 onto polymeric substrates. The parameters analyzed were the immersion time, type of static or dynamic reaction, concentration of the adsorption solution, the specific activity of the radioactive source, the need for carrier and chemical form of the radioactive Iodine. These experiments defined the most effective method to fixate the Iodine onto the polymeric material (epoxy resin), the Iodine activity in the polymeric substrate, the activity of the distribution of variation in a plot of polymeric cores and the efficiency of the epoxy resin to seal the seed. (author)

  20. Methodology study for fixation of radioactive iodine in polymeric substrate for brachytherapy sources

    Rodrigues, Bruna T.; Rostelato, Maria Elisa C.M.; Souza, Carla D.; Tiezzi, Rodrigo; Souza, Daiane B. de; Benega, Marcos A.G.; Souza, Anderson S. de; Peleias Junior, Fernando S.; Zeituni, Calos A.; Fernandes, Vagner; Melo, Emerson Ronaldo de; Camargo, Anderson Rogerio de, E-mail: bteigarodrigues@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Cancer is now the second leading cause of death by disease in several countries, including Brazil. Prostate cancer is the most common among men. Brachytherapy is a modality of radiotherapy in which radioactive seeds are placed inside or in contact with the organ to be treated. The most widely used radioisotope in prostate brachytherapy is Iodine-125 which is presented fixated on a silver substrate that is subsequently placed inside a titanium capsule. A large dose of radiation is released only in the targeted tumor protecting healthy surrounding tissues. The technique requires the application of 80 - 120 seeds per patient. The implants of seeds have low impact and non-surgical procedures. Most patients can return to normal life within three days with little or no pain. This work proposes an alternative to the seeds that have already been developed, in order to reduce the cost by obtaining a better efficiency on fixing the radioactive iodine onto the epoxy resin. Methods have been developed to perform the fixation of Iodine-125 onto polymeric substrates. The parameters analyzed were the immersion time, type of static or dynamic reaction, concentration of the adsorption solution, the specific activity of the radioactive source, the need for carrier and chemical form of the radioactive Iodine. These experiments defined the most effective method to fixate the Iodine onto the polymeric material (epoxy resin), the Iodine activity in the polymeric substrate, the activity of the distribution of variation in a plot of polymeric cores and the efficiency of the epoxy resin to seal the seed. (author)

  1. Chemical digestion and radionuclidic assay of TiNi-encapsulated 32P intravascular brachytherapy sources

    A very quantitative, destructive assay procedure was devised for accurately measuring the 32P activity content of TiNi-encapsulated intravascular brachytherapy sources and was applied to four different sources (termed 'seeds') which were developed and provided by Guidant Intravascular Intervention (formerly NeoCardia). These seeds are intended for use in the prophylactic treatment of restenosis following balloon angioplasty in heart-disease patients. The assays involved the dissolution of the TiNi jacket, extraction of the activity from the internal 32P-containing source material, quantitative solution transfers, and a gravimetrically-based dilution; followed by liquid scintillation (LS) spectrometry of the resulting master solution with 3H-standard efficiency tracing using composition-matched LS cocktails. The LS spectrometry utilized a previously-developed method for resolving the always-present 33P impurity. The protocol included provisions for accounting for all possible losses of 32P in the digestion procedure (based on radiochemical tracing experiments), for any unrecovered activity in the remaining source material, and for any residual activity in the solution-transfer and containing vessels. Sections of the TiNi jackets adjacent to the cut-off active seed portions were also assayed for any contained activity. Such destructive assays were required for relating measurements of the absorbed dose spatial distribution for the seeds to theoretic dose modelling and for establishing calibration factors for subsequent non-destructive radionuclidic measurements on the seeds

  2. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 ± 0.531 M Bq and kerma in air 0.03200 ± 0.00006 m Gy m/h A. (Author)

  3. Proposal of a postal system for Ir-192 sources calibration used in high dose rate brachytherapy with LiF:Mn:Ti thermoluminescent dosemeters

    A proposal in order to improve the brachytherapy quality control and to allow postal intercomparison of Ir-192 sources used in high dose rate brachytherapy has been presented. The LiF: Mn: Ti (TLD 100) detector has been selected for such purpose. The experimental array and the TLDs irradiation and calibration techniques, at the treatment units, have been specified in the light of more recent methodology of Ir-192 calibration sources. (Author)

  4. Re-evaluation of the shielding adequacy of the brachytherapy treatment room at Korle-Bu teaching hospital, Ghana

    Staff and the general public's safety during the operation of the 137Cs brachytherapy unit at the Korle Bu teaching hospital depends on the adequacy of the shielding of the facility. Shielding design of the brachytherapy unit at the hospital was based on postulated workload and postulated occupancy factors to critical locations at the facility where the public and staff may occupy. This facility has been in existence for the past twelve (12) years and has accumulated operational workload data which differs from the postulated one. A study was carried out to re-evaluate the integrity of the biological shielding of the 137Cs brachytherapy unit. This study analyzed the accumulated workload data and used the information to perform shielding calculations to verify the adequacy of the biological shielding thicknesses to provide sufficient protection of staff and the public. Dose rate calculations were verified by measurements with calibrated dose rate meters. This provided the basis for determining the current state of protection and safety for staff and the general public. The results show that despite the variation in actual and postulated workloads, the dose rates were below the reference values of 0.5μSv/h for public areas and 7.5μSv/h for controlled areas. It was confirmed that the present shielding thickness of 535 mm can accommodate a high dose rate (HDR) 192Ir source with activity in the range 370 - 570 GBq with an operational workload of 30 patients per week and an average treatment time of 10 minutes.

  5. Manual calculation of treatment time for high dose rate brachytherapy with a flexible intraoperative template (FIT)

    A method is presented for estimating the total treatment time for a brachytherapy radiation fraction with a planar flexible intraoperative template (FIT), using an 192Ir high dose rate afterloading device. The FIT can be rectangular or irregularly shaped. The manual calculation serves as an independent check of the treatment time calculated by the treatment planning system for applications with varying sizes, shapes and dose prescription depths. The parameters required for the calculation are the number of active dwell positions, the catheter spacing and dwell position spacing, the source strength, the applied dose and the depth of dose prescription. For a fixed depth of dose prescription (1.25 cm) and fixed dwell position and catheter spacing (0.5 and 1 cm respectively) the manual calculation accurately predicts (usually within 2%) the total treatment time as calculated by the treatment planning system. For varying catheter and dwell position spacings and dose prescription depths the accuracy is still within 7%. An action threshold of 5% allows detection of errors made in the number of active dwell positions (±9), catheter spacing (±1 mm) and dose prescription depth (±1 mm). Errors in dwell position spacing (0.25 cm or more) could also be accurately detected. (author)

  6. Chemonuclear studies for identification for new production routes for the therapeutically useful radionuclides 140Nd, 192Ir, 191Pt, 193mPt, und 195mPt

    New production routes for the therapeutically useful radionuclides 140Nd, 192Ir, 191Pt, 193mPt and 195mPt were investigated. Cross section data were measured using the stacked-foil technique and compared with theoretical calculations. A production method for the platinum nuclides was developed. The 141Pr(p, 2n)140Nd and natCe(3He, xn)140Nd reactions were investigated for production of 140Nd. Cross section data of nuclear reactions leading to the side products 141Nd, 139Nd and 139Ce could also be achieved. The experimental data were compared with theoretical calculations using the code ALICE-IPPE. A comparison of the calculated thick target yields showed that the 141Pr(p, 2n)140Nd reaction gives a higher yield. The 192Os(p, n)192Ir reaction was examined in the context of the production of 192Ir. Cross section data were determined and compared with theoretical calculations using the codes ALICE-IPPE and EMPIRE II. The yield of this reaction was compared with the yield of the reactor production of this nuclide. The reactor production seems to be more suitable because of a higher purity and yield. Cross section data were measured for the 192Os(α, n)195mPt, 192Os(α, 3n)193mPt and 192Os(3He, 4n)191Pt reactions. The activity of 193mPt and 195mPt was determined by X-ray spectroscopy after a chemical separation procedure. The ALICE-IPPE code was found to be inappropriate to reproduce the experimental values. The calculated yields were compared with the yields of other reactions, especially the reactor production of 195mPt. The yield of the 192Os(α, n)195mPt reaction is lower compared to the yield of the reactor production, but offers lower target costs and higher specific activity. A production method for 193mPt and 195mPt was developed. Batch yields of 0.9 MBq 195mPt (specific activity of about 150 GBq/g Pt) and 8.7 MBq 193mPt (ca. 3 TBq/g Pt) could be achieved. The experimental yields were compared with the calculated yields. The agreement between these two data sets

  7. Monte Carlo characterization of the Gamma-Med Hdr plus Ir-192 brachytherapy source

    Full text: The MCNP4C Monte Carlo code was used to simulate the dosimetry around the Gamma-Med Hdr Plus iridium-192 brachytherapy source in both air/vacuum and water environments. Dosimetry data in water was calculated and are presented into an away-along table. All dosimetric quantities recommended by the AAPM Task Group 43 report have been also calculated. These quantities are air kerma strength, dose rate constant, radial dose function and anisotropy function. The obtained data are compared to this source reference data, finding results in good agreement with them. In this study, recommendations of the AAPM TG-43U1 report have been followed and comply with the most recent AAPM and ESTRO physics committee recommendations about Monte Carlo techniques. The data in the present study complement published data and can be used as input in the Tps or as benchmark data to verify the results of the treatment planning systems as well as a means of comparison with other datasets from this source. (Author)

  8. Monte Carlo characterization of the Gamma-Med Hdr plus Ir-192 brachytherapy source

    Reyes, E.; Sosa, M. A.; Gil V, A. [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Av. Insurgentes 2354, 37150 Leon, Guanajuato (Mexico); Monzon, E., E-mail: eric_1985@fisica.ugto.mx [IMSS, Unidad Medica de Alta Especialidad No. 1, Av. Adolfo Lopez Mateos 1813, 37340 Leon, Guanajuato (Mexico)

    2015-10-15

    Full text: The MCNP4C Monte Carlo code was used to simulate the dosimetry around the Gamma-Med Hdr Plus iridium-192 brachytherapy source in both air/vacuum and water environments. Dosimetry data in water was calculated and are presented into an away-along table. All dosimetric quantities recommended by the AAPM Task Group 43 report have been also calculated. These quantities are air kerma strength, dose rate constant, radial dose function and anisotropy function. The obtained data are compared to this source reference data, finding results in good agreement with them. In this study, recommendations of the AAPM TG-43U1 report have been followed and comply with the most recent AAPM and ESTRO physics committee recommendations about Monte Carlo techniques. The data in the present study complement published data and can be used as input in the Tps or as benchmark data to verify the results of the treatment planning systems as well as a means of comparison with other datasets from this source. (Author)

  9. Quality assurance programme in high dose rate brachytherapy with Iridium-192 source. Recommendations of the French Medical Physicists Society

    A report on Quality Assurance in High Dose Rate brachytherapy with Iridium-192 source has been prepared by the task group of the Brachytherapy committee of the French Medical Physicists Society. This report provides recommendations on what should be tested, the methods to be used, the test frequencies and the tolerances. The Quality Assurance Programme concerns mainly the Q.A. on the treatment unit, the treatment planning system and the patient procedure. Tolerances and action levels are linked to international recommendations. Safety standards are linked to national legislation and to international recommendations. It is the responsibility of the Institution to verify that the source calibration provided by the manufacturer is correct. The calibration of the Iridium-192 source should be an in-air measurement of air-kerma using an ionization chamber. The recommended tolerance between manufacturer and Institution calibration is 3 %. Quality Control on remote afterloading systems should include consideration of the accuracy and reproducibility of positioning of sources in the applicators. Safety features must also be evaluated regularly and emergency procedures should be tested regularly and posted in a prominent place. After the detailed acceptance tests of dose calculation algorithm, routine checks should be done after software update. An independent dose calculation is recommended before treatment. The recommended agreement with the computer calculation should be within 10%. A written dosimetry report for each brachytherapy procedure is recommended to be inserted in patient charts. The results of all tests should be recorded in a logbook. Fault conditions should be carefully documented

  10. In vivo dosimetry HDR brachytherapy prostate with source CO-60: Results of measures in a point urethra

    In this study we present and analyze the results of the in vivo dosimetry made a point of urethra with a group of 30 patients treated with brachytherapy prostate high rate with Co-60 source. Taking into account the uncertainties, the results and integration, globally evaluate this system DIV. This DIV system, due to its ease of calibration and use, and provides a relatively simple integration way to avoid serious errors in administering treatment. (Author)

  11. Overview on the dosimetric uncertainty analysis for photon-emitting brachytherapy sources, in the light of the AAPM Task Group No 138 and GEC-ESTRO report

    In 2011, the American Association of Physicists in Medicine (AAPM) and the Groupe Europeen de Curietherapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) published a report pertaining to uncertainties in brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization's Guide to the Expression of Uncertainty in Measurement and Technical Note 1297 by the National Institute of Standards and Technology are taken as reference standards for uncertainty formalism. Uncertainties involved in measurements or Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is given with uncertainties in each of the brachytherapy dosimetry parameters of the AAPM TG-43 dose-calculation formalism. For low-energy and high-energy brachytherapy sources of low dose-rate and high dose-rate, a combined dosimetric uncertainty ≤5% (k = 1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and manufacturers of brachytherapy sources and treatment planning systems. These recommendations reflect the guidance of the AAPM and GEC-ESTRO for their members, and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for conventional brachytherapy sources used in routine clinical treatments. (authors)

  12. Pathological characteristics of extremely severe acute radiation injury in a patient's legs and hands after a very uneven accidental exposure to an extremely high dose of 192Ir

    The pathological characteristics of an extremely high dose radiation in the legs and hands of a patient is reported. the patient was exposed to 192Ir γ-rays for 9 hours and 20 minutes, the activity of which was 2.76 TBq. The amputations of the right thigh and left forearm had to be performed 8 days after the irradiation and the debridements and skin graftings were performed on the right hand and the inner side of left knee 55 days after the radiation. Microscopically, massive necrosis of cells of the epidermis, cutaneous appendages, hypodermics and skeletal muscles, and hemorrhage in the dermis, hypodermics and skeletal muscles were seen in the local irradiated parts of the right shank. But the arrector pili muscles in the dermis of the right shank remained. On the fingers and the palm of the left hand, vacuolar degeneration and massive necrosis of the cells of epidermis were present with extensive neutrophil infiltration. Cysts of large or small size were formed from the necrotic cells, separating epidermis from dermis. There were degeneration and necrosis of glandular epithelium cells of sweat glands. Hemorrhage was present in dermis and hypodermics. All the hematopoietic tissues in the bone marrow in the upper ends of the tibia and fibula and in the lower ends of the femur, the radius and the ulna disappeared. Acute radiation ulcers were present on the skin of the left knee and on the skin of the thumb, index finger and middle finger of the right hand. The extremely severe acute radiation injury caused by extremely high dose of 192Ir led to the necrosis of the extensive soft tissues deep to skeletal muscles and the disappearance of the hematopoietic tissues in the bone marrow

  13. Calculation of the dynamic component of the radiation dose in HDR brachytherapy based on Monte Carlo simulations

    A method for the calculation of the transit doses in HDR brachytherapy based on Monte Carlo simulations has been presented. The transit doses resulting from a linear implant with seven dwell positions is simulated by performing calculations at all positions in which, the moving 192Ir source, instantaneously, had its geometrical centre located exactly between two adjacent dwell positions. Discrete step sizes of 0.25 cm were used to calculate the dose rates and the total transit dose at any of the calculation points evaluated. By comparing this method to the results obtained from Sievert Integrals, we observed dose calculation errors ranging from 32 to 21% for the examples considered. The errors could be much higher for longer treatment lengths where contributions from points near the longitudinal axis of the source become more important. To date, the most accurate method of calculating doses in radiotherapy is by Monte Carlo Simulations but the long computational times associated with it renders its use in treatment planning impracticable. The Sievert Integral algorithms on the other hand are simple, versatile and very easy to use but its accuracy had been repeatedly put into question for low energy isotopes like iridium. We therefore advocate a modification of the Sievert Integral algorithms by superimposing the output from Monte Carlo Simulations on the Sievert Integrals when dealing with low energy isotopes. In this way, we would be combining accuracy, simplicity and reasonable computational times (author)

  14. Influences of spherical phantom heterogeneities on dosimetric charactristics of miniature electronic brachytherapy X-ray sources: Monte Carlo study

    Dose calculations in current brachytherapy treatment planning systems (TPS) are commonly based on TG‐43U1 formalism. These TPS are obtained by superposition principle of single‐source dosimetric parameters in liquid water, neglecting the effects of tissue heterogeneity. In this work, the sensitivity of the TG-43U1 based radial dose function (g(r)) of Miniature Electronic Brachytherapy X-ray Sources (MEBXS) to bone-heterogeneity was examined. To quantify the heterogeneity effects for g(r), a series of Monte Carlo (MC) based radiation transport simulations at the center of homogeneous and heterogeneous spherical phantoms were performed using the MCNP5 code. The ratio of the g(r) in the heterogeneius phantom to the uniform soft tisuue phantom as a function of the bone thickness was determined. These results indicated that for 40 keV beam, the maximum ratios for thicknesses of 1 cm and 2 cm were 3.36 and 3.27, respectively. These values changed to 4.28 and 4.06, for 60 keV beam, respectively. Introduction of 0.5 cm or 1 cm red marrow, into the interior of the cortical bone changed the maximum variations to, 3.54, and 3.57 for 40 keV, and 4.28, and 4.25, for 60 keV, respectively. - Highlights: • Monte Carlo simulation was used to model the bone heterogeneity for Electronic Brachytherapy. • Variation of the TG-43U1 radial dose function is dependent to bone thickness and is higher than the water phantom. • For skin cancer treatment in sites which is close immediately to the bone, the bone damage is higher than the skin tissue. • To spare the bone in skin treatment (i.e. scalp, legs) bone heterogeneity effect should be applied to the electronic brachytherapy dosimetric

  15. A novel optical calorimetry dosimetry approach applied to an HDR Brachytherapy source

    The technique of Digital Holographic Interferometry (DHI) is applied to the measurement of radiation absorbed dose distribution in water. An optical interferometer has been developed that captures the small variations in the refractive index of water due to the radiation induced temperature increase ΔT. The absorbed dose D is then determined with high temporal and spatial resolution using the calorimetric relation D=cΔT (where c is the specific heat capacity of water). The method is capable of time resolving 3D spatial calorimetry. As a proof-of-principle of the approach, a prototype DHI dosimeter was applied to the measurement of absorbed dose from a High Dose Rate (HDR) Brachytherapy source. Initial results are in agreement with modelled doses from the Brachyvision treatment planning system, demonstrating the viability of the system for high dose rate applications. Future work will focus on applying corrections for heat diffusion and geometric effects. The method has potential to contribute to the dosimetry of diverse high dose rate applications which require high spatial resolution such as microbeam radiotherapy (MRT) or small field proton beam dosimetry but may potentially also be useful for interface dosimetry.

  16. Fabrication of Miniature Titanium Capsule for Brachytherapy Sources Using Tungsten Inert Gas Method

    The capsules containing radioactive materials as brachytherapy sources are used for implanting into some target organs for malignant disorders treatments, such as prostate, eyes, and brain cancers. The conventional method for sealing the tubes is to weld them using a laser beam which is now a part of tube melting methods (self welding). The purpose of this study was to seal miniature titanium tubes containing radioactive materials in the form of capsules. This study introduced a new method based on melting process. A piece of commercially pure titanium grade 2 in the form of disk was used for the experiment. The sample was melted at the top of the tube by a Tungsten Inert Gas welding device for a short time duration. After completion of the melting, the disk in the form of a drop was mixed with a small part of it and both were solidified and hence closed the tube. We evaluated the tubes for the metallurgical properties and seal process which took place by Tungsten Inert Gas in different zones, including the heat affected zone, fusion zone, and interface of the joint of the drop to the tube. Finally, the produced samples were tested according to the ISO2919 and ISO9978 and the results confirmed the Disk and Tungsten Inert Gas procedure.

  17. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of 125I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for 125I selectSeedTM brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and changes in the

  18. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel [Servicio de Radiofísica y Protección Radiológica, Hospital Universitario San Cecilio, E-18012 Granada (Spain); Perez-Calatayud, Jose [Servicio de Radioterapia, Unidad de Radiofísica, Hospital Universitario y Politécnico La Fe, E-46026 Valencia (Spain); Simancas, Fernando; Lallena, Antonio M. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Gazdic-Santic, Maja [Department of Medical Physics and Radiation Safety, Clinical Centre of Sarajevo University, 71000 Sarajevo (Bosnia and Herzegovina)

    2013-12-15

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and

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

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

  20. Automation system for quality control in manufacture of iodine-125 sealed sources used in brachytherapy

    Somessari, Samir L.; Feher, Anselmo; Sprenger, Francisco E.; Rostellato, Maria E.C.M.; Moura, Joao A.; Costa, Osvaldo L.; Calvo, Wilson A.P., E-mail: somessar@ipen.b, E-mail: afeher@ipen.b, E-mail: sprenger@ipen.b, E-mail: elisaros@ipen.b, E-mail: olcosta@ipen.b, E-mail: wapcalvo@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The objective of this work is to develop an automation system for Quality Control in the production of Iodine-125 sealed sources, after undergoing the process of laser beam welding. These sources, also known as Iodine-125 seeds are used, successfully, in the treatment of cancer by brachytherapy, with low-dose rates. Each small seed is composed of a welded titanium capsule with 0.8 mm diameter and 4.5 mm in length, containing Iodine-125 adsorbed on an internal silver wire. The seeds are implanted in the human prostate to irradiate the tumor and treat the cancerous cells. The technology to automate the quality control system in the manufacture of Iodine-125 seeds consists in developing and associate mechanical parts, electronic components and pneumatic circuits to control machines and processes. The automation technology for Iodine-125 seed production developed in this work employs programmable logic controller, step motors, drivers of control, electrical-electronic interfaces, photoelectric sensors, interfaces of communication and software development. Industrial automation plays an important role in the production of Iodine-125 seeds, with higher productivity and high standard of quality, facilitating the implementation and operation of processes with good manufacturing practices. Nowadays, the Radiation Technology Center at IPEN-CNEN/SP imports and distributes 36,000 Iodine-125 seeds per year for clinics and hospitals in the whole country. However, the Brazilian potential market is of 8,000 Iodine-125 seeds per month. Therefore, the local production of these radioactive seeds has become a priority for the Institute, aiming to reduce the price and increase the supply to the population in Brazil. (author)

  1. Automation system for quality control in manufacture of iodine-125 sealed sources used in brachytherapy

    The objective of this work is to develop an automation system for Quality Control in the production of Iodine-125 sealed sources, after undergoing the process of laser beam welding. These sources, also known as Iodine-125 seeds are used, successfully, in the treatment of cancer by brachytherapy, with low-dose rates. Each small seed is composed of a welded titanium capsule with 0.8 mm diameter and 4.5 mm in length, containing Iodine-125 adsorbed on an internal silver wire. The seeds are implanted in the human prostate to irradiate the tumor and treat the cancerous cells. The technology to automate the quality control system in the manufacture of Iodine-125 seeds consists in developing and associate mechanical parts, electronic components and pneumatic circuits to control machines and processes. The automation technology for Iodine-125 seed production developed in this work employs programmable logic controller, step motors, drivers of control, electrical-electronic interfaces, photoelectric sensors, interfaces of communication and software development. Industrial automation plays an important role in the production of Iodine-125 seeds, with higher productivity and high standard of quality, facilitating the implementation and operation of processes with good manufacturing practices. Nowadays, the Radiation Technology Center at IPEN-CNEN/SP imports and distributes 36,000 Iodine-125 seeds per year for clinics and hospitals in the whole country. However, the Brazilian potential market is of 8,000 Iodine-125 seeds per month. Therefore, the local production of these radioactive seeds has become a priority for the Institute, aiming to reduce the price and increase the supply to the population in Brazil. (author)

  2. Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for 125I and 103Pd brachytherapy sources relative to 60Co

    Purpose: To determine the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters (TLD-100) for 125I and 103Pd brachytherapy sources relative to 60Co. Methods: LiF:Mg,Ti TLDs were irradiated with low-energy brachytherapy sources and with a 60Co teletherapy source. The brachytherapy sources measured were the Best 2301 125I seed, the OncoSeed 6711 125I seed, and the Best 2335 103Pd seed. The TLD light output per measured air-kerma strength was determined for the brachytherapy source irradiations, and the TLD light output per air kerma was determined for the 60Co irradiations. Monte Carlo (MC) simulations were used to calculate the dose-to-TLD rate per air-kerma strength for the brachytherapy source irradiations and the dose to TLD per air kerma for the 60Co irradiations. The measured and MC-calculated results for all irradiations were used to determine the TLD intrinsic energy dependence for 125I and 103Pd relative to 60Co. Results: The relative TLD intrinsic energy dependences (relative to 60Co) and associated uncertainties (k = 1) were determined to be 0.883 ± 1.3%, 0.870 ± 1.4%, and 0.871 ± 1.5% for the Best 2301 seed, OncoSeed 6711 seed, and Best 2335 seed, respectively. Conclusions: The intrinsic energy dependence of TLD-100 is dependent on photon energy, exhibiting changes of 13%–15% for 125I and 103Pd sources relative to 60Co. TLD measurements of absolute dose around 125I and 103Pd brachytherapy sources should explicitly account for the relative TLD intrinsic energy dependence in order to improve dosimetric accuracy

  3. Interstitial brachytherapy dosimetry update

    In March 2004, the American Association of Physicists in Medicine (AAPM) published an update to the AAPM Task Group No. 43 Report (TG-43) which was initially published in 1995. This update was pursued primarily due to the marked increase in permanent implantation of low-energy photon-emitting brachytherapy sources in the United States over the past decade, and clinical rationale for the need of accurate dosimetry in the implementation of interstitial brachytherapy. Additionally, there were substantial improvements in the brachytherapy dosimetry formalism, accuracy of related parameters and methods for determining these parameters. With salient background, these improvements are discussed in the context of radiation dosimetry. As an example, the impact of this update on the administered dose is assessed for the model 200 103Pd brachytherapy source. (authors)

  4. Chemonuclear studies for identification for new production routes for the therapeutically useful radionuclides {sup 140}Nd, {sup 192}Ir, {sup 191}Pt, {sup 193m}Pt, und {sup 195m}Pt; Kernchemische Studien zur Entwicklung neuerer Produktionsverfahren fuer die therapierelevanten Radionuklide {sup 140}Nd, {sup 192}Ir, {sup 191}Pt, {sup 193m}Pt, und {sup 195m}Pt

    Hilgers, K.

    2005-12-15

    New production routes for the therapeutically useful radionuclides {sup 140}Nd, {sup 192}Ir, {sup 191}Pt, {sup 193m}Pt and {sup 195m}Pt were investigated. Cross section data were measured using the stacked-foil technique and compared with theoretical calculations. A production method for the platinum nuclides was developed. The {sup 141}Pr(p, 2n){sup 140}Nd and {sup nat}Ce({sup 3}He, xn){sup 140}Nd reactions were investigated for production of {sup 140}Nd. Cross section data of nuclear reactions leading to the side products {sup 141}Nd, {sup 139}Nd and {sup 139}Ce could also be achieved. The experimental data were compared with theoretical calculations using the code ALICE-IPPE. A comparison of the calculated thick target yields showed that the {sup 141}Pr(p, 2n){sup 140}Nd reaction gives a higher yield. The {sup 192}Os(p, n){sup 192}Ir reaction was examined in the context of the production of {sup 192}Ir. Cross section data were determined and compared with theoretical calculations using the codes ALICE-IPPE and EMPIRE II. The yield of this reaction was compared with the yield of the reactor production of this nuclide. The reactor production seems to be more suitable because of a higher purity and yield. Cross section data were measured for the {sup 192}Os({alpha}, n){sup 195m}Pt, {sup 192}Os({alpha}, 3n){sup 193m}Pt and {sup 192}Os({sup 3}He, 4n){sup 191}Pt reactions. The activity of {sup 193m}Pt and {sup 195m}Pt was determined by X-ray spectroscopy after a chemical separation procedure. The ALICE-IPPE code was found to be inappropriate to reproduce the experimental values. The calculated yields were compared with the yields of other reactions, especially the reactor production of {sup 195m}Pt. The yield of the {sup 192}Os({alpha}, n){sup 195m}Pt reaction is lower compared to the yield of the reactor production, but offers lower target costs and higher specific activity. A production method for {sup 193m}Pt and {sup 195m}Pt was developed. Batch yields of 0.9 MBq

  5. Development of methods for activity determination for radionuclides with double decay emission β- β+ / electron capture - application to the standardization of 192Ir, 152Eu and 186 Re

    In the present work alternative procedures have been developed for standardization of radionuclides with double decay, β- β+ / electron capture using the 4πβ-γ coincidence technique, applying different systems. Two 4πβ-γ coincidence systems were used: one with a 4π gas-flow proportional counter coupled to a pair of NaI(Tl) scintillators and the other one with the same type of proportional counter coupled to HPGe detector. The radionuclides selected for this standardization, due to great interest in nuclear medicine, detector calibration and industrial radiography, were 192Ir, 152Eu and 186 Re. The first and the second were part of international comparisons sponsored by the Bureau International des Poids et Mesures (BIPM), France, who supplied the radioactive solution. For 186Re, the gamma-ray emission probability per decay was measured by means REGe spectrometer system, previously calibrated with standard ampoules. All the uncertainties involved were treated rigorously, by means of covariance analysis. (author)

  6. Production techniques and quality control of sealed radioactive sources of palladium-103, iodine-125, iridium-192 and ytterbium-169. Final report of a coordinated research project 2001-2005

    Radioisotopes have been used extensively for many years for several medical and industrial applications either in the form of an open source or encapsulated in an appropriate metallic container (sealed source). The design and technology for the preparation of radioactive sealed sources is an area of continuous development to satisfy an ever increasing demand for a larger variety of shapes, sizes, type of radioisotope and levels of radioactivity required for newer and specialized applications. In medicine, sealed sources using the radioisotopes of 125I, 192Ir and 103Pd are commonly used for brachytherapy for the treatment of malignant diseases, and for bone density measurements. In industry, they are widely used for non-destructive testing (NDT), radiation processing, 'on-line' process control systems and on-line elemental analysis of mineral resources. Some well-known examples of such sources are 60Co for industrial nucleonic gauges, 192Ir sources for industrial radiography, 241Am sources for smoke detectors and chemical analysers and, more recently, 169Yb for NDT measurements of thin metallic tubes and plates. The current challenges in development include the production of miniature size sources with a high level of activity, a high degree of uniformity in the distribution of the radioactivity and the highest degree of safety, requiring stringent quality control methods. The IAEA has been promoting and supporting activities designed to increase the utilization of radiation and radioisotopes in several areas. In particular, in view of the proven benefits of, and an increasing demand for radioactive sealed sources for medical and industrial applications, upon the recommendation of several experts, a Coordinated Research Project (CRP) on Development of Radioactive Sources for Emerging Therapeutic and Industrial Applications was begun in 2002. The aim of the CRP was the optimization and testing of procedures and methods for the fabrication and quality control of

  7. Dosimetric prerequisites for routine clinical use of photon emitting brachytherapy sources with average energy higher than 50 kev

    This paper presents the recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Therapeutic Radiology and Oncology (ESTRO) on the dosimetric parameters to be characterized, and dosimetric studies to be performed to obtain them, for brachytherapy sources with average energy higher than 50 keV that are intended for routine clinical use. In addition, this document makes recommendations on procedures to be used to maintain vendor source strength calibration accuracy. These recommendations reflect the guidance of the AAPM and the ESTRO for its members, and may also be used as guidance to vendors and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments

  8. Implementation of GaN based real-time source position monitoring in HDR brachytherapy

    For High Dose Rate (HDR) brachytherapy Quality Assurance (QA), we propose a seed position verification method by using two GaN dosimetric probes integrated in an instrumented phantom. As dose rate measured from one probe is related to the seed distance, seed position inside catheter can be determined. The proposed two-probe method extends measureable range and improves accuracy in comparison with the use of one single probe. One instrumented phantom implementing the method was designed, fabricated and tested in clinical conditions. The measureable range of the two-probe method is 105 mm compared to 36 mm using single probe. The validity of the method was experimentally verified. - Highlights: • A simple brachytherapy QA phantom has been instrumented. • Dwell positions have been estimated according to measured dose rate by GaN probes. • Measured dose rate shows 1% average deviation from calculated results. • Determined dwell position precision and measureable range was studied

  9. A comparison of the relative biological effectiveness of low energy electronic brachytherapy sources in breast tissue: a Monte Carlo study

    White, Shane A.; Reniers, Brigitte; de Jong, Evelyn E. C.; Rusch, Thomas; Verhaegen, Frank

    2016-01-01

    Electronic brachytherapy sources use low energy photons to treat the tumor bed during or after breast-conserving surgery. The relative biological effectiveness of two electronic brachytherapy sources was explored to determine if spectral differences due to source design influenced radiation quality and if radiation quality decreased with distance in the breast. The RBE was calculated through the number of DNA double strand breaks (RBEDSB) using the Monte Carlo damage simulator (MCDS) in combination with other Monte Carlo electron/photon spectrum calculations. 50kVp photons from the Intrabeam (Carl Zeiss Surgical) and Axxent (Xoft) through 40-mm spherical applicators were simulated to account for applicator and tissue attenuation in a variety of breast tissue compositions. 40kVp Axxent photons were also simulated. Secondary electrons (known to be responsible for most DNA damage) spectra at different distance were inputted into MCDS to calculate the RBEDSB. All RBEDSB used a cobalt-60 reference. RBEDSB data was combined with corresponding average photon spectrum energy for the Axxent and applied to model-based average photon energy distributions to produce an RBEDSB map of an accelerated partial breast irradiation (APBI) patient. Both Axxent and Intrabeam 50kVp spectra were shown to have a comparable RBEDSB of between 1.4 and 1.6 at all distances in spite of progressive beam hardening. The Axxent 40kVp also demonstrated a similar RBEDSB at distances. Most RBEDSB variability was dependent on the tissue type as was seen in rib (RBEDSB  ≈  1.4), gland (≈1.55), adipose (≈1.59), skin (≈1.52) and lung (≈1.50). RBEDSB variability between both sources was within 2%. A correlation was shown between RBEDSB and average photon energy and used to produce an RBEDSB map of a dose distribution in an APBI patient dataset. Radiation quality is very similar between electronic brachytherapy sources studied. No significant reductions in RBEDSB were observed with

  10. A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a 103Pd source of air-kerma strength 3.4 U (1 U = 1 μGy m2h-1), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries such as eye applicators for treating macular degeneration. (authors)

  11. HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators

    Chibani, Omar, E-mail: omar.chibani@fccc.edu; C-M Ma, Charlie [Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)

    2014-05-15

    Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR

  12. Verification and analysis of the positioning of a source of brachytherapy high dose within an applicator gynecological interstitial fletcher Utrecht TC/RM

    Applicators are guides that circulate and are located within the patient brachytherapy sources. Applicators can suffer mechanical deformations due to processes of sterilization or shock, which may result in that the source do not place within these very precise and coincides with the planned. In these cases the planned treatment deviate actually managed. The object of this study is to verify that the position of the source into the dispenser coincides with the planned position, with a procedure that is described. (Author)

  13. Multidisciplinary treatment for advanced and recurrent breast cancer including brachytherapy

    Tsukiyama, Iwao; Ohno, Tatsuya (Tochigi Cancer Center, Utsunomiya (Japan). Hospital); Takizawa, Yoshikazu; Ikeda, Hiroshi; Egawa, Sunao; Ogino, Takashi

    1994-06-01

    Between 1986 and 1992, 10 patients (12 lesions) of advanced breast cancer were treated with multidisciplinary treatment including brachytherapy. The lesions treated included 5 primary breast tumors, 3 metastatic lesions in the contra lateral breast, 2 recurrences after external beam irradiation, 1 metastasis to the axillary lymph node and 1 metastasis to the upper arm skin. The interstitial irradiation techniques used were [sup 192]Ir low dose-rate irradiation for 5 lesions and high dose-rate for 7 lesions (including 3 with mould irradiation). External hyperthermia as performed for 6 lesions and interstitial hyperthermia were performed for 4 lesions. The local response was CR for 3 lesions, PRa for 8 lesions, PRb for 1 lesion with the local response rate being 100%. Excellent local control could be achieved by combination external and interstitial irradiation, indicating that radiotherapy is definitely useful for the treatment of advanced breast cancer. (author).

  14. Determination of surface dose rate of indigenous 32P patch brachytherapy source by experimental and Monte Carlo methods

    Isotope production and Application Division of Bhabha Atomic Research Center developed 32P patch sources for treatment of superficial tumors. Surface dose rate of a newly developed 32P patch source of nominal diameter 25 mm was measured experimentally using standard extrapolation ionization chamber and Gafchromic EBT film. Monte Carlo model of the 32P patch source along with the extrapolation chamber was also developed to estimate the surface dose rates from these sources. The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and radiochromic films are 82.03±4.18 (k=2) and 79.13±2.53 (k=2) respectively. The two values of the surface dose rates measured using the two independent experimental methods are in good agreement to each other within a variation of 3.5%. The surface dose rate to tissue (cGy/min) estimated using the MCNP Monte Carlo code works out to be 77.78±1.16 (k=2). The maximum deviation between the surface dose rates to tissue obtained by Monte Carlo and the extrapolation chamber method is 5.2% whereas the difference between the surface dose rates obtained by radiochromic film measurement and the Monte Carlo simulation is 1.7%. The three values of the surface dose rates of the 32P patch source obtained by three independent methods are in good agreement to one another within the uncertainties associated with their measurements and calculation. This work has demonstrated that MCNP based electron transport simulations are accurate enough for determining the dosimetry parameters of the indigenously developed 32P patch sources for contact brachytherapy applications. - Highlights: • Surface dose rates of 25 mm nominal diameter newly developed 32P patch sources were measured experimentally using extrapolation chamber and Gafchromic EBT2 film. Monte Carlo model of the 32P patch source along with the extrapolation chamber was also developed. • The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and

  15. PDR brachytherapy with flexible implants for interstitial boost after breast-conserving surgery and external beam radiation therapy

    Background and purpose: For radiobiological reasons the new concept of pulsed dose rate (PDR) brachytherapy seems to be suitable to replace traditional CLDR brachytherapy with line sources. PDR brachytherapy using a stepping source seems to be particularly suitable for the interstitial boost of breast carcinoma after breast-conserving surgery and external beam irradiation since in these cases the exact adjustment of the active lengths is essential in order to prevent unwanted skin dose and consequential unfavorable cosmetic results. The purpose of this study was to assess the feasibility and morbidity of a PDR boost with flexible breast implants. Materials and methods: Sixty-five high risk patients were treated with an interstitial PDR boost. The criteria for an interstitial boost were positive margin or close margin, extensive intraductal component (EIC), intralymphatic extension, lobular carcinoma, T2 tumors and high nuclear grade (GIII). Dose calculation and specification were performed following the rules of the Paris system. The dose per pulse was 1 Gy. The pulse pauses were kept constant at 1 h. A geometrically optimized dose distribution was used for all patients. The treatment schedule was 50 Gy external beam to the whole breast and 20 Gy boost. PDR irradiations were carried out with a nominal 37 GBq 192-Ir source. Results: The median follow-up was 30 months (minimum 12 months, maximum 54 months). Sixty percent of the patients judged their cosmetic result as excellent, 27% judged it as good, 11% judged it as fair and 2% judged it as poor. Eighty-six percent of the patients had no radiogenous skin changes in the boost area. In 11% of patients minimal punctiform telangiectasia appeared at single puncture sites. In 3% ((2(65))) of patients planar telangiectasia appeared on the medial side of the implant. The rate of isolated local recurrences was 1.5%. In most cases geometrical volume optimization (GVO) yields improved dose distributions with respect to

  16. Required treatment margin for coronary endovascular brachytherapy with iridium-192 seed ribbon

    Purpose: Preliminary clinical trials (SCRIPPS I, WRIST and Gamma 1) employing catheter-based endovascular brachytherapy (EVBT) with iridium-192 (Ir-192) seeds show promising results in reducing restenosis after coronary intervention. Failure analysis of these studies showed a significant number of restenosis at the treatment margin called ''edge effect.'' The objective of this study is to investigate the factors that contribute to the adequacy of treatment margin. Methods and materials: The factors contributing to the margins are penumbra effect at the end of the seed train, uncertainty in target localization, longitudinal seed movement during cardiac cycle and barotrauma due to stent deployment. The magnitudes of the penumbra effect, which refers to the tapering off the prescribed isodose line near the ends of the source train, were calculated for various source lengths of Ir-192 seed ribbon using AAPM TG-43 algorithm. Uncertainty in target localization refers to the fact that the visual estimation of proximal and distal extent of the injury is not accurate, and this can be obtained by comparing the 'estimate' from the interventional cardiologist with careful review of the cine-angiogram. Longitudinal seed movements relative to the coronary vessel during the cardiac cycle were determined by frame-by-frame reviewing cine-angiograms of 30 patients. The proximal and distal source points were measured in reference to branching vessels during the contrast phase of the cine-angiogram. The maximum proximal and distal longitudinal movement was captured and source displacement was measured from the closest proximal and distal branching vessel. Barotrauma, additional injury to the vessel arising from the stent deployment balloon, was obtained by reviewing specifications from commercially available stent delivery systems. Results: The penumbra effect ranges from 3.9 to 4.5 mm for 6-22 Ir-192 seed ribbons. The uncertainty in target localization is within 3 mm for our

  17. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of 192Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results indicate an

  18. New brachytherapy standards paradigm shift

    deviations). Moreover, the determination of Λ relies on Monte Carlo simulations or relative measurements performed with passive dosimeters and therefore it is typically affected by an uncertainty greater than 5% (at the level of one standard deviation). Taking into account the uncertainties in algorithms for treatment planning dose, the procedures to determine the absorbed dose imparted to the patient in BT treatments, are currently affected by an uncertainty higher than the limit recommended of 5% (at the level of one standard deviation). A significant part of this uncertainty is due to a lack of metrology: no absorbed dose primary standards are currently used to calibrate BT sources and the conversion procedure needed for BT dosimetry is a source of additional uncertainty on the final value of the absorbed dose imparted to the patient. Many national medical associations and scientific international organizations- like ESTRO (European Society for Therapeutic Radiology and Oncology), IAEA (International Atomic Energy Agency), ICRU (International Commission on Radiation Units and Measurement) and BIPM (Bureau International des Poids et Mesures)- started research programs in the field of BT and encouraged the metrological community to develop direct absorbed dose standards for BT. The initiatives launched in recent years in response to this request are now well advanced. A standard for direct measurements of absorbed dose to water in HDR 1921 BT based on 4 oC stagnant calorimetry) is described. The estimated overall uncertainty on this standard amounts to 1,90 % (at the level of one standard deviation). In July 2008, a BT joint research project started within the European Association of National Metrology Institutes (EURAMET e.V.) aiming to develop seven standards for more direct measurements of absorbed dose to water at clinically relevant distances. The standards developed for measurement with high dose rate (HDR) BT sources (as 192Ir) are based on graphite and water

  19. CT-guided high-dose-rate brachytherapy of unresectable hepatocellular carcinoma

    Collettini, Federico; Schreiber, Nadja; Schnapauff, Dirk; Denecke, Timm; Hamm, Bernd; Gebauer, Bernhard [ChariteUniversitaetsmedizin Berlin, Department of Diagnostic and Interventional Radiology, Berlin (Germany); Wust, Peter [ChariteUniversitaetsmedizin Berlin, Department of Radiation Oncology, Berlin (Germany); Schott, Eckart [Universitaetsmedizin Berlin, Department of Gastroenterology, Berlin (Germany)

    2015-05-01

    The purpose of the present study was to evaluate the clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) in patients with unresectable hepatocellular carcinoma (HCC). Over a 6-year period, 98 patients with 212 unresectable HCC underwent CT-HDRBT applying a {sup 192}Ir source at our institution. Magnetic resonance imaging (MRI) follow-up was performed 6 weeks after the intervention and then every 3 months. The primary endpoint was local tumor control (LTC); secondary endpoints included progression-free survival (PFS) and overall survival (OS). Patients were available for MRI evaluation for a mean follow-up of 23.1 months (range 4-64 months; median 20 months). Mean tumor diameter was 5 cm (range 1.8-12 cm). Eighteen of 212 (8.5 %) tumors showed local progression after a mean LTC of 21.1 months. In all, 67 patients (68.4 %) experienced distant tumor progression. The mean PFS was 15.2 months. Forty-six patients died during the follow-up period. Median OS was 29.2 months. Actuarial 1-, 2-, and 3-year OS rates were 80, 62, and 46 %, respectively. CT-HDRBT is an effective therapy to attain local tumor control in patients with unresectable HCC. Prospective randomized studies comparing CT-HDRBT with the standard treatments like Radiofrequency ablation (RFA) and chemoembolization (TACE) are mandatory. (orig.) [German] Zweck der vorliegenden Arbeit war die Analyse der klinischen Effektivitaet der CT-gesteuerten Hochdosis-Brachytherapie (CT-HDRBT) bei Patienten mit inoperablem hepatozellulaeren Karzinom (HCC). Ueber einen Zeitraum von 6 Jahren, wurden an unserer Klinik 98 Patienten mit 212 inoperablen HCC mittels CT-HDRBT mit {sup 192}Ir behandelt. MRT-Verlaufskontrollen erfolgten 6 Wochen nach der Intervention und dann alle 3 Monate. Primaerer Endpunkt der Studie war die lokale Tumorkontrolle (LTC); sekundaere Endpunkte waren das progressionsfreie Ueberleben (PFS) und Gesamtueberleben (OS). Die mittlere Nachbeobachtungszeit betrug 23,1 Monate (Spanne 4

  20. Interstitial brachytherapy for eyelid carcinoma. Outcome analysis in 60 patients

    Eyelid cancer is a therapeutic challenge due to the cosmetic and functional implications of this anatomical region and the objectives of therapy are tumor control, functional and cosmetic outcome. The present study was performed to analyze local control, toxicity, functional and cosmetic results in patients with eyelid carcinoma treated by interstitial brachytherapy. In this study 60 patients with eyelid carcinoma were treated by interstitial brachytherapy using iridium (192Ir) wires with a linear activity of 1.2-1.7 mCi/cm. The prescription dose was 51-70 Gy (mean 65 Gy, median 66 Gy). Of the 60 patients 51 (85.0 %) had received no prior treatment, 4 (6.7 %) had received previous surgery with positive or close margins and 5 (8.3 %) had suffered local recurrence after surgery. Of the tumors 52 (86.7 %) were basal cell carcinoma, 7 (11.7 %) squamous cell carcinoma and 1 (1.7 %) Merkel cell carcinoma. Clinical stage of the 51 previously untreated tumors was 38 T1N0, 12 T2N0 and 1 T3N0. Mean follow-up was 92 months (range 6-253 months). Local control was maintained in 96.7 % of patients. Late effects higher than grade 2 were observed in 3.0 % of cases. Functional and cosmetic outcomes were optimal in 68.4 % of patients. Interstitial brachytherapy for carcinoma of the eyelid can achieve local control, cosmetic and functional results comparable to those of surgery. (orig.)

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

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

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

    DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Mitch, Michael G.; Rivard, Mark J.; Stump, Kurt E.; Thomadsen, Bruce R.; Venselaar, Jack L. M. [Department of Medical Physics and Accredited Dosimetry Calibration Laboratory, University of Wisconsin, Madison, Wisconsin 53706 (United States); Department of Radiation Physics, M. D. Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Oncology, Comprehensive Cancer Center of Nevada, Las Vegas, Nevada 89169 (United States); Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Santa Maria Radiation Oncology Center, Santa Maria, California 93454 (United States); Departments of Medical Physics and Human Oncology, University of Wisconsin, Madison, Wisconsin 53706 (United States); Department of Medical Physics and Engineering, Instituut Verbeeten, 5042 SB Tilburg (Netherlands)

    2011-02-15

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

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

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

  4. Absorbed dose assessment of cardiac and other tissues around the cardiovascular system in brachytherapy with 90Sr/90Y source by Monte Carlo simulation

    Cardiac disease is one of the most important causes of death in the world. Coronary artery stenosis is a very common cardiac disease. Intravascular brachytherapy (IVBT) is one of the radiotherapy methods which have been used recently in coronary artery radiation therapy for the treatment of restenosis. 90Sr/90Y, a beta-emitting source, is a proper option for cardiovascular brachytherapy. In this research, a Monte Carlo simulation was done to calculate dosimetry parameters and effective equivalent doses to the heart and its surrounding tissues during IVBT. The results of this study were compared with the published experimental data and other simulations performed by different programs but with the same source of radiation. A very good agreement was found between results of this work and the published data. An assessment of the risk for cardiac and other sensitive soft tissues surrounding the treated vessel during 90Sr/90Y IVBT was also performed in the study. (authors)

  5. A systematic evaluation of the dose-rate constant determined by photon spectrometry for 21 different models of low-energy photon-emitting brachytherapy sources

    The aim of this study was to perform a systematic comparison of the dose-rate constant (Λ) determined by the photon spectrometry technique (PST) with the consensus value (CONΛ) recommended by the American Association of Physicists in Medicine (AAPM) for 21 low-energy photon-emitting interstitial brachytherapy sources. A total of 63 interstitial brachytherapy sources (21 different models with 3 sources per model) containing either 125I (14 models), 103Pd (6 models) or 131Cs (1 model) were included in this study. A PST described by Chen and Nath (2007 Med. Phys. 34 1412-30) was used to determine the dose-rate constant (PSTΛ) for each source model. Source-dependent variations in PSTΛ were analyzed systematically against the spectral characteristics of the emitted photons and the consensus values recommended by the AAPM brachytherapy subcommittee. The values of PSTΛ for the encapsulated sources of 103Pd, 125I and 131Cs varied from 0.661 to 0.678 cGyh-1 U-1, 0.959 to 1.024 cGyh-1U-1 and 1.066 to 1.073 cGyh-1U-1, respectively. The relative variation in PSTΛ among the six 103Pd source models, caused by variations in photon attenuation and in spatial distributions of radioactivity among the source models, was less than 3%. Greater variations in PSTΛ were observed among the 14 125I source models; the maximum relative difference was over 6%. These variations were caused primarily by the presence of silver in some 125I source models and, to a lesser degree, by the variations in photon attenuation and in spatial distribution of radioactivity among the source models. The presence of silver generates additional fluorescent x-rays with lower photon energies which caused the PSTΛ value to vary from 0.959 to 1.019 cGyh-1U-1 depending on the amount of silver used by a given source model. For those 125I sources that contain no silver, their PSTΛ was less variable and had values within 1% of 1.024 cGyh-1U-1. For the 16 source models that currently have an AAPM recommended

  6. Dosimetric characterization of the GammaClip™169Yb low dose rate permanent implant brachytherapy source for the treatment of nonsmall cell lung cancer postwedge resection

    Purpose: A novel 169Yb low dose rate permanent implant brachytherapy source, the GammaClip™, was developed by Source Production and Equipment Co. (New Orleans, LA) which is designed similar to a surgical staple while delivering therapeutic radiation. In this report, the brachytherapy source was characterized in terms of “Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO” by Perez-Calatayud et al. [Med. Phys. 39, 2904–2929 (2012)] using the updated AAPM Task Group Report No. 43 formalism.Methods: Monte Carlo calculations were performed using Monte Carlo N-Particle 5, version 1.6 in water and air, the in-air photon spectrum filtered to remove photon energies below 10 keV in accordance with TG-43U1 recommendations and previously reviewed 169Yb energy cutoff levels [D. C. Medich, M. A. Tries, and J. M. Munro, “Monte Carlo characterization of an Ytterbium-169 high dose rate brachytherapy source with analysis of statistical uncertainty,” Med. Phys. 33, 163–172 (2006)]. TG-43U1 dosimetric data, including SK, D-dot (r,θ), Λ, gL(r), F(r, θ), φan(r), and φan were calculated along with their statistical uncertainties. Since the source is not axially symmetric, an additional set of calculations were performed to assess the resulting axial anisotropy.Results: The brachytherapy source's dose rate constant was calculated to be (1.22 ± 0.03) cGy h−1 U−1. The uncertainty in the dose to water calculations, D-dot (r,θ), was determined to be 2.5%, dominated by the uncertainties in the cross sections. The anisotropy constant, φan, was calculated to be 0.960 ± 0.011 and was obtained by integrating the anisotropy factor between 1 and 10 cm using a weighting factor proportional to r−2. The radial dose function was calculated at distances between 0.5 and 12 cm, with a maximum value of 1.20 at 5.15 ± 0.03 cm. Radial dose values were fit to a fifth order polynomial and dual exponential

  7. Prostate brachytherapy

    Implant therapy - prostate cancer; Radioactive seed placement; Internal radiation therapy - prostate; High dose radiation (HDR) ... Brachytherapy takes 30 minutes or more, depending on the type of therapy you have. Before the procedure, ...

  8. Determination of surface dose rate of indigenous (32)P patch brachytherapy source by experimental and Monte Carlo methods.

    Kumar, Sudhir; Srinivasan, P; Sharma, S D; Saxena, Sanjay Kumar; Bakshi, A K; Dash, Ashutosh; Babu, D A R; Sharma, D N

    2015-09-01

    Isotope production and Application Division of Bhabha Atomic Research Center developed (32)P patch sources for treatment of superficial tumors. Surface dose rate of a newly developed (32)P patch source of nominal diameter 25 mm was measured experimentally using standard extrapolation ionization chamber and Gafchromic EBT film. Monte Carlo model of the (32)P patch source along with the extrapolation chamber was also developed to estimate the surface dose rates from these sources. The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and radiochromic films are 82.03±4.18 (k=2) and 79.13±2.53 (k=2) respectively. The two values of the surface dose rates measured using the two independent experimental methods are in good agreement to each other within a variation of 3.5%. The surface dose rate to tissue (cGy/min) estimated using the MCNP Monte Carlo code works out to be 77.78±1.16 (k=2). The maximum deviation between the surface dose rates to tissue obtained by Monte Carlo and the extrapolation chamber method is 5.2% whereas the difference between the surface dose rates obtained by radiochromic film measurement and the Monte Carlo simulation is 1.7%. The three values of the surface dose rates of the (32)P patch source obtained by three independent methods are in good agreement to one another within the uncertainties associated with their measurements and calculation. This work has demonstrated that MCNP based electron transport simulations are accurate enough for determining the dosimetry parameters of the indigenously developed (32)P patch sources for contact brachytherapy applications. PMID:26086681

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

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

    2014-02-01

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

  10. New Brachytherapy Standards Paradigm Shift

    The absorbed dose to water rate at short distances in water is the quantity of interest for dosimetry in radiotherapy, but no absorbed dose to water primary standards have been available to date for dosimetry of brachytherapy sources. Currently, the procedures to determine the absorbed dose imparted to the patient in brachytherapy treatments are based on measurements traceable to air kerma standards. These procedures are affected by an uncertainty that is larger than the limit recommended by the IAEA dosimetry protocol (IAEA TRS 398 (2000)). Based on this protocol, the goal for the uncertainty of the dose delivered to the target volume should be within 5% (at the level of one standard deviation) to assure the effectiveness of a radiotherapy treatment. The international protocols for the calibration of brachytherapy gamma ray sources are based on the reference air kerma rate or the air kerma strength. The absorbed dose to water, in water at the reference position around a brachytherapy source is then calculated by applying the formalism of the protocols based on a conversion constant, the dose rate constant Λ, specific for the characteristics and geometry of the brachytherapy source. The determination of this constant relies on Monte Carlo simulations and relative measurements performed with passive dosimeters, and therefore it is typically affected by large uncertainties, larger than 5% (at the level of one standard deviation). The conversion procedure needed for brachytherapy dosimetry is a source of additional uncertainty on the final value of the absorbed dose imparted to the patient. It is due to a lack of metrology standards that makes dosimetry of brachytherapy sources less accurate than dosimetry of external radiation beams produced by 60Co sources and accelerators currently used in external beam radiotherapy. This paper reviews the current developments of absorbed dose to water primary standards for brachytherapy and the rationale for the choice of the

  11. Preliminary results of a phase I/II study of HDR brachytherapy alone for T1/T2 breast cancer

    Purpose: To investigate the feasibility, toxicity, cosmetic outcome, and local control of high-dose-rate (HDR) brachytherapy alone without whole breast external beam irradiation for early-stage breast carcinoma. Methods and Materials: Between June 1997 and August 1999, 32 women diagnosed with a total of 33 AJCC Stage I/II breast carcinomas underwent surgical breast excision and postoperative irradiation using HDR brachytherapy interstitial implantation as part of a multi-institutional clinical Phase I/II protocol. Eligible patients included those with T1, T2, N0, N1 (≤3 nodes positive), and M0 tumors of nonlobular histologic features with negative surgical margins, no extracapsular lymph node extension, and a negative postexcision mammogram. Brachytherapy catheters were placed at the initial excision, reexcision, or either sentinel or full-axillary sampling. Direct visualization, surgical clips, and ultrasound and/or CT scan assisted in the delineation of the target volume, defined as the excision cavity plus a 2-cm margin. High-activity 192Ir (3-10 Ci) was used to deliver 340 cGy/fraction, 2 fractions/d, for 5 consecutive days, to a total dose of 34 Gy to the target volume. Source position and dwell times were calculated using standard volume optimization techniques. Results: The median follow-up of all patients was 33 months, and the mean patient age was 63 years. The mean tumor size was 1.3 cm, and 55% had an extensive intraductal component. Three patients had positive axillary nodes. Two patients experienced moderate perioperative pain that required narcotic analgesics. No peri- or postoperative infections occurred. No wound healing problems and no significant skin reactions related to the implant developed. The Radiation Therapy Oncology Group late radiation morbidity scoring scheme was applied to the entire 33-case cohort. In the assessment of the skin, 30 cases were Grade 0-1 and 3 cases were Grade 2. Subcutaneous toxicity was scored as 11 patients with

  12. Characteristics and locations of sources

    Lahtinen, J.; Poellaenen, R.; Toivonen, H. [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

    1997-12-31

    Ten artificial radiation sources were placed in the terrain in order to test the capability of airborne measuring teams to detect them. One of the sources was a line source, others were point sources (three of them collimated). The radionuclides used in the sources were {sup 60}Co, {sup 137}Cs, {sup 99m}Tc and {sup 192}Ir. The source activities ranged from about 26 MBq (one of the cobalt sources) to 0.56 TBq (iridium). (au).

  13. WE-A-17A-02: BEST IN PHYSICS (THERAPY) - Development of a Calorimeter for the Measurement of the Power Emitted From LDR Brachytherapy Sources

    Purpose: Model-based dose calculation algorithms for brachytherapy sources are designed to compute dose per particle or dose per unit energy leaving the encapsulation of a brachytherapy source. As such, the power leaving the encapsulation of a source, called emitted power (EP), would be a natural source strength metric for these new algorithms. However, no instrument is currently capable of an absolute measurement of EP. A calorimeter operating with a liquid helium thermal sink was designed and constructed to measure the EP of low-dose rate (LDR) I-125 and Pd-103 brachytherapy sources. Methods: Calorimeter design was optimized through thermal and Monte Carlo (MC) modeling. Thermal modeling showed that specific thermal conditions would be necessary for accurate calorimeter measurements. These conditions were experimentally verified. The EP of two LDR I-125 source models was measured. An air-kermastrength (AKS)-to-EP conversion coefficient was determined through MC simulations and applied to well-type ionization chamber measurements of AKS to enable comparison with EP measurements. Results: MCdetermined EP per unit AKS conversion coefficients were source model dependent and are on the order of 0.1 μW/U. The signal-to-noise ratio was a function of source strength, and was 294 for a 0.5 μW source. Measurements were repeatable to within 3.6% for a 0.5 μW source. Initial EP measurements were made with two I-125 source models, a 5.7 U Oncura 6711 and a 2.9 U Best Medical 2301. Model 2301 results agreed with the MC-converted AKS value to within the measurement uncertainty of 4.3% at k=1. The Model 6711 results were systematically high and are under investigation. Conclusion: A calorimeter was designed to provide an absolute measurement of the EP for LDR brachytherapy sources and preliminary EP measurements have been made. This new calorimeter design shows promise of providing a more fundamentally useful source strength standard

  14. Study and parameters survey for iodine-125 source dosimetry to be applied in brachytherapy

    The use of brachytherapy technique with iodine-125 seeds to prostate cancer treatment has been used for decades with good clinical outcomes. To aim the Brazilian population necessities, IPEN-CNEN/SP developed the iodine-125 seed prototype with national technology. The objectives of this work are the development and the study of dosimetric procedures associates with the experimental acquisition of the useful parameters for the iodine-125 dosimetric characterization and to evaluate if the developed procedures, in this work, have the basic conditions to determinate the dosimetric analysis, that are fundamental for clinical procedures. The dosimeters selected for the analysis are the TLD-100 (LiF:Mg,Ti), initially these dosimeters were submitted for two selection steps to choose the dosimeters more reproducible for the dosimetric analysis. The two steps were the selection by the mass of the dosimeters and the reproducibility after four irradiation series in a Cobalt-60 irradiator (CTR-IPEN). Afterwards these steps, the dosimeters were irradiated in linear accelerator with 6 MV energy (Service of Radiotherapy - Hospital Israelita Albert Einstein) to yield the individual calibration factors to each dosimeter. After, the dosimeters were used to the irradiations with iodine-125 seed, 6711 model, (GE-Healthcare). The irradiations and others analysis with iodine-125 seeds yield the useful values for the determination of the parameters suggested by the AAPM (American Association of Physicists in Medicine): constant of dose rate, geometry function, dose radial function and anisotropy function. The results showed good agreement with the values published by the literature, for the same iodine- 125 model, this fact confirms that the realized parameters will be able to be used for the IPEN-CNEN iodine-125 seeds dosimetry and quality control. (author)

  15. Quantification of iodine in porous hydroxyapatite matrices for application as radioactive sources in brachytherapy

    Kássio André Lacerda

    2007-07-01

    Full Text Available In this study, non-radioactive iodine was incorporated in two types of biodegradable hydroxyapatite-based porous matrices (HA and HACL through impregnation process from sodium iodine aqueous solutions with varying concentrations (0.5 and 1.0 mol/L . The results revealed that both systems presented a high capacity of incorporating iodine into their matrices. The quantity of incorporated iodine was measured through Neutron Activation Analysis (NAA. The porous ceramic matrices based on hydroxyapatite demonstrated a great potential for uses in low dose rate (LDR brachytherapy.Materiais cerâmicos porosos à base de compostos de fosfatos de cálcio (CFC vêm sendo estudados e desenvolvidos para várias aplicações biomédicas tais como implantes, sistemas para liberação de drogas e fontes radioativas para braquiterapia. Dois tipos de matrizes porosas biodegradáveis de hidroxiapatita (HA e HACL foram avaliadas em termos da capacidade de incorporação de iodo em suas estruturas. Resultados revelaram que as matrizes porosas a base de hidroxiapatita apresentaram alta capacidade de incorporar iodo em sua estrutura. A quantidade de iodo foi mensurada através da técnica de Análise por Ativação Nêutronica (AAN. As matrizes cerâmicas porosas à base de hidroxiapatita demostraram ter grande potencial para aplicação em braquiterapia de baixa taxa de dose (LDR - Low Dose Rate.

  16. Brachytherapy in vulvar cancer: analysis of 18 patients

    INTRODUCTION: Vulvar cancer is a rather common neoplasm in elderly patients. Surgery, followed eventually by postoperative radiotherapy, is the treatment of choice. The results of exclusive radiotherapy (external beam irradiation and/or brachytherapy) are not well defined and in the recent literature only small series are reported. Radiotherapy however is the only therapeutic option in patients who are not fit for radical surgery. It is thus necessary to review its indications and its modalities. PATIENTS METHODS AND RESULTS: From 1990 to 1994 18 pts with a diagnosis of squamous cell carcinoma of the vulva have been submitted to brachytherapy. Age ranged from 60 to 92 years (mean age 76, 1 ys). 14 pts were treated at diagnosis (11 pts) or for recurrent disease after surgery (3 pts). In 8 of them brachytherapy (total dose 35-45 Gy, dose rate: 0,4-0,78 Gy/h) was preceded by external beam irradiation (Co60 or electron beam, 40-50 Gy to primary and inguinal nodes); 6 pts were treated with brachytherapy alone (58-60 Gy; dose rate 0,44-0,63 Gy/h). 4 pts underwent to brachytherapy alone for local recurrence after surgery and postoperative radiotherapy (total dose 45-60 Gy; dose rate 0,37-0,49 Gy/h). Brachytherapy was always performed with 192 Ir. Plastic tubes (2 to 5 lines) were used for single plane implantation of small exophytic lesions limited to the labia (8 cases); a perineal template (10 cases) was employed in lesions extended to the vaginal mucosa or involving the clitoris or the area of the perineum. (10(14)) pts treated at diagnosis are alive and free from local recurrence after 11-48 mos. 3 of them, treated with brachytherapy alone, have presented a nodal recurrence in the groin after 14, 15 and 27 mos. respectively. All of them are alive and free from disease after surgery and external radiotherapy. None of the pts treated for recurrent disease after surgery + external beam radiotherapy has achieved a local control. CONCLUSION: Brachytherapy alone or

  17. Specification of absorbed dose to water using model-based dose calculation algorithms for treatment planning in brachytherapy

    Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm–10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from 125I, 169Yb and 192Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1–10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies w,med/Dmed is discussed in terms of the cavity size in relation to the size of important cellular targets. Free radicals from DNA bound water of nanometre dimensions contribute to DNA damage and cell killing and may be the most important water compartment in cells implying use of ratios of mass-collision-stopping powers for converting Dmed into Dw,med. (paper)

  18. Study and methodology development for quality control in the production process of iodine-125 radioactive sealed sources applied to brachytherapy

    Today cancer is the second cause of death by disease in several countries, including Brazil. Excluding skin cancer, prostate cancer is the most incident in the population. Prostate tumor can be treated by several ways, including brachytherapy, which consists in introducing sealed radioactive sources (Iodine - 125 seeds) inside the tumor. The target region of treatment receives a high radiation dose, but healthy neighbor tissues receive a significantly reduced radiation dose. The seed is made of a welding sealed titanium capsule, 0.8 mm external diameter and 4.5 mm length, enclosing a 0.5 mm diameter silver wire with Iodine-125 adsorbed. After welded, the seeds have to be submitted to a leak test to prevent any radioactive material release. The aims of this work were: (a) the study of the different leakage test methods applied to radioactive seeds and recommended by the ISO 997820, (b) the choice of the appropriate method and (c) the flowchart determination of the process to be used during the seeds production. The essays exceeded the standards with the use of ultra-sound during immersion and the corresponding benefits to leakage detection. Best results were obtained with the immersion in distilled water at 20 degree C for 24 hours and distilled water at 70 degree C for 30 minutes. These methods will be used during seed production. The process flowchart has all the phases of the leakage tests according to the sequence determined in the experiments. (author)

  19. A dual-plane co-RASOR technique for accurate and rapid tracking and position verification of an Ir-192 source for single fraction HDR brachytherapy

    de Leeuw, Hendrik; Moerland, Marinus A.; van Vulpen, Marco; Seevinck, Peter R.; Bakker, Chris J. G.

    2013-11-01

    Effective high-dose-rate (HDR) treatment requires accurate and independent treatment verification to ensure that the treatment proceeds as prescribed, in particular if a high dose is given, as in single fraction therapy. Contrary to CT imaging and fluoroscopy, MR imaging provides high soft tissue contrast. Conventional MR techniques, however, do not offer the temporal resolution in combination with the 3D spatial resolution required for accurate brachytherapy source localization. We have developed an MR imaging method (center-out RAdial Sampling with Off-Resonance (co-RASOR)) that generates high positive contrast in the geometrical center of field perturbing objects, such as HDR brachytherapy sources. co-RASOR generates high positive contrast in the geometric center of an Ir-192 source by applying a frequency offset to center-out encoded data. To obtain high spatial accuracy in 3D with adequate temporal resolution, two orthogonal center-out encoded 2D images are applied instead of a full 3D acquisition. Its accuracy in 3D is demonstrated by 3D MRI and CT. The 2D images show high positive contrast in the geometric center of non-radioactive Ir-192 sources, with signal intensities up to 160% of the average signal intensity in the surrounding medium. The accuracy with which the center of the Ir-192 source is located by the dual-plane MRI acquisition corresponds closely to the accuracy obtained by 3D MRI and CT imaging. The positive contrast is shown to be obtained in homogeneous and in heterogeneous tissue. The dual-plane MRI technique allows the brachytherapy source to be tracked in 3D with millimeter accuracy with a temporal resolution of approximately 4 s.

  20. Impact of Heterogeneity-Based Dose Calculation Using a Deterministic Grid-Based Boltzmann Equation Solver for Intracavitary Brachytherapy

    Purpose: To investigate the dosimetric impact of the heterogeneity dose calculation Acuros (Transpire Inc., Gig Harbor, WA), a grid-based Boltzmann equation solver (GBBS), for brachytherapy in a cohort of cervical cancer patients. Methods and Materials: The impact of heterogeneities was retrospectively assessed in treatment plans for 26 patients who had previously received 192Ir intracavitary brachytherapy for cervical cancer with computed tomography (CT)/magnetic resonance-compatible tandems and unshielded colpostats. The GBBS models sources, patient boundaries, applicators, and tissue heterogeneities. Multiple GBBS calculations were performed with and without solid model applicator, with and without overriding the patient contour to 1 g/cm3 muscle, and with and without overriding contrast materials to muscle or 2.25 g/cm3 bone. Impact of source and boundary modeling, applicator, tissue heterogeneities, and sensitivity of CT-to-material mapping of contrast were derived from the multiple calculations. American Association of Physicists in Medicine Task Group 43 (TG-43) guidelines and the GBBS were compared for the following clinical dosimetric parameters: Manchester points A and B, International Commission on Radiation Units and Measurements (ICRU) report 38 rectal and bladder points, three and nine o’clock, and D2cm3 to the bladder, rectum, and sigmoid. Results: Points A and B, D2 cm3 bladder, ICRU bladder, and three and nine o’clock were within 5% of TG-43 for all GBBS calculations. The source and boundary and applicator account for most of the differences between the GBBS and TG-43 guidelines. The D2cm3 rectum (n = 3), D2cm3 sigmoid (n = 1), and ICRU rectum (n = 6) had differences of >5% from TG-43 for the worst case incorrect mapping of contrast to bone. Clinical dosimetric parameters were within 5% of TG-43 when rectal and balloon contrast were mapped to bone and radiopaque packing was not overridden. Conclusions: The GBBS has minimal impact on clinical

  1. Radiological protection on interstitial brachytherapy and dose determination and exposure rate of an Ir-192 source through the MCNP-4B

    The present work was carried out in the Neurological Sciences Institute having as objective to determine the dose and the rate of exhibition of the sources of Iridium 192, Iodine 125 and Palladium 103; which are used to carry out implant in the Interstitial Brachytherapy according to the TG43. For it we carry out a theoretical calculation, its are defined in the enter file: the geometry, materials of the problem and the radiation source, etc; in the MCNP-4B Monte Carlo code, considering a punctual source and for the dose determination we simulate thermoluminescent dosemeters (TLD): at 5 cm, 50 cm, 100 cm and 200 cm of the source. Our purpose is to analyze the radioprotection measures that should take into account in this Institute in which are carried out brain biopsies using a Micro mar stereotactic mark, and in a near future with the collaboration of a doctor and a cuban physique seeks to be carried out the Interstitial Brachytherapy technique with sources of Ir-192 for patient with tumors like glioblastoma, astrocytoma, etc. (Author)

  2. Determination of dosimetric characteristics of 125I-103Pd brachytherapy source with Monte-Carlo method

    According to dose parameters calculation formula of seed source recommended by AAPM TG43U1, 125I-103Pd seed source dose parameters calculation formula and a variety of radionuclides composite seed source of dose parameters calculation formula can be obtain. Dose rate constant, radial dose function and anisotropy function of 125I-103Pd composite seed source are calculated by Monte-Carlo method, Empiric equations are obtained for radial dose function and anisotropy function by curve fitting. Comparisons with the relative data recommend by AAPM are performed. For the single source, the deviation of dose rate constant is 0.959 (cGy·h-1·U-1), and with 0.6093% from the AAPM. (authors)

  3. Numerical calculation of relative dose rates from spherical 106Ru beta sources used in ophthalmic brachytherapy

    Eduardo de Paiva

    2015-01-01

    Full Text Available Concave beta sources of 106Ru/106Rh are used in radiotherapy to treat ophthalmic tumors. However, a problem that arises is the difficult determination of absorbed dose distributions around such sources mainly because of the small range of the electrons and the steep dose gradients. In this sense, numerical methods have been developed to calculate the dose distributions around the beta applicators. In this work a simple code in Fortran language is developed to estimate the dose rates along the central axis of 106Ru/106Rh curved plaques by numerical integration of the beta point source function and results are compared with other calculated data.

  4. Numerical calculation of relative dose rates from spherical 106Ru beta sources used in ophthalmic brachytherapy

    de Paiva, Eduardo

    Concave beta sources of 106Ru/106Rh are used in radiotherapy to treat ophthalmic tumors. However, a problem that arises is the difficult determination of absorbed dose distributions around such sources mainly because of the small range of the electrons and the steep dose gradients. In this sense, numerical methods have been developed to calculate the dose distributions around the beta applicators. In this work a simple code in Fortran language is developed to estimate the dose rates along the central axis of 106Ru/106Rh curved plaques by numerical integration of the beta point source function and results are compared with other calculated data.

  5. Preparation and evaluation of various 32P sources for intravascular brachytherapy

    A relatively high per cent of restenoses, being a long-term complication of percutaneous transluminal coronary angioplasty (PTCA), can be significantly reduced by short-range ionizing radiation applied locally, immediately after PTCA. In search for dosimetrically favourable and easy to handle radiation sources for this purpose, we tried a pure β- emitter 32P (t1/2=14.3 days). Ways of preparation of 32 P sources were the following: (1) Neutron activation of 31P layers implanted into metallic surfaces by ionic methods; (2) Conversion coating of metallic surfaces in aqueous solutions containing 32PO43- ions; (3) Direct application of Na2H32 PO4 solutions in the angioplasty balloon. It was shown that: (1) 32 P sources obtained by 31 P ion implantation followed by neutron activation can be useful, but only if activation of the support material by thermal neutrons is negligible; (2) Phosphate layers on stainless steel surface exhibit rather poor adhesion. Similar layers on titanium require further studies; (3) Liquid 32 P sources ensure very good radial dose distribution but only utmost care in filling the balloon can give a reliable activity-dose dependence. Dosimetry of liquid sources, performed in a PMMA phantom by thermoluminescence method showed that 32 P sources of radioactive concentration of 200 MBq/cm3 can deposit therapeutic dose during about 12 min of exposition. TL detectors manufactured for this purpose in our laboratory show very good spatial resolution and can be recommended for similar studies. (author)

  6. A photon spectrometric dose-rate constant determination for the Advantage Pd-103 brachytherapy source

    Purpose: Although several dosimetric characterizations using Monte Carlo simulation and thermoluminescent dosimetry (TLD) have been reported for the new Advantage Pd-103 source (IsoAid, LLC, Port Richey, FL), no AAPM consensus value has been established for the dosimetric parameters of the source. The aim of this work was to perform an additional dose-rate constant (Λ) determination using a recently established photon spectrometry technique (PST) that is independent of the published TLD and Monte Carlo techniques. Methods: Three Model IAPD-103A Advantage Pd-103 sources were used in this study. The relative photon energy spectrum emitted by each source along the transverse axis was measured using a high-resolution germanium spectrometer designed for low-energy photons. For each source, the dose-rate constant was determined from its emitted energy spectrum. The PST-determined dose-rate constant (PSTΛ) was then compared to those determined by TLD (TLDΛ) and Monte Carlo (MCΛ) techniques. A likely consensus Λ value was estimated as the arithmetic mean of the average Λ values determined by each of three different techniques. Results: The average PSTΛ value for the three Advantage sources was found to be (0.676±0.026) cGyh-1 U-1. Intersource variation in PSTΛ was less than 0.01%. The PSTΛ was within 2% of the reported MCΛ values determined by PTRAN, EGSnrc, and MCNP5 codes. It was 3.4% lower than the reported TLDΛ. A likely consensus Λ value was estimated to be (0.688±0.026) cGyh-1 U-1, similar to the AAPM consensus values recommended currently for the Theragenics (Buford, GA) Model 200 (0.686±0.033) cGyh-1 U-1, the NASI (Chatsworth, CA) Model MED3633 (0.688±0.033) cGyh-1 U-1, and the Best Medical (Springfield, VA) Model 2335 (0.685±0.033) cGyh-1 U-1103Pd sources. Conclusions: An independent Λ determination has been performed for the Advantage Pd-103 source. The PSTΛ obtained in this work provides additional information needed for establishing a more

  7. Brachytherapy for the prevention of neointimal hyperplasia in the canine inferior vena cava after stent placement

    Isota, Masayuki; Kaminou, Toshio; Sakai, Yukimasa; Nakamura, Kenji; Yamada, Ryusaku [Osaka City Univ. (Japan). Medical School

    2002-06-01

    The aim of this study was to evaluate the efficacy of brachytherapy for preventing neointimal hyperplasia in the inferior vena cava (IVC) after stent placement. Sixteen beagles underwent Z-stent placement in the IVC and the aorta. For 8 of 16 beagles, irradiation (15 Gy) was delivered endoluminally to the stented segments of each vessel immediately after stent placement using the {sup 192}Ir. All animals were sacrificed after 6 weeks for morphometric and histopathologic examination. Morphometrically, neointimal thickness in the IVC of the radiation group was significantly decreased compared with the control group as well as that in the aorta (p<0.05). Histopathologic findings showed the neointima in the IVC of the control group contained markedly organization of thrombus and neovascularization though that in the IVC of the radiation group consisted mainly of smooth muscle cells without organization of thrombus and neovascularization. From these data intravenous irradiation may prevent clinical restenosis after stent placement. (author)

  8. Impact of the differential fluence distribution of brachytherapy sources on the spectroscopic dose-rate constant

    Malin, Martha J.; Bartol, Laura J.; DeWerd, Larry A., E-mail: mmalin@wisc.edu, E-mail: ladewerd@wisc.edu [Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin 53705 (United States)

    2015-05-15

    Purpose: To investigate why dose-rate constants for {sup 125}I and {sup 103}Pd seeds computed using the spectroscopic technique, Λ{sub spec}, differ from those computed with standard Monte Carlo (MC) techniques. A potential cause of these discrepancies is the spectroscopic technique’s use of approximations of the true fluence distribution leaving the source, φ{sub full}. In particular, the fluence distribution used in the spectroscopic technique, φ{sub spec}, approximates the spatial, angular, and energy distributions of φ{sub full}. This work quantified the extent to which each of these approximations affects the accuracy of Λ{sub spec}. Additionally, this study investigated how the simplified water-only model used in the spectroscopic technique impacts the accuracy of Λ{sub spec}. Methods: Dose-rate constants as described in the AAPM TG-43U1 report, Λ{sub full}, were computed with MC simulations using the full source geometry for each of 14 different {sup 125}I and 6 different {sup 103}Pd source models. In addition, the spectrum emitted along the perpendicular bisector of each source was simulated in vacuum using the full source model and used to compute Λ{sub spec}. Λ{sub spec} was compared to Λ{sub full} to verify the discrepancy reported by Rodriguez and Rogers. Using MC simulations, a phase space of the fluence leaving the encapsulation of each full source model was created. The spatial and angular distributions of φ{sub full} were extracted from the phase spaces and were qualitatively compared to those used by φ{sub spec}. Additionally, each phase space was modified to reflect one of the approximated distributions (spatial, angular, or energy) used by φ{sub spec}. The dose-rate constant resulting from using approximated distribution i, Λ{sub approx,i}, was computed using the modified phase space and compared to Λ{sub full}. For each source, this process was repeated for each approximation in order to determine which approximations used in

  9. Low dose rate 137Cs Brachytherapy source calibration with farmer type ionisation chamber and specialised fabricated jig in Korle-Bu Teaching Hospital

    An important part of a general quality assurance (QA) program for brachytherapy dosimetry is the source calibration because wide ranges of uncertainties are quoted by manufactures. This research is aimed at calibrating LDR 137Cs brachytherapy source in the Korle-Bu Teaching Hospital by multiple-distance air kerma measurement technique using a specialized designed jig and a calibrated therapy ionization chamber. Specialized jig was fabricated with source holder positions and ionization chamber positions on the jig. Farmer type ionization chamber of volume 0.6cm3 was used with and without build up cap. The results were validated using well type ionization chamber on channels on 1 and 5 taking into account decay correction. Air Kerma rates were determined at multiple distances between 8cm to 12cm from measured charges recorded by Max 4000 electrometer. The scatter dose relationship described by Ezzell [1992] was used to determine scattered radiation. The analytical method of determining air kerma calibration factor of 137Cs described by Sharma et.al [2011] was used to determine beam quality correction factor for the 137Cs. Beam attenuation was determined. Experimental data were compared with manufacturer's quoted source strength for verification. Well type ionization chamber results and experimental results on channel V1 and V5 deviated by 2.39% and 1.58% respectively. Experimental data deviated by 4.73% and 1.24% from theoretical data on channels V1 and V5 respectively. The mean of the experimental data deviated from the theoretical data by ±3.1% and from the well type measurements data by ±1.98%. The well type chamber results compared well with the experimental data. This is an indication that the method used for source calibration is a reliable alternative method of source calibration. The method used in this work has proven to be an efficient way of determining the actual source strength of the LDR brachytherapy 137Cs source in Korle-Bu Radiotherapy Centre

  10. Definition study of the project Dosimetry Brachytherapy

    The purpose of the research project Dosimetry Brachytherapy is the standardization of calibration methods and quality control procedures used for Brachytherapy sources. Proposals to develop measurement standards and methods for calibrating these sources are presented. Brachytherapy sources will be calibrated in terms of reference airkerma rate or in terms of absorbed dose in water. Therefore, in this project, special attention will be given to the in-phantom measurement method described by Meertens and the use of re-entrant ionisation chambers as transfer standards. In this report, a workplan and time schedule is included. (author). 19 refs.; 1 fig

  11. Evaluation of a lithium formate EPR dosimetry system for dose measurements around Ir-192 brachytherapy sources

    Antonovic, Laura; Gustafsson, Håkan; Alm Carlsson, Gudrun; Carlsson Tedgren, Åsa

    2009-01-01

    A dosimetry system using lithium formate monohydrate (HCO2Li center dot H2O) as detector material and electron paramagnetic resonance (EPR) spectroscopy for readout has been used to measure absorbed dose distributions around clinical Ir-192 sources. Cylindrical tablets with diameter of 4.5 mm, height of 4.8 mm, and density of 1.26 g/cm(3) were manufactured. Homogeneity test and calibration of the dosimeters were performed in a 6 MV photon beam. Ir-192 irradiations were performed in a PMMA pha...

  12. SU-F-19A-04: Dosimetric Evaluation of a Novel CT/MR Compatible Fletcher Applicator for Intracavitary Brachytherapy of the Cervix Uteri

    Gifford, K; Han, T [UT MD Anderson Cancer Center, Houston, TX (United States); Mourtada, F [Christiana Care Hospital, Newark, DE (United States); Eifel, P [The UT MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-15

    Purpose: To validate a Monte Carlo model and evaluate the dosimetric capabilities of a novel commercial CT/MR compatible Fletcher applicator for cervical cancer brachytherapy. Methods: MCNPX 2.7.0 was used to model the Fletcher CT/MR shielded applicator (FA) and 192Ir HDR source. Energy deposition was calculated with a track length estimator modified by an energy-dependent heating function. A high density polystyrene phantom was constructed with three film pockets for validation of the MCNPX model. Three planes of data were calculated with the MCNPX model corresponding to the three film planes in phantom. The planes were located 1 cm from the most anterior, posterior, and medial extents of the FA right ovoid. Unshielded distributions were calculated by modeling the shielded cells as air instead of the tungsten alloy. A third order polynomial fit to the OD to dose curve was used to convert OD of the three film planes to dose. Each film and MCNPX plane dose distribution was normalized to a point 2 cm from the center of the film plane and in a region of low dose gradient. MCNPX and film were overlaid and compared with a distance-to-agreement criterion of (±2%/±2mm). Shielded and unshielded distributions were overlaid and a percent shielded plot was created. Results: 85.2%, 97.1%, and 96.6% of the MCNPX points passed the (±2%/±2mm) criterion respectively for the anterior, lateral, and posterior film comparison planes. A majority of the points in the anterior plane that exceeded the DTA criterion were either along edges of where the film was cut or near the terminal edges of the film. The percent shielded matrices indicated that the maximum % shielding was 50%. Conclusion: These data confirm the validity of the FA Monte Carlo model. The FA ovoid can shield up to 50% of the dose in the anteroposterior direction.

  13. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation; Comparacao da dose absorvida no tratamento do cancer ginecologico por braquiterapia de alta taxa de dose utilizando o planejamento convencional do tratamento e simulacao de Monte Carlo

    Silva, Aneli Oliveira da

    2010-07-01

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of {sup 192}Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results

  14. Dose distribution in water for monoenergetic photon point sources in the energy range of interest in brachytherapy: Monte Carlo simulations with PENELOPE and GEANT4

    Almansa, J F; Anguiano, M; Guerrero, R; Lallena, A M; Al-Dweri, Feras M.O.; Almansa, Julio F.; Guerrero, Rafael

    2006-01-01

    Monte Carlo calculations using the codes PENELOPE and GEANT4 have been performed to characterize the dosimetric properties of monoenergetic photon point sources in water. The dose rate in water has been calculated for energies of interest in brachytherapy, ranging between 10 keV and 2 MeV. A comparison of the results obtained using the two codes with the available data calculated with other Monte Carlo codes is carried out. A chi2-like statistical test is proposed for these comparisons. PENELOPE and GEANT4 show a reasonable agreement for all energies analyzed and distances to the source larger than 1 cm. Significant differences are found at distances from the source up to 1 cm. A similar situation occurs between PENELOPE and EGS4.

  15. Clinical outcome of high-dose-rate interstitial brachytherapy in patients with oral cavity cancer

    Lee, Sung Uk; Cho, Kwan Ho; Moon, Sung Ho; Choi, Sung Weon; Park, Joo Yong; Yun, Tak; Lee, Sang Hyun; Lim, Young Kyung; Jeong, Chi Young [National Cancer Center, Goyang (Korea, Republic of)

    2014-12-15

    To evaluate the clinical outcome of high-dose-rate (HDR) interstitial brachytherapy (IBT) in patients with oral cavity cancer. Sixteen patients with oral cavity cancer treated with HDR remote-control afterloading brachytherapy using 192Ir between 2001 and 2013 were analyzed retrospectively. Brachytherapy was administered in 11 patients as the primary treatment and in five patients as salvage treatment for recurrence after the initial surgery. In 12 patients, external beam radiotherapy (50-55 Gy/25 fractions) was combined with IBT of 21 Gy/7 fractions. In addition, IBT was administered as the sole treatment in three patients with a total dose of 50 Gy/10 fractions and as postoperative adjuvant treatment in one patient with a total of 35 Gy/7 fractions. The 5-year overall survival of the entire group was 70%. The actuarial local control rate after 3 years was 84%. All five recurrent cases after initial surgery were successfully salvaged using IBT +/- external beam radiotherapy. Two patients developed local recurrence at 3 and 5 months, respectively, after IBT. The acute complications were acceptable (< or =grade 2). Three patients developed major late complications, such as radio-osteonecrosis, in which one patient was treated by conservative therapy and two required surgical intervention. HDR IBT for oral cavity cancer was effective and acceptable in diverse clinical settings, such as in the cases of primary or salvage treatment.

  16. Clinical outcome of high-dose-rate interstitial brachytherapy in patients with oral cavity cancer

    To evaluate the clinical outcome of high-dose-rate (HDR) interstitial brachytherapy (IBT) in patients with oral cavity cancer. Sixteen patients with oral cavity cancer treated with HDR remote-control afterloading brachytherapy using 192Ir between 2001 and 2013 were analyzed retrospectively. Brachytherapy was administered in 11 patients as the primary treatment and in five patients as salvage treatment for recurrence after the initial surgery. In 12 patients, external beam radiotherapy (50-55 Gy/25 fractions) was combined with IBT of 21 Gy/7 fractions. In addition, IBT was administered as the sole treatment in three patients with a total dose of 50 Gy/10 fractions and as postoperative adjuvant treatment in one patient with a total of 35 Gy/7 fractions. The 5-year overall survival of the entire group was 70%. The actuarial local control rate after 3 years was 84%. All five recurrent cases after initial surgery were successfully salvaged using IBT +/- external beam radiotherapy. Two patients developed local recurrence at 3 and 5 months, respectively, after IBT. The acute complications were acceptable (< or =grade 2). Three patients developed major late complications, such as radio-osteonecrosis, in which one patient was treated by conservative therapy and two required surgical intervention. HDR IBT for oral cavity cancer was effective and acceptable in diverse clinical settings, such as in the cases of primary or salvage treatment.

  17. Interstitial prostate brachytherapy. LDR-PDR-HDR

    The first comprehensive overview of interstitial brachytherapy for the management of local or locally advanced prostate cancer. Written by an interdisciplinary team who have been responsible for the successful GEC-ESTRO/EAU Teaching Course. Discusses in detail patient selection, the results of different methods, the role of imaging, and medical physics issues. Prostate brachytherapy has been the subject of heated debate among surgeons and the proponents of the various brachytherapy methods. This very first interdisciplinary book on the subject provides a comprehensive overview of innovations in low dose rate (LDR), high dose rate (HDR), and pulsed dose rate (PDR) interstitial brachytherapy for the management of local or locally advanced prostate cancer. In addition to detailed chapters on patient selection and the use of imaging in diagnostics, treatment guidance, and implantation control, background chapters are included on related medical physics issues such as treatment planning and quality assurance. The results obtained with the different treatment options and the difficult task of salvage treatment are fully discussed. All chapters have been written by internationally recognized experts in their fields who for more than a decade have formed the teaching staff responsible for the successful GEC-ESTRO/EAU Prostate Brachytherapy Teaching Course. This book will be invaluable in informing residents and others of the scientific background and potential of modern prostate brachytherapy. It will also prove a useful source of up-to-date information for those who specialize in prostate brachytherapy or intend to start an interstitial brachytherapy service.

  18. Combined transperineal radiofrequency (RF) interstitial hyperthermia and brachytherapy for localized prostate cancer (PC)

    Hyperthermia has been used effectively as a radiation sensitizer. Interstitial hyperthermoradiotherapy has been therefore utilized as a minimal invasive therapy in attempts to improve local tumor control for various cancers, but not for urological cancer. The purpose of this study was to investigate the safety and feasibility of transperineal hyperthermoradiotherapy for localized PC. Based on our basic study of hyperthermoradiotherapy, we devised the procedure of combined transperineal RF interstitial hyperthermia and brachytherapy for localized prostate cancer. Two patients with localized PC underwent transperineal RF interstitial hyperthermia combined with brachytherapy operation the 192-Ir remote after-loading system (RALS). Under transrectal ultrasound guidance, a total number of 12-18 stainless steel needles for 192-Ir RALS were implanted into the prostatic gland and seminal vesicles (SV) in an optimized pattern. Eight of the needles were used as electrodes for hyperthermia, and were electrically insultated using the vinyl catheter along the length of the subdermal fatty tissue to protect from overheating. Three other needles were utilized for continuous temperature mapping in the prostate. Rectal temperature was also monitored. Total radiation doses of 70 Gy to the prostate and SV were planned as a combination of brachytherapy (24 Gy/4 fraction) and external irradiation using a four-field box technique (46 Gy/23 fraction). Hyperthermic treatment (goal of 42 to 43 deg C for 60 minutes) was performed twice following the 1st and 4th brachytherapy at an interval of more than 48 hours for the recovery of cancer cells from thermotolerance. Both patients reached the treatment goal of all intraprostatic temperatures >43.0 deg C, which was considered favorable for hyperthermia, and the rectal temperatures of both patients remained <38 deg C during hyperthermia. In serial PSA measurements of both patients, serum PSA was less than 1.0 ng/ml within 3 months and has since

  19. Combined transperineal radiofrequency (RF) interstitial hyperthermia and brachytherapy for localized prostate cancer (PC)

    Urakami, Shinji; Gonda, Nobuko; Kikuno, Nobuyuki [Shimane Medical Univ., Izumo (Japan)] (and others)

    2001-05-01

    Hyperthermia has been used effectively as a radiation sensitizer. Interstitial hyperthermoradiotherapy has been therefore utilized as a minimal invasive therapy in attempts to improve local tumor control for various cancers, but not for urological cancer. The purpose of this study was to investigate the safety and feasibility of transperineal hyperthermoradiotherapy for localized PC. Based on our basic study of hyperthermoradiotherapy, we devised the procedure of combined transperineal RF interstitial hyperthermia and brachytherapy for localized prostate cancer. Two patients with localized PC underwent transperineal RF interstitial hyperthermia combined with brachytherapy operation the 192-Ir remote after-loading system (RALS). Under transrectal ultrasound guidance, a total number of 12-18 stainless steel needles for 192-Ir RALS were implanted into the prostatic gland and seminal vesicles (SV) in an optimized pattern. Eight of the needles were used as electrodes for hyperthermia, and were electrically insultated using the vinyl catheter along the length of the subdermal fatty tissue to protect from overheating. Three other needles were utilized for continuous temperature mapping in the prostate. Rectal temperature was also monitored. Total radiation doses of 70 Gy to the prostate and SV were planned as a combination of brachytherapy (24 Gy/4 fraction) and external irradiation using a four-field box technique (46 Gy/23 fraction). Hyperthermic treatment (goal of 42 to 43 deg C for 60 minutes) was performed twice following the 1st and 4th brachytherapy at an interval of more than 48 hours for the recovery of cancer cells from thermotolerance. Both patients reached the treatment goal of all intraprostatic temperatures >43.0 deg C, which was considered favorable for hyperthermia, and the rectal temperatures of both patients remained <38 deg C during hyperthermia. In serial PSA measurements of both patients, serum PSA was less than 1.0 ng/ml within 3 months and has since

  20. Brachytherapy applications and techniques

    Devlin, Phillip M

    2015-01-01

    Written by the foremost experts in the field, this volume is a comprehensive text and practical reference on contemporary brachytherapy. The book provides detailed, site-specific information on applications and techniques of brachytherapy in the head and neck, central nervous system, breast, thorax, gastrointestinal tract, and genitourinary tract, as well as on gynecologic brachytherapy, low dose rate and high dose rate sarcoma brachytherapy, vascular brachytherapy, and pediatric applications. The book thoroughly describes and compares the four major techniques used in brachytherapy-intraca

  1. Determination of the Sensibility Factors for TLD-100 Powder on the Energy of X-Ray of 50, 250 kVp; 192Ir, 137Cs and 60Co

    TLD-100 powder is calibrated in terms of absorbed dose to water Dw, using the protocols AAPM TG61, AAPM TG43 and IAEA-TRS 398, for the energy of RX 50, 250 kVp, 137Cs and 60Co respectively. The calibration curves, TLD Response R versus Dw, are fitted by weighted least square by a quadratic polynomials; which are validated with the lack of fit and the Anderson-Darling normality test. The slope of these curves corresponds to the sensibility factor: Fs R/DW, [Fs] = nC Gy-1. The expanded uncertainties U's for these factors are obtained from the ANOVA tables. Later, the Fs' values are interpolated using the effective energy hvefec for the 192Ir. The SSDL sent a set of capsules with powder TLD-100 for two Hospitals. These irradiated them a nominal dose of Dw = 2 Gy. The results determined at SSDL are: for the Hospital A the Dw is overestimated in order to 4.8% and the Hospital B underestimates it in the range from -1.4% to -17.5%

  2. Use of Monte Carlo Methods in brachytherapy

    The Monte Carlo method has become a fundamental tool for brachytherapy dosimetry mainly because no difficulties associated with experimental dosimetry. In brachytherapy the main handicap of experimental dosimetry is the high dose gradient near the present sources making small uncertainties in the positioning of the detectors lead to large uncertainties in the dose. This presentation will review mainly the procedure for calculating dose distributions around a fountain using the Monte Carlo method showing the difficulties inherent in these calculations. In addition we will briefly review other applications of the method of Monte Carlo in brachytherapy dosimetry, as its use in advanced calculation algorithms, calculating barriers or obtaining dose applicators around. (Author)

  3. Study and development of methodology for radioactive iodine fixation in polymeric substrate for manufacturing sources used in brachytherapy

    According global estimates of Globocan 2012 project of the International Agency for Research of Cancer, of the World Health Organization, there were 14,1 million new cases of cancer and a total of 8,2 million deaths from cancer. Also show that in 2030, the overall load will be 21,4 million new cases and 13,2 million cancer deaths. One of the prostate cancer therapy is brachytherapy, used in early and middle stages of the disease. It is made with the introduction of seeds with radioactive material within the tumor or in nearby regions, affecting the minimum surrounding tissues. The aim of this work is the study and developing the deposition of radioactive iodine on the polymeric substrate method, and an analysis relating the efficiency of the method to implementation in the laboratory of brachytherapy from IPEN. Iodine-125 is adsorbed on an epoxy resin solution. The objective of this study is to offer a new proposal for seeds. The results will give the data for the radiation protection and the procedures for radioactive waste management

  4. Intra coronary brachytherapy

    Despite the initial promise of vasculopathy intervention restenosis- a consequence of the (normal) would healing process-has emerged as a major problem. Angiographic restenosis has been reported in 40-60% of patients after successful P TCA. The basic mechanism of restenosis, (acute recoil, negative remodeling and neo intimal hyperplasia), are only partially counteracted by endovascular prosthetic devices (s tents). The rate of in-s tent restenosis, which is primarily caused by neo intimal hyperplasia due to the (micro) trauma of the arterial wall by the s tent struts, has been reduced to 18-32%. Ionizing (beta or gamma) radiations has been established as a potent treatment for malignant disorders. In recent years, there has also been increasing interest among clinicians in the management of benign lesions with radiation. Over the past several years, there has been a growing body of evidence that endovascular brachytherapy has a major impact on the biology of the restenosis. It must be underlined that understanding the biology and pathophysiology of restenosis and assessing various treatment options should preferably be a team effort, with the three gracesbeing interventional cardiologist, nuclear oncologist, and industrial partners. The vast amount of data in over 20000 patients from a wide range of randomized controlled trials, has shown that brachytherapy is the only effective treatment for in-s tent restenosis. We are learning more and more about how to improve brachytherapy. While the new coated s tents that we heard about today is fascinating and extremely promising, brachytherapy still has a very important place in difficult patients, such as those with total occlusions, osti al lesions, left main lesions, multivessel disease and diabetes. Regarding to above mentioned tips, we (a research team work, in the Nuclear Research Center Of the Atomic Energy Organization Of Iran), focused on synthesis and preparation of radioactive materials for use in I c-B T. We

  5. Influence of radioactive sources discretization in the Monte Carlo computational simulations of brachytherapy procedures: a case study on the procedures for treatment of prostate cancer; Influencia da discretizacao das fontes radioativas nas simulacoes computacionais Monte Carlo de procedimentos de braquiterapia: um estudo de caso sobre os procedimentos para tratamento do cancer de prostata

    Barbosa, Antonio Konrado de Santana; Vieira, Jose Wilson [Instituto Federal de Educacao, Ciencia e Tecnologia (IFPE), Recife, PE (Brazil); Costa, Kleber Souza Silva [Faculdade Integrada de Pernambuco (FACIPE), Recife, PE (Brazil); Lima, Fernando Roberto de Andrade, E-mail: falima@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2011-07-01

    Radiotherapy computational simulation procedures using Monte Carlo (MC) methods have shown to be increasingly important to the improvement of cancer fighting strategies. One of the biases in this practice is the discretization of the radioactive source in brachytherapy simulations, which often do not match with a real situation. This study had the aim to identify and to measure the influence of radioactive sources discretization in brachytherapy MC simulations when compared to those that do not present discretization, using prostate brachytherapy with Iodine-125 radionuclide as model. Simulations were carried out with 108 events with both types of sources to compare them using EGSnrc code associated to MASH phantom in orthostatic and supine positions with some anatomic adaptations. Significant alterations were found, especially regarding bladder, rectum and the prostate itself. It can be concluded that there is a need to discretized sources in brachytherapy simulations to ensure its representativeness. (author)

  6. HDR endobronchial brachytherapy

    Introduction: This is a restrospective study to review the palliation rate, survival rate and complications of high dose rate (HDR) endobronchial brachytherapy in the treatment of airway obstruction of recurrent lung cancer or metastasis. Material and method: Between september 1992 and may 1995 it has been treated forty (40) patients with endobronchial lesions. 38 patients with unique endobronchial lesion and 2 patients with double lesions. 32 had primary lung carcinoma: 27 with epidermoid carcinoma (1 bilateral), 2 with adenocarcinoma, 1 with small cell carcinoma, 1 with undifferentiated carcinoma and 1 with primary double (adenocarcinoma and large cell carcinoma). 8 patients had endobronchial metastasis: 2 hypernefroma, 3 breast carcinoma, 1 colon cancer, 1 seminoma and 1 Ewing sarcoma. 33 patients were male (82.5%) and 7 female (17.5%). The treatment was carried out in three weekly fractions with a dose of 750 cGy per fraction at 1 cm from the source. An afterloaded equipment was used (microselectron HDR). The most frequent sites were: right main stem bronchus 9 patients (22.5%), left main stem bronchus 7 patients (17.5%), and right middle bronchus 5 patients (12.5%). Results and discussion: The endoscopic global response assessed after three weeks was of 70%. The symptomatic response was 95% hemoptysis control, 87% dysnea control, 80% obstructive pneumonia control and 70% cough control. The minimum follow up was one year. There were three cases of massive hemoptysis and three patients developed local recurrence (one received a second brachytherapy treatment). Conclusion: HDR brachytherapy offers an excellent long term palliation for any of the obstructing symptoms, being effective in more than 70% in patients with recurrence lung primary cancer or endobronchial metastasis with a low complication rate

  7. Evolution of different reaction methods resulting in the formation of AgI125 for use in brachytherapy sources

    Prostate cancer represents about 10% of all cases of cancer in the world. Brachytherapy has been extensively used in the early and intermediate stages of the illness. The radiotherapy method reduces the damage probability to surrounding healthy tissues. The present study compares several deposition methods of iodine-125 on silver substrate (seed core), in order to choose the most suitable one to be implemented at IPEN. Four methods were selected: method 1 (assay based on electrodeposition) which presented efficiency of 65.16%; method 2 (assay based on chemical reactions, developed by David Kubiatowicz) which presented efficiency of 70.80%; method 3 (chemical reaction based on the methodology developed by Dr. Maria Elisa Rostelato) which presented efficiency of 55.80%; new method developed by IPEN with 90.5% efficiency. Based on the results, the new method is the suggested one to be implemented. (authors)

  8. A revised dosimetric characterization of the model S700 electronic brachytherapy source containing an anode-centering plastic insert and other components not included in the 2006 model

    Hiatt, Jessica R. [Department of Radiation Oncology, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903 (United States); Davis, Stephen D. [Department of Medical Physics, McGill University Health Centre, Montreal, Quebec H3G 1A4 (Canada); Rivard, Mark J., E-mail: mark.j.rivard@gmail.com [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

    2015-06-15

    Purpose: The model S700 Axxent electronic brachytherapy source by Xoft, Inc., was characterized by Rivard et al. in 2006. Since then, the source design was modified to include a new insert at the source tip. Current study objectives were to establish an accurate source model for simulation purposes, dosimetrically characterize the new source and obtain its TG-43 brachytherapy dosimetry parameters, and determine dose differences between the original simulation model and the current model S700 source design. Methods: Design information from measurements of dissected model S700 sources and from vendor-supplied CAD drawings was used to aid establishment of an updated Monte Carlo source model, which included the complex-shaped plastic source-centering insert intended to promote water flow for cooling the source anode. These data were used to create a model for subsequent radiation transport simulations in a water phantom. Compared to the 2006 simulation geometry, the influence of volume averaging close to the source was substantially reduced. A track-length estimator was used to evaluate collision kerma as a function of radial distance and polar angle for determination of TG-43 dosimetry parameters. Results for the 50 kV source were determined every 0.1 cm from 0.3 to 15 cm and every 1° from 0° to 180°. Photon spectra in water with 0.1 keV resolution were also obtained from 0.5 to 15 cm and polar angles from 0° to 165°. Simulations were run for 10{sup 10} histories, resulting in statistical uncertainties on the transverse plane of 0.04% at r = 1 cm and 0.06% at r = 5 cm. Results: The dose-rate distribution ratio for the model S700 source as compared to the 2006 model exceeded unity by more than 5% for roughly one quarter of the solid angle surrounding the source, i.e., θ ≥ 120°. The radial dose function diminished in a similar manner as for an {sup 125}I seed, with values of 1.434, 0.636, 0.283, and 0.0975 at 0.5, 2, 5, and 10 cm, respectively. The radial dose

  9. SU-C-16A-01: In Vivo Source Position Verification in High Dose Rate (HDR) Prostate Brachytherapy Using a Flat Panel Imager: Initial Clinical Experience

    Purpose: We report our initial clinical experience with a novel position-sensitive source-tracking system based on a flat panel imager. The system has been trialled with 4 prostate HDR brachytherapy patients (8 treatment fractions) in this initial study. Methods: The flat panel imaging system was mounted under a customised carbon fibre couch top assembly (Figure 1). Three gold fiducial markers were implanted into the prostate of each patient at the time of catheter placement. X-ray dwell position markers were inserted into three catheters and a radiograph acquired to locate the implant relative to the imaging device. During treatment, as the HDR source dwells were delivered, images were acquired and processed to determine the position of the source in the patient. Source positions measured by the imaging device were compared to the treatment plan for verification of treatment delivery. Results: Measured dwell positions provided verification of relative dwell spacing within and between catheters, in the coronal plane. Measurements were typically within 2.0mm (0.2mm – 3.3mm, s.d. 0.8mm) of the planned positions over 60 dwells (Figure 2). Discrimination between larger dwell intervals and catheter differentiation were clear. This confirms important delivery attributes such as correct transfer tube connection, source step size, relative catheter positions and therefore overall correct plan selection and delivery. The fiducial markers, visible on the radiograph, provided verification of treatment delivery to the correct anatomical location. The absolute position of the dwells was determined by comparing the measured dwell positions with the x-ray markers from the radiograph, validating the programmed treatment indexer length. The total impact on procedure time was less than 5 minutes. Conclusion: The novel, noninvasive HDR brachytherapy treatment verification system was used clinically with minor impact on workflow. The system allows verification of correct treatment

  10. The American Brachytherapy Society recommendations for low-dose-rate brachytherapy for carcinoma of the cervix

    Purpose: This report presents guidelines for using low-dose-rate (LDR) brachytherapy in the management of patients with cervical cancer. Methods: Members of the American Brachytherapy Society (ABS) with expertise in LDR brachytherapy for cervical cancer performed a literature review, supplemented by their clinical experience, to formulate guidelines for LDR brachytherapy of cervical cancer. Results: The ABS strongly recommends that radiation treatment for cervical carcinoma (with or without chemotherapy) should include brachytherapy as a component. Precise applicator placement is essential for improved local control and reduced morbidity. The outcome of brachytherapy depends, in part, on the skill of the brachytherapist. Doses given by external beam radiotherapy and brachytherapy depend upon the initial volume of disease, the ability to displace the bladder and rectum, the degree of tumor regression during pelvic irradiation, and institutional practice. The ABS recognizes that intracavitary brachytherapy is the standard technique for brachytherapy for cervical carcinoma. Interstitial brachytherapy should be considered for patients with disease that cannot be optimally encompassed by intracavitary brachytherapy. The ABS recommends completion of treatment within 8 weeks, when possible. Prolonging total treatment duration can adversely affect local control and survival. Recommendations are made for definitive and postoperative therapy after hysterectomy. Although recognizing that many efficacious LDR dose schedules exist, the ABS presents suggested dose and fractionation schemes for combining external beam radiotherapy with LDR brachytherapy for each stage of disease. The dose prescription point (point A) is defined for intracavitary insertions. Dose rates of 0.50 to 0.65 Gy/h are suggested for intracavitary brachytherapy. Dose rates of 0.50 to 0.70 Gy/h to the periphery of the implant are suggested for interstitial implant. Use of differential source activity or

  11. The role of brachytherapy in radiation and isotopes centre of Khartoum (RICK)

    Ali, A M

    2000-01-01

    As there are many efforts devoted in order to manage the cancer, here the researcher handle one of these efforts that play a major part in treating the cancer internationally, it is a brachytherapy system. Brachytherapy was carried out mostly with radium sources, but recently some artificial sources are incorporated in this mode of treatment such as Cs-137, Ir-192, Au-198, P-32, Sr-90 and I-125. The research cover history of brachytherapy and radioactive sources used in, techniques of implementation, radiation protection and methods of brachytherapy dose calculation, as well as brachytherapy in radiation and isotopes centre in Khartoum.

  12. Comprehensive brachytherapy physical and clinical aspects

    Baltas, Dimos; Meigooni, Ali S; Hoskin, Peter J

    2013-01-01

    Modern brachytherapy is one of the most important oncological treatment modalities requiring an integrated approach that utilizes new technologies, advanced clinical imaging facilities, and a thorough understanding of the radiobiological effects on different tissues, the principles of physics, dosimetry techniques and protocols, and clinical expertise. A complete overview of the field, Comprehensive Brachytherapy: Physical and Clinical Aspects is a landmark publication, presenting a detailed account of the underlying physics, design, and implementation of the techniques, along with practical guidance for practitioners. Bridging the gap between research and application, this single source brings together the technological basis, radiation dosimetry, quality assurance, and fundamentals of brachytherapy. In addition, it presents discussion of the most recent clinical practice in brachytherapy including prostate, gynecology, breast, and other clinical treatment sites. Along with exploring new clinical protocols, ...

  13. Image guided Brachytherapy: The paradigm of Gynecologic and Partial Breast HDR Brachytherapy

    Diamantopoulos, S.; Kantemiris, I.; Konidari, A.; Zaverdinos, P.

    2015-09-01

    High dose rate (HDR) brachytherapy uses high strength radioactive sources and temporary interstitial implants to conform the dose to target and minimize the treatment time. The advances of imaging technology enable accurate reconstruction of the implant and exact delineation of high-risk CTV and the surrounding critical structures. Furthermore, with sophisticated treatment planning systems, applicator devices and stepping source afterloaders, brachytherapy evolved to a more precise, safe and individualized treatment. At the Radiation Oncology Department of Metropolitan Hospital Athens, MRI guided HDR gynecologic (GYN) brachytherapy and accelerated partial breast irradiation (APBI) with brachytherapy are performed routinely. Contouring and treatment planning are based on the recommendations of the GEC - ESTRO Working group. The task of this presentation is to reveal the advantages of 3D image guided brachytherapy over 2D brachytherapy. Thus, two patients treated at our department (one GYN and one APBI) will be presented. The advantage of having adequate dose coverage of the high risk CTV and simultaneous low doses to the OARs when using 3D image- based brachytherapy will be presented. The treatment techniques, equipment issues, as well as implantation, imaging and treatment planning procedures will be described. Quality assurance checks will be treated separately.

  14. Intravascular brachytherapy after percutaneous recanalization of occluded femoral artery: a case report

    The paper presents the use of introvascular brachytherapy after percutaneus recanalization and angioplasty of the femoral artery in a 65-year old patient with hypertension, a history of heavy smoking, and early stage diabetes. The patient was admitted to hospital with rest ischeamia of the right crus and trophic skin changes in that region. After primary pharmacological treatment angiography was performed revealing the femoro-popliteal artery to be occluded in the distal part of the adductor canal. The patency of the artery was established. Subsequently the occluded par of the artery was completely dilated without residual stenosis. Control angiography revealed good contrast flow through the dilated artery and correct configuration of the arteries below the open and dilated part of the femoro-popliteal artery. These arteries were, however, anatomically narrow. On clinical examination the pulse was present on peripheral arteries, while cyanosis of the right foot and the pain had disappeared. To prevent restenosis after angioplasty intravascular brachytherapy was performed with Microselectron192Ir. A PARIS catheter was used as the applicator. It was introduced into the artery using the same access as angiography and angioplasty. The target for irradiation was the dilated part of the artery with bilateral 1.5 cm margins - altogether 10 cm. One dose of 15 Gy was applied 2 mm from the inner surface of the arterial wall (2 mm from the applicator surface). There were no early side effects after the treatment. (author)

  15. Verification and source-position error analysis of film reconstruction techniques used in the brachytherapy planning systems

    A method was presented that employs standard linac QA tools to verify the accuracy of film reconstruction algorithms used in the brachytherapy planning system. Verification of reconstruction techniques is important as suggested in the ESTRO booklet 8: ''The institution should verify the full process of any reconstruction technique employed clinically.'' Error modeling was also performed to analyze seed-position errors. The ''isocentric beam checker'' device was used in this work. It has a two-dimensional array of steel balls embedded on its surface. The checker was placed on the simulator couch with its center ball coincident with the simulator isocenter, and one axis of its cross marks parallel to the axis of gantry rotation. The gantry of the simulator was rotated to make the checker behave like a three-dimensional array of balls. Three algorithms used in the ABACUS treatment planning system: orthogonal film, 2-films-with-variable-angle, and 3-films-with-variable-angle were tested. After exposing and digitizing the films, the position of each steel ball on the checker was reconstructed and compared to its true position, which can be accurately calculated. The results showed that the error is dependent on the object-isocenter distance, but not the magnification of the object. The averaged errors were less than 1 mm within the tolerance level defined by Roueet al. [''The EQUAL-ESTRO audit on geometric reconstruction techniques in brachytherapy,'' Radiother. Oncol. 78, 78-83 (2006)]. However, according to the error modeling, the theoretical error would be greater than 2 mm if the objects were located more than 20 cm away from the isocenter with a 0.5 deg. reading error of the gantry and collimator angles. Thus, in addition to carefully performing the QA of the gantry and collimator angle indicators, it is suggested that the patient, together with the applicators or seeds inside, should be placed close to the isocenter as much as possible. This method could be used

  16. Development of a phantom to validate high-dose-rate brachytherapy treatment planning systems with heterogeneous algorithms

    Moura, Eduardo S., E-mail: emoura@wisc.edu [Department of Medical Physics, University of Wisconsin–Madison, Madison, Wisconsin 53705 and Instituto de Pesquisas Energéticas e Nucleares—IPEN-CNEN/SP, São Paulo 05508-000 (Brazil); Micka, John A.; Hammer, Cliff G.; Culberson, Wesley S.; DeWerd, Larry A. [Department of Medical Physics, University of Wisconsin–Madison, Madison, Wisconsin 53705 (United States); Rostelato, Maria Elisa C. M.; Zeituni, Carlos A. [Instituto de Pesquisas Energéticas e Nucleares—IPEN-CNEN/SP, São Paulo 05508-000 (Brazil)

    2015-04-15

    Purpose: This work presents the development of a phantom to verify the treatment planning system (TPS) algorithms used for high-dose-rate (HDR) brachytherapy. It is designed to measure the relative dose in a heterogeneous media. The experimental details used, simulation methods, and comparisons with a commercial TPS are also provided. Methods: To simulate heterogeneous conditions, four materials were used: Virtual Water™ (VM), BR50/50™, cork, and aluminum. The materials were arranged in 11 heterogeneity configurations. Three dosimeters were used to measure the relative response from a HDR {sup 192}Ir source: TLD-100™, Gafchromic{sup ®} EBT3 film, and an Exradin™ A1SL ionization chamber. To compare the results from the experimental measurements, the various configurations were modeled in the PENELOPE/penEasy Monte Carlo code. Images of each setup geometry were acquired from a CT scanner and imported into BrachyVision™ TPS software, which includes a grid-based Boltzmann solver Acuros™. The results of the measurements performed in the heterogeneous setups were normalized to the dose values measured in the homogeneous Virtual Water™ setup and the respective differences due to the heterogeneities were considered. Additionally, dose values calculated based on the American Association of Physicists in Medicine-Task Group 43 formalism were compared to dose values calculated with the Acuros™ algorithm in the phantom. Calculated doses were compared at the same points, where measurements have been performed. Results: Differences in the relative response as high as 11.5% were found from the homogeneous setup when the heterogeneous materials were inserted into the experimental phantom. The aluminum and cork materials produced larger differences than the plastic materials, with the BR50/50™ material producing results similar to the Virtual Water™ results. Our experimental methods agree with the PENELOPE/penEasy simulations for most setups and dosimeters. The

  17. High dose rate brachytherapy using custom made superficial mould applicators and Leipzig applicators for non melanoma localized skin cancer

    Purpose: advances in technology and the commercial production of Leipzig applicators allowed High Dose Rate after-load brachytherapy (HDR-BT) to address a number of the challenges associated with the delivery of superficial radiation to treat localized non melanoma skin cancer (NMSK). We reviewed our uni-institutional experience on the treatment of NMSK with HDR-BT. Methods: data were collected retrospectively from patients attending the Radiation Oncology Department at AV Carvalho Insitute, Sao Paulo, Brazil. HDR-BT was done using the stepping source HDR 192Ir Microselectron (Nucletron BV). The planning target volume consisted of the macroscopic lesion plus a 5mm to 10mm margin.The depth of treatment was 0.5 cm in smaller (< 2.0 cm) tumors and 10 to 15 mm for lesions bigger than that. Results: Thirteen patients were treated with HDR-BT from June, 2007 to June 2013. The median age and follow up time were 72 (38-90) years old and 36 (range, 7-73) months, respectively. There a predominance of males (61.5%) and of patients referred for adjuvant treatment due positive surgical margins or because they have had only a excision biopsy without safety margins (61.5%). Six (46.2%) patients presented with squamous cell carcinoma and 7 (53.8%) patients presented with basal cell carcinoma. The median tumor size was 20 (range, 5-42) mm. Patients were treated with a median total dose of 40 Gy (range, 20 -60), given in 10 (range, 2-15) fractions, given daily or twice a week. All patients responded very well to treatment and only one patient has failed locally so far, after 38 months of the end of the irradiation. The crude and actuarial 3-year local control rates were 100% and 80%, respectively. Moist desquamation, grade 2 RTOG, was observed in 4 (30.8%) patients. Severe late complication, radiation-induced dyspigmentation, occurred in 2 patients and 1 of the patients also showed telangiectasia in the irradiated area. The cosmetic result was considered good in 84% (11/13) patients

  18. Development of a phantom to validate high-dose-rate brachytherapy treatment planning systems with heterogeneous algorithms

    Purpose: This work presents the development of a phantom to verify the treatment planning system (TPS) algorithms used for high-dose-rate (HDR) brachytherapy. It is designed to measure the relative dose in a heterogeneous media. The experimental details used, simulation methods, and comparisons with a commercial TPS are also provided. Methods: To simulate heterogeneous conditions, four materials were used: Virtual Water™ (VM), BR50/50™, cork, and aluminum. The materials were arranged in 11 heterogeneity configurations. Three dosimeters were used to measure the relative response from a HDR 192Ir source: TLD-100™, Gafchromic® EBT3 film, and an Exradin™ A1SL ionization chamber. To compare the results from the experimental measurements, the various configurations were modeled in the PENELOPE/penEasy Monte Carlo code. Images of each setup geometry were acquired from a CT scanner and imported into BrachyVision™ TPS software, which includes a grid-based Boltzmann solver Acuros™. The results of the measurements performed in the heterogeneous setups were normalized to the dose values measured in the homogeneous Virtual Water™ setup and the respective differences due to the heterogeneities were considered. Additionally, dose values calculated based on the American Association of Physicists in Medicine-Task Group 43 formalism were compared to dose values calculated with the Acuros™ algorithm in the phantom. Calculated doses were compared at the same points, where measurements have been performed. Results: Differences in the relative response as high as 11.5% were found from the homogeneous setup when the heterogeneous materials were inserted into the experimental phantom. The aluminum and cork materials produced larger differences than the plastic materials, with the BR50/50™ material producing results similar to the Virtual Water™ results. Our experimental methods agree with the PENELOPE/penEasy simulations for most setups and dosimeters. The TPS

  19. High dose rate brachytherapy using custom made superficial mould applicators and Leipzig applicators for non melanoma localized skin cancer

    Pellizzon, A. Cassio A.; Miziara, Daniela; Lima, Flavia Pedroso de; Miziara, Miguel

    2014-07-01

    Purpose: advances in technology and the commercial production of Leipzig applicators allowed High Dose Rate after-load brachytherapy (HDR-BT) to address a number of the challenges associated with the delivery of superficial radiation to treat localized non melanoma skin cancer (NMSK). We reviewed our uni-institutional experience on the treatment of NMSK with HDR-BT. Methods: data were collected retrospectively from patients attending the Radiation Oncology Department at AV Carvalho Insitute, Sao Paulo, Brazil. HDR-BT was done using the stepping source HDR 192Ir Microselectron (Nucletron BV). The planning target volume consisted of the macroscopic lesion plus a 5mm to 10mm margin.The depth of treatment was 0.5 cm in smaller (< 2.0 cm) tumors and 10 to 15 mm for lesions bigger than that. Results: Thirteen patients were treated with HDR-BT from June, 2007 to June 2013. The median age and follow up time were 72 (38-90) years old and 36 (range, 7-73) months, respectively. There a predominance of males (61.5%) and of patients referred for adjuvant treatment due positive surgical margins or because they have had only a excision biopsy without safety margins (61.5%). Six (46.2%) patients presented with squamous cell carcinoma and 7 (53.8%) patients presented with basal cell carcinoma. The median tumor size was 20 (range, 5-42) mm. Patients were treated with a median total dose of 40 Gy (range, 20 -60), given in 10 (range, 2-15) fractions, given daily or twice a week. All patients responded very well to treatment and only one patient has failed locally so far, after 38 months of the end of the irradiation. The crude and actuarial 3-year local control rates were 100% and 80%, respectively. Moist desquamation, grade 2 RTOG, was observed in 4 (30.8%) patients. Severe late complication, radiation-induced dyspigmentation, occurred in 2 patients and 1 of the patients also showed telangiectasia in the irradiated area. The cosmetic result was considered good in 84% (11/13) patients

  20. Determination of the dose around an ovoid for treatments in intracavitary brachytherapy Hdr

    On this work the results of the dosimetric measurements are presented around an ovoid of 2 cm diameter. The measurements were carried out using a water mannequin, an ovoid, a radiation gamma source of 192Ir and thermoluminescent dosemeters. The dosimetry was realized in the direction of the rectum and bladder. To know the effect of the shielding of the devices type Manchester in the dose, the thermoluminescent dosemeters were irradiated to a radiation gamma source of 192Ir contained in the Gamma med Plus equipment. The planning was realized normalizing the calculation to 2.5 cm from the applicator center on the transverse plane (2.5, 0, 0). The results show that the dose distribution for an ovoid without shielding is more uniform in the transversal plane to the source axis. The results were compared with the calculated results by means of the planning system BrachyVision. While the absorbed dose distribution around an ovoid with shielding is completely anisotropic. This anisotropic is due to the shielding. (Author)

  1. Physical aspects of radioisotope brachytherapy

    The present report represents an attempt to provide, within a necessarily limited compass, an authoritative guide to all important physical aspects of the use of sealed gamma sources in radiotherapy. Within the report, reference is made wherever necessary to the more extensive but scattered literature on this subject. While this report attempts to cover all the physical aspects of radioisotope 'brachytherapy' it does not, of course, deal exhaustively with any one part of the subject. 384 refs, 3 figs, 6 tabs

  2. Characteristics of miniature electronic brachytherapy x-ray sources based on TG-43U1 formalism using Monte Carlo simulation techniques

    Safigholi, Habib; Faghihi, Reza; Jashni, Somaye Karimi; Meigooni, Ali S. [Faculty of Engineering, Science and Research Branch, Islamic Azad University, Fars, 73481-13111, Persepolis (Iran, Islamic Republic of); Department of Nuclear Engineering and Radiation Research Center, Shiraz University, 71936-16548, Shiraz (Iran, Islamic Republic of); Shiraz University of Medical Sciences, 71348-14336, Shiraz (Iran, Islamic Republic of); Department of Radiation therapy, Comprehensive Cancer Center of Nevada, 3730 South Eastern Avenue, Las Vegas, Nevada 89169 (United States)

    2012-04-15

    Purpose: The goal of this study is to determine a method for Monte Carlo (MC) characterization of the miniature electronic brachytherapy x-ray sources (MEBXS) and to set dosimetric parameters according to TG-43U1 formalism. TG-43U1 parameters were used to get optimal designs of MEBXS. Parameters that affect the dose distribution such as anode shapes, target thickness, target angles, and electron beam source characteristics were evaluated. Optimized MEBXS designs were obtained and used to determine radial dose functions and 2D anisotropy functions in the electron energy range of 25-80 keV. Methods: Tungsten anode material was considered in two different geometries, hemispherical and conical-hemisphere. These configurations were analyzed by the 4C MC code with several different optimization techniques. The first optimization compared target thickness layers versus electron energy. These optimized thicknesses were compared with published results by Ihsan et al.[Nucl. Instrum. Methods Phys. Res. B 264, 371-377 (2007)]. The second optimization evaluated electron source characteristics by changing the cathode shapes and electron energies. Electron sources studied included; (1) point sources, (2) uniform cylinders, and (3) nonuniform cylindrical shell geometries. The third optimization was used to assess the apex angle of the conical-hemisphere target. The goal of these optimizations was to produce 2D-dose anisotropy functions closer to unity. An overall optimized MEBXS was developed from this analysis. The results obtained from this model were compared to known characteristics of HDR {sup 125}I, LDR {sup 103}Pd, and Xoft Axxent electronic brachytherapy source (XAEBS) [Med. Phys. 33, 4020-4032 (2006)]. Results: The optimized anode thicknesses as a function of electron energy is fitted by the linear equation Y ({mu}m) = 0.0459X (keV)-0.7342. The optimized electron source geometry is obtained for a disk-shaped parallel beam (uniform cylinder) with 0.9 mm radius. The TG-43

  3. Prostate cancer brachytherapy

    The transperineal brachytherapy with 125I/Pd103 seed implantation guided by transurethral ultrasound must be presented as therapeutical option of low urinary morbidity in patients with localized prostate cancer. The combined clinical staging - including Gleason and initial PSA - must be encouraged, for definition of a group of low risk and indication of exclusive brachytherapy. Random prospective studies are necessary in order to define the best role of brachytherapy, surgery and external beam radiation therapy

  4. Radiological aspects in the production and transport of a radioactive iridium source from the reactor to the industrial user

    Bhabha Atomic Research Centre (BARC) and the organization the Board of Radiation and Isotope Technology (BRIT) handles hundreds of kilo Curies in shielded and contained facilities under safe procedures to supply 192Ir sources to industry in India and abroad. The starting point of the 192Ir source begins from the inactive stage of 192Ir pellet packing, irradiation in research reactor, fabrication and supply and ends in the hands of the industrial user who ultimately returns it to DAE after its useful life for removal/re-use or burial in the National Waste Repository. This paper looks at the radiological aspects of the entire process and the efforts in ensuring radiological safety. Based on the analysis of dose distribution in various operations, efforts are being made for further reduction of exposure associated with production and transport. A detailed dose analysis, shielding evaluation for 192Ir during its handling in hot cell and transportation and its validation is detailed in the full text of the paper

  5. Prototypes of phosphorus-32 sealed sources for use in Brachytherapy; Prototipo de fuente radiactiva de fosforo para uso medico en braquiterapia

    Anaya Garro, Olgger; Vela Mora, Mariano; Revilla Silva, Angel Revilla [Instituto Peruano de Energia Nuclear (IPEN), Lima (Peru)]. E-mail: oanaya@ipen.gob.pe; mvela@ipen.gob.pe; arevilla@ipen.gob.pe

    2005-07-01

    It has developed prototypes of phosphorus-32 sealed sources for use in Brachytherapy. This one was made in two stages, at the first one, we designed and constructed the container (capsule), the filling system and the sealed system; at the second one, we made the irradiation of the capsules containing the 'target'. The prototypes was made of aluminum in cylindrical geometry. During the irradiation test was made using two different dimensions: one of 1 mm outer diameter and 1 cm length and another one of 0.8 mm outer diameter and 5 mm length. They were radiated in the core of the RP-10 research reactor, at 7.93 x10{sup 13} n/cm{sup 2}.s thermal neutron flux during 27 operation cycles. Activities of 144.53 MBq (3.91 mCi) and 107.67 MBq (2.91 mCi) was obtained for each case. This activities are adequate to restenosis and for some tumors treatment. We can observed that the capsules irradiated passed visual inspection in its physical integrity (leakage and geometry). It has been demonstrated, that the beta radiation for his minor power of penetration and its high interaction, causes major local damage to the malignant tissue, minimizing the damage of the healthy surrounding tissues. It has been advisable to use for the treatment of illnesses of the circulatory system and some tumors. At the present, the source of strontium-90 are the most beta ray source used, but of this one are obtained as fission product of uranium target, where valuable radioactive waste is generated, whereas if we were using phosphorus-32 that we propose, radioactive waste would not be generated since it would take place directly as sealed source, for reaction (n, {beta}). (author)

  6. SU-F-19A-05: Experimental and Monte Carlo Characterization of the 1 Cm CivaString 103Pd Brachytherapy Source

    Purpose: To determine the in-air azimuthal anisotropy and in-water dose distribution for the 1 cm length of the CivaString 103Pd brachytherapy source through measurements and Monte Carlo (MC) simulations. American Association of Physicists in Medicine Task Group No. 43 (TG-43) dosimetry parameters were also determined for this source. Methods: The in-air azimuthal anisotropy of the source was measured with a NaI scintillation detector and simulated with the MCNP5 radiation transport code. Measured and simulated results were normalized to their respective mean values and compared. The TG-43 dose-rate constant, line-source radial dose function, and 2D anisotropy function for this source were determined from LiF:Mg,Ti thermoluminescent dosimeter (TLD) measurements and MC simulations. The impact of 103Pd well-loading variability on the in-water dose distribution was investigated using MC simulations by comparing the dose distribution for a source model with four wells of equal strength to that for a source model with strengths increased by 1% for two of the four wells. Results: NaI scintillation detector measurements and MC simulations of the in-air azimuthal anisotropy showed that ≥95% of the normalized data were within 1.2% of the mean value. TLD measurements and MC simulations of the TG-43 dose-rate constant, line-source radial dose function, and 2D anisotropy function agreed to within the experimental TLD uncertainties (k=2). MC simulations showed that a 1% variability in 103Pd well-loading resulted in changes of <0.1%, <0.1%, and <0.3% in the TG-43 dose-rate constant, radial dose distribution, and polar dose distribution, respectively. Conclusion: The CivaString source has a high degree of azimuthal symmetry as indicated by the NaI scintillation detector measurements and MC simulations of the in-air azimuthal anisotropy. TG-43 dosimetry parameters for this source were determined from TLD measurements and MC simulations. 103Pd well-loading variability results in

  7. Effectiveness of brachytherapy in treating carcinoma of the vulva

    Purpose: Radical radiotherapeutic management of vulvar cancer often incorporates brachytherapy as a portion of the treatment regimen. However, few studies using this modality alone to manage vulvar cancer have been published. Methods and Materials: Thirty four patients were treated with iridium-192 (192Ir) brachytherapy for vulvar cancer between 1975 and 1993 at Centre Alexis Vautrin. Twenty-one patients were treated at first presentation when surgery was contraindicated or declined. Of these patients, 12 had International Federation of Gynecology and Obstetrics Classification Stage III or IV disease, 8 were Stage II, 1 was Stage I, and 1 was Stage 0. Thirteen patients were treated for recurrent disease. Paris system rules for implantation and dose prescription were followed. The median reference dose was 60 Gy (range 53 to 88 Gy). At the time of analysis, 10 of 34 patients were alive. Median follow-up in these 10 patients was 31 months (range: 21 months to 107 months). Fourteen of the 24 deaths were from causes other than vulvar cancer. Results: Kaplan-Meier actuarial 5-year local control was 47% (95% confidence interval (CI) = 23 to 73%) and 5-year actuarial loco-regional control was 45% (95% CI = 21 to 70%). Kaplan-Meier actuarial 5-year disease-specific survival was 56% (95% CI = 33 to 76%) and actuarial 5-year survival was 29% (95% CI = 15 to 49%). Median time to death was 14 months. Subset analysis revealed a higher actuarial 5-year local control in patients treated at first presentation than those treated for recurrence (80 vs. 19%, log rank, p = 0.04). Similarly, actuarial 5-year loco-regional control was higher in patients treated at first presentation (80 vs. 16%, log rank, p 0.01). The two groups did not differ significantly in disease-specific or overall survival. The actuarial 5-year disease specific survival of 56% is somewhat less than the expected 5-year disease-specific survival after surgery in a group having a similar proportion of early stage

  8. Sole conformal perioperative interstitial brachytherapy of early stage breast carcinoma using high-dose rate afterloading: longer-term results and toxicity

    Aims and Background: This study of high-dose-rate brachytherapy to the lumpectomy site as the sole radiation presents longer-term results and toxicity of accelerated partial-breast irradiation, using three-dimensional treatment planning. Materials and Methods: From March 2002 to July 2004, 25 patients were prospectively included in this study. Six patients were excluded because of definitive histology of lobular carcinoma or positive margin. The median age at the time of treatment was 63.2 years (range 44 - 77 years). Median follow- up of all patients was 44 months (range 30 - 53 months) with a minimum follow-up of 30 months. Radiation was delivered using the high-dose-rate remote after loader VariSource with 192Ir source. The patients received radiation twice a day at least 6 hours apart for a total of 10 fractions over five days with a single dose of 3.4 Gy. The total dose was 34.0 Gy prescribed as a minimum peripheral dose to match or minimally exceed the volume defined by the surgical clips as seen on computed-tomography (CT) scans. Free-hand technique allows conformal placement of the catheters to the shape of the lumpectomy cavity. Side-effects and toxicity were scored using the EORTC/RTOG scale. Results: At a median follow-up of 44 months none of the women had developed in-field breast recurrences, one patient had out-of-field recurrences and one patient presented distant metastases. There were no regional nodal recurrences. In each woman, target volume size in cm3 (median 91.3 cm3), dose volume histogram (DVH), and dose homogeneity index (DHI) were calculated. Median DHI was 0.42. Median volume of breast tissue receiving 100 % of the prescription dose, V100, was 87 %; and V150 48.5 %. We noticed two treatment complications: haematoma and abscess in the place of the tumour bed after extirpation. At last follow-up, all patients rated the overall cosmetic outcome as excellent or good. Conclusions: This method is suitable only for patients with histologically

  9. Post-stenting Intravascular Brachytherapy Trials on Hypercholesterolemic Rabbits Using 32P Liquid Sources: Implications for Prevention of In-Stent Restenosis

    Purpose: Liquid sources of radiation delivered in angioplasty balloons may be a convenient self-centering device used for prevention of in-stent restenosis. To test the effectiveness of this method an intravascular brachytherapy study was performed using 32P liquid sources in an animal model. Methods: The radial dose distribution around angioplasty balloons filled with solutions of Na2H32PO4 was calibrated by thermoluminescence dosimetry. The animal experiments were performed in rabbits with induced hypercholesterolemia. The balloons containing 32P were introduced into iliac arteries immediately after stent implantation. Estimated 7-49 Gy doses required 30-100 minirradiations. Radiation effects were evaluated by comparing the thickness of various components of the artery wall. Results:Doses of 7, 12, 16 or 49 Gy on the internal artery surface required 30-100 min of irradiation. The dose of 49 Gy at 'zero' distance corresponding to 16 Gy at 1.0 mm from the balloon surface reduced hypertrophy in every layer of the arterial wall: in the intima the cross-sectional areas were 0.13 versus 0.91 mm2, in the media were 0.5 versus 0.46 mm2 and in the adventitia were 0.04 versus 0.3 mm2 (p <0.05). A dose of 7 Gyat the balloon surface produced adverse irradiation effects: the intimal area of the artery was 2.087 versus 0.857 mm2, the medial area was 0.59 versus 0.282 mm2 and the adventitial area was 0.033 versus 0.209 mm2 in treated and control arteries, respectively.Conclusion: Application of a 49 Gy irradiation dose to the internal arterial surface effectively prevented in-stentrestenosis

  10. Interstitial brachytherapy for eyelid carcinoma. Outcome analysis in 60 patients

    Krengli, M.; Deantonio, L. [University Hospital ' ' Maggiore della Carita' ' , Division of Radiotherapy, Novara (Italy); University of ' ' Piemonte Orientale' ' , Department of Translational Medicine, Novara (Italy); Masini, L.; Filomeno, A.; Gambaro, G. [University Hospital ' ' Maggiore della Carita' ' , Division of Radiotherapy, Novara (Italy); Comoli, A.M. [University Hospital Maggiore della Carita, Ophthalmology, Novara (Italy); Negri, E. [University Hospital Maggiore della Carita, Medical Physics, Novara (Italy)

    2014-03-15

    Eyelid cancer is a therapeutic challenge due to the cosmetic and functional implications of this anatomical region and the objectives of therapy are tumor control, functional and cosmetic outcome. The present study was performed to analyze local control, toxicity, functional and cosmetic results in patients with eyelid carcinoma treated by interstitial brachytherapy. In this study 60 patients with eyelid carcinoma were treated by interstitial brachytherapy using iridium ({sup 192}Ir) wires with a linear activity of 1.2-1.7 mCi/cm. The prescription dose was 51-70 Gy (mean 65 Gy, median 66 Gy). Of the 60 patients 51 (85.0 %) had received no prior treatment, 4 (6.7 %) had received previous surgery with positive or close margins and 5 (8.3 %) had suffered local recurrence after surgery. Of the tumors 52 (86.7 %) were basal cell carcinoma, 7 (11.7 %) squamous cell carcinoma and 1 (1.7 %) Merkel cell carcinoma. Clinical stage of the 51 previously untreated tumors was 38 T1N0, 12 T2N0 and 1 T3N0. Mean follow-up was 92 months (range 6-253 months). Local control was maintained in 96.7 % of patients. Late effects higher than grade 2 were observed in 3.0 % of cases. Functional and cosmetic outcomes were optimal in 68.4 % of patients. Interstitial brachytherapy for carcinoma of the eyelid can achieve local control, cosmetic and functional results comparable to those of surgery. (orig.) [German] Das Karzinom des Augenlids stellt aufgrund der funktionellen und kosmetischen Beeintraechtigungen dieser anatomischen Region eine therapeutische Herausforderung dar. Ziele der Therapie sind sowohl die Tumorkontrolle als auch ein gutes funktionelles und kosmetisches Ergebnis. Lokale Kontrolle, Toxizitaet sowie funktionelle und kosmetische Ergebnisse bei Patienten mit Karzinom des Augenlids, die mit interstitieller Brachytherapie behandelt wurden, sollten analysiert werden. Sechzig Patienten mit Karzinom des Augenlids wurden mit interstitieller Brachytherapie mit Iridium-192-Draehten

  11. Brachytherapy for T1-T2 floor-of-the-mouth cancers: the Gustave-Roussy Institute experience

    Purpose: In a retrospective analysis, we evaluated the Gustave-Roussy Institute's experience of locoregional control, survival, and complications of low-dose rate brachytherapy for carcinoma of the floor of the mouth. Methods and Materials: Between 1970 and 1985, 160 patients with previously untreated carcinoma of the floor of the mouth received interstitial brachytherapy as definitive treatment. Of the 160 patients, 79 (49%) had T1 and 81 (51%) had T2 lesions, and 127 (79%) had N0 and 33 (21%) had N1; 84% of tumors arose from the anterior floor of the mouth. Brachytherapy was performed with 192Ir wires, according to the Paris system rules, followed by neck dissection (T2 or N1) or follow-up (T1N0). Results: With a follow-up period of 9-19 years, the observed survival rates were 89% at 2 years and 76% at 5 years, and the local control rates were 93% in T1 and 88% in T2 tumors. A low rate of distant metastases was noticed (5%); 31% of patients developed a second primary cancer. Severe mucosal necrosis was observed in <10% of patients. Any grade of bone necrosis was seen in 18% of cases (only 2.5% had G3 necrosis). This complication occurred more frequently in patients with poor dental status and in those treated without dental protection during implantation (p <0.001). Conclusion: Radical brachytherapy offers excellent local control (89%) and an acceptable rate of complications (<10% severe necrosis) that may be significantly decreased with dental care and the use of protective devices. The high incidence of second malignancies remains a major concern in these patients

  12. Evolution of dose distribution calculations in brachytherapy

    In this report the evolution of dose distribution calculations is revised in detail, considering the simplest case (a point source in free space) and the more complex situation of a real encapsulated line source embedded in a scattering medium. The most recent formalism to perform the dosimetry of interstitial brachytherapy sources is presented, where measured or measurable dose rates from actual sources in a tissue equivalent phantom are required as input data

  13. Gel dosimetry for HDR Brachytherapy 3-D distribution through MRI

    Gel dosimetry using MRI is increasingly being utilized in contemporary literature. In our work we investigated the calibration of an acrylic gel by means of imaging with magnetic resonance and its application to the dose measurement in a 3D distribution 192Ir HDR brachytherapy treatment. Early gel dosimetry used Fricke gels and T1 relaxation time. In 2001 Fong et al. introduced a new normoxic gel known as ''MAGIC'' gel, the main components of which are Metacrylic Acid (polymer) and Hydroquinone ( polymerizing inhibitor). For this material, the evidence of radiation dose is indicated by a change in the T2 relaxation time on an MR image. Later studies varied concentrations of the MAGIC gel components in order to observe its effect and the behavior of the gel sensitivity, for magnetic fields over 0.5 T. In the 1980s a series of studies on dose quantification using magnetic resonance images and Fricke gels were performed by evaluating T1 signal through means of an Inversion Recovery technique. Polymer gels have been developed to avoid the adverse effects of oxygen that plague Fricke gels. Normoxic gels have a component which helps to capture the oxygen dissolved in the gel (MAGIC). For these type of gels, measurements of T2 are made using a Spin-Echo technique. For both groups of gels, the Relaxativity compared to either T1 or T2 varies linearly with the absorbed dose. Novotny et al. has obtained a dose response curve for BANG-2 gel showing a linear relationship of 1/T2 vs D[Gy]. In the work presented here we tested and found the same linear relation between spin-spin relaxation (R2=1/T2) versus dose up to 8.0Gy

  14. Divergence of Cs-137 sources fluence used in brachytherapy; Divergencia da fluencia de fontes de Cs-137 usadas em braquiterapia

    Vianello, E.A.; Almeida, C.E. de [Laboratorio de Ciencias Radiologicas- LCR-DBB (UERJ). R. Sao Francisco Xavier, 524- Pav. HLC, sala 136 terreo- CEP 20.550- 013. Rio de Janeiro (Brazil)

    1998-12-31

    In this work the experimental determination of correction factor for fluence divergence (kln) of linear Cs-137 sources CDCS J4, with Farmer ionization chamber model 2571 in a central and perpendicular plan to source axis, for distances range from 1 to 7 cm., has been presented. The experimental results were compared to calculating by Kondo and Randolph (1960) isotropic theory and Bielajew (1990) anisotropic theory. (Author)

  15. Initial clinical experience with the MammoSite breast brachytherapy applicator in women with early-stage breast cancer treated with breast-conserving therapy

    Purpose: We present the results of the initial clinical testing of the MammoSite balloon breast brachytherapy applicator in women with early-stage breast cancer treated with breast-conserving therapy. Methods and Materials: Seventy patients were enrolled in a multicenter prospective trial testing the applicator for safety and performance. Fifty-four patients were implanted, and 43 patients were ultimately eligible for and received brachytherapy as the sole radiation modality after lumpectomy. Patients were staged T1N0M0 with negative pathologic margins and age >45 years. A dose of 34 Gy was delivered in 10 fractions over 5 days prescribed to 1 cm from the applicator surface using 192Ir high-dose-rate brachytherapy. A minimum skin-to-balloon surface distance of 5 mm was required for treatment. Device performance, complications, and cosmesis were assessed. Results: Computed tomography imaging post-balloon inflation showed 8, 14, and 21 patients with 5-6 mm, 7-9 mm, and >10 mm of skin spacing, respectively. Two patients were explanted because of inadequate skin spacing and 7 because of suboptimal conformance of the surgical cavity to the applicator balloon. One patient was explanted because of positive nodal status and another because of age. The most common side effects related to device placement included mild erythema, drainage, pain, and echymosis. No severe side effects related to implantation, brachytherapy, or explantation occurred. Side effects related to radiation therapy were generally mild with erythema, pain, and dry desquamation being the most common. At 1 month, 88% of patients were evaluated as having good-to-excellent cosmetic results. Conclusions: The MammoSite balloon breast brachytherapy applicator performed well clinically. All eligible patients completed treatment. Side effects were mild to moderate and self-limiting. Skin-balloon surface distance and balloon-cavity conformance were the main factors limiting the initial use of the device

  16. Dose optimisation in single plane interstitial brachytherapy

    Tanderup, Kari; Hellebust, Taran Paulsen; Honoré, Henriette H;

    2006-01-01

    BACKGROUND AND PURPOSE: Brachytherapy dose distributions can be optimised       by modulation of source dwell times. In this study dose optimisation in       single planar interstitial implants was evaluated in order to quantify the       potential benefit in patients. MATERIAL AND METHODS: In 14...

  17. Dose calculation in brachytherapy with microcomputers

    The computer algorithms, that allow the calculation of brachytherapy doses and its graphic representation for implants, using programs developed for Pc microcomputers are presented. These algorithms allow to localized the sources in space, from their projection in radiographics images and trace isodose counter. (C.G.C.)

  18. Dosimetry characterization of $^{32}$P intravascular brachytherapy source wires using Monte Carlo codes PENELOPE and GEANT4

    Torres, J; Almansa, J F; Guerrero, R; Lallena, A M; Torres, Javier; Buades, Manuel J.; Almansa, Julio F.; Guerrero, Rafael; Lallena, Antonio M.

    2003-01-01

    Monte Carlo calculations using the codes PENELOPE and GEANT4 have been performed to characterize the dosimetric parameters of the new 20 mm long catheter based $^{32}$P beta source manufactured by Guidant Corporation. The dose distribution along the transverse axis and the two dimensional dose rate table have been calculated. Also, the dose rate at the reference point, the radial dose function and the anisotropy function were evaluated according to the adapted TG-60 formalism for cylindrical sources. PENELOPE and GEANT4 codes were first verified against previous results corresponding to the old 27 mm Guidant $^{32}$P beta source. The dose rate at the reference point for the unsheathed 27 mm source in water was calculated to be $0.215 \\pm 0.001$ cGy s$^{-1}$ mCi$^{-1}$, for PENELOPE, and $0.2312 \\pm 0.0008$ cGy s$^{-1}$ mCi$^{-1}$, for GEANT4. For the unsheathed 20 mm source these values were $0.2908 \\pm 0.0009$ cGy s$^{-1}$ mCi$^{-1}$ and $0.311 \\pm 0.001$ cGy s$^{-1}$ mCi$^{-1}$, respectively. Also, a compar...

  19. An assessment of the radiological impact of brachytherapy application in Metro Manila hospitals

    One of the most important uses of radioactive sources in medicine is the application of brachytherapy technology. Brachytherapy is a method of radiation therapy where an encapsulated radioactive source delivers gamma or beta radiation into a tumor site. The paper describes different categories of brachytherapy applications involving manual insertion or afterloading and remote afterloading techniques. A list of five hospitals in Metro Manila practicing different techniques of brachytherapy are enumerated. Because of the widespread uses of radioactive sources in brachytherapy technology in medicine, inadequate control in its use had led to a number of incidents resulting to unnecessary exposure of radiation workers, patients and general public. This study was initiated to determine the radilogical hazards involved in brachytherapy applications. It presents contingency scenarios and their projected radiological consequences. (author). 7 refs., 2 tabs

  20. Study of photon angular distribution from a new Best 2300 series 125I source for interstitial brachytherapy

    125I seeds employed for permanent and temporary interstitial implants exhibit significant radiation fluence anisotropy due to self absorption in the marker and oblique filtration through the encapsulation jacket. A silver wire 125I seed (Model 6711), introduced in 1983 by 3M Company, failed to improve the photon distribution anisotropy. In addition to the known 125I photon spectrum, the new seed emitted two silver characteristic x-rays, lowering the mean photon energy from 28.4 to 27.4 keV. A double wall uniform thickness encapsulated 125I source, laser welded at one end, has been developed for clinical use. The source uses a carbon coated thin tungsten filament for enhanced radiographic visualization. Measurements made by NaI and intrinsic Ge detectors indicate that the 2300 series 125I source emits a pure 125I spectrum. The angular dependence of individual photon peaks and total photon spectrum as well as the corresponding anisotropy factors were measured. The 4π averaged anisotropy factor for the total radiation fluence is 0.92 compared to 0.87 for model 6711 seed. The dose distribution around the new 125I source in water is very isotropic. (author). 11 refs., 8 figs., 2 tabs

  1. Dosimetry in intravascular brachytherapy

    Among the cardiovascular diseases responsible for deaths in the adult population in almost all countries of the world, the most common is acute myocardial infarction, which generally occurs because of the occlusion of one or more coronary arteries. Several diagnostic techniques and therapies are being tested for the treatment of coronary artery disease. Balloon angioplasty has been a popular treatment which is less invasive than traditional surgeries involving revascularization of the myocardium, thus promising a better quality of life for patients. Unfortunately, the rate of restenosis (re-closing of the vessel) after balloon angioplasty is high (approximately 30-50% within the first year after treatment).Recently, the idea of delivering high radiation doses to coronary arteries to avoid or delay restenosis has been suggested. Known as intravascular brachytherapy, the technique has been used with several radiation sources, and researchers have obtained success in decreasing the rate of restenosis in some patient populations. In order to study the radiation dosimetry in the patient and radiological protection for the attending staff for this therapy, radiation dose distributions for monoenergetic electrons and photons (at nine discrete energies) were calculated for blood vessels of diameter 0.15, o,30 and 0.45 cm with balloon and wire sources using the radiation transport code MCNP4B. Specific calculations were carried out for several candidate radionuclides as well. Two s tent sources (metallic prosthesis that put inside of patient's artery through angioplasty) employing 32 P are also simulated. Advantages and disadvantages of the various radionuclides and source geometries are discussed. The dosimetry developed here will aid in the realization of the benefits obtained in patients for this promising new technology. (author)

  2. Radiation injury from acute exposure to an iridium-192 source: case history

    A 192Ir source became detached and fell from an industrial radiography camera. A labourer, not involved with radiation work and unaware of the hazard picked up the source and kept it in his hip packet for 2 hr. During this period, he received a skin dose of 13,000 rad and testes dose of 130 rad, the latter resulting in temporary sterility for a period of about 2 yr. (author)

  3. CT-guided interstitial HDR brachytherapy for recurrent glioblastoma multiforme. Long-term results

    Tselis, N.; Roeddiger, S.; Filipowicz, I.; Kontova, M.; Heyd, R.; Zamboglou, N. [Offenbach Hospital (Germany). Dept. of Radiotherapy and Interdisciplinary Oncology; Kolotas, C. [Offenbach Hospital (Germany). Dept. of Radiotherapy and Interdisciplinary Oncology; Hirslanden Medical Center, Aarau (Switzerland). Inst. of Radiotherapy; Birn, G. [Offenbach Hospital (Germany). Dept. of Neurosurgery; Fountzilas, G.; Selviaridis, P. [Aristotle Univ. of Thessaloniki School of Medicine, Thessaloniki (Greece); Baltas, D.; Anagnostopoulos, G. [Offenbach Hospital (Germany). Dept. of Medical Physics and Engineering

    2007-10-15

    Background and Purpose: Recurrences of glioblastoma multiforme (GBM) within previously irradiated volumes pose a serious therapeutic challenge. This retrospective study evaluates the long-term tumor control of recurrent GBM treated with interstitial high-dose-rate brachytherapy (HDR-BRT). Patients and Methods: Between 1995 and 2003, 84 patients were treated for recurrent cerebral GBM located within previously irradiated volumes. All patients had received adjuvant external radiotherapy following primary surgery, with a focal dose up to 60 Gy. The median recurrent tumor volume was 51 cm{sup 3} (3-207 cm{sup 3}), and the HDR-BRT consisted of an afterloading {sup 192}Ir implant which delivered a median dose of 40 Gy (30-50 Gy). Catheter implantation was implemented using interactive computed tomography (CT) guidance under local anesthesia and sedoanalgesia. Results: After a median follow-up of 61 months, 5/84 patients (6%) were alive. The median post-BRT survival was 37 weeks, and the median overall survival 78 weeks. Moderate to severe complications occurred in 5/84 cases (6%). Conclusion: For patients with recurrences of GBM within previously irradiated volumes, CT-guided interstitial HDR-BRT is a feasible treatment option that can play an important role in providing palliation. (orig.)

  4. Pleurectomy and intraoperative brachytherapy and postroperative radiation in the treatment of malignant pleural mesothelioma

    Forty-one patients with diffuse, pleural mesothelioma limited to one hemi-thorax underwent a thoracotomy at Memorial Sloan-Kettering Cancer Center from January 1976 to July 1982. Treatment at thoracotomy consisted of as complete a parietal pleurectomy as was possible to remove the bulk of the tumor. Measurable gross residual disease was treated whenever feasible, with permanent 125I implantation; residual diffuse disease was treated by a temporary 192Ir implantation or by postoperative instillation of 32P. External radiation therapy was given 4-6 weeks postoperatively to the involved hemi-thorax, shielding the lung and utilizing a combination of electron an a photon beam. A dose of 4500 rad in 4.5 weeks was given to the pleural surface by the mixed beam. There was no postoperative mortality in this group of 41 patients. Complications developed in 6 patients (15%). The median survival was 21 months; the one year survival was 65% and the two year survival was 40%. The median disease-free survival was 11 months and the one and two year disease-free survival 44 and 13% respectively. This study suggests that the combination of pleurectomy, intraoperative brachytherapy and postoperative external radiation increased the local control of the tumor and prolonged the survival

  5. The dosimetry of brachytherapy-induced erectile dysfunction

    There is emerging evidence that brachytherapy-induced erectile dysfunction (ED) is technique-related and may be minimized by careful attention to source placement. Herein, we review the relationship between radiation doses to the prostate gland/surrounding structures and the development of brachytherapy-induced ED. The permanent prostate brachytherapy literature was reviewed using MEDLINE searches to ensure completeness. Although the site-specific structure associated with brachytherapy-induced ED remains unknown, there is an increasing body of data implicating the proximal penis. With day 0 CT-based dosimetry, the dose to 50% (D50) and 25% (D25) of the bulb of the penis should be maintained below 40% and 60% mPD, respectively, while the crura D50 should be maintained below 28% mPD to maximize post-brachytherapy potency. To date, there is no data to suggest that either radiation doses to the neurovascular bundles or choice of isotope is associated with brachytherapy-induced ED, while conflicting data has been reported regarding radiation dose to the prostate and the use of supplemental external beam radiation therapy. Although the etiology of brachytherapy-induced ED is likely multifactorial, the available data supports the proximal penis as an important site-specific structure. Refinements in implant technique, including preplanning and intraoperative seed placement, will result in lower radiation doses to the proximal penis with potential improvement in potency preservation

  6. SU-E-T-548: Modeling of Breast IORT Using the Xoft 50 KV Brachytherapy Source and 316L Steel Rigid Shield

    Purpose: Xoft provides a set of 316L Stainless Steel Rigid Shields to be used with their 50 kV X-ray source for Breast IORT treatments. Modeling the different shield sizes in MCNP provides information to help make clinical decisions for selecting the appropriate shield size. Methods: The Xoft Axxent 50 kV Electronic Brachytherapy System has several applications in radiation therapy, one of which is treating cancer of the breast intraoperatively by placing the miniaturized X-ray tube inside an applicator balloon that is expanded to fill the lumpectomy bed immediately following tumor removal. The ribs, lung, and muscular chest wall are all regions at risk to receive undesired dose during the treatment. A Xoft 316L Stainless Steel Rigid Shield can be placed between the intracostal muscles of the chest wall and the remaining breast tissue near the balloon to attenuate the beam and protect these organs. These shields are provided in 5 different sizes, and the effects on dose to the surrounding tissues vary with shield size. MCNP was used to model this environment and tally dose rate to certain regions of interest. Results: The average rib dose rate calculated using 0cm (i.e., no shield), 3cm, and 5cm diameter shields were 26.89, 15.43, and 8.91 Gy/hr respectively. The maximum dose rates within the rib reached 94.74 Gy/hr, 53.56 Gy/hr, and 31.44 Gy/hr for the 0cm, 3cm, and 5cm cases respectively. The shadowing effect caused by the steel shields was seen in the 3-D meshes and line profiles. Conclusion: This model predicts a higher dose rate to the underlying rib region with the 3cm shield compared to the 5cm shield; it may be useful to select the largest possible diameter when choosing a shield size for a particular IORT patient. The ability to attenuate the beam to reduce rib dose was also confirmed. Research sponsored by Xoft Inc, a subsidiary of iCAD

  7. SU-E-T-548: Modeling of Breast IORT Using the Xoft 50 KV Brachytherapy Source and 316L Steel Rigid Shield

    Burnside, W [Mountain View, CA (United States)

    2015-06-15

    Purpose: Xoft provides a set of 316L Stainless Steel Rigid Shields to be used with their 50 kV X-ray source for Breast IORT treatments. Modeling the different shield sizes in MCNP provides information to help make clinical decisions for selecting the appropriate shield size. Methods: The Xoft Axxent 50 kV Electronic Brachytherapy System has several applications in radiation therapy, one of which is treating cancer of the breast intraoperatively by placing the miniaturized X-ray tube inside an applicator balloon that is expanded to fill the lumpectomy bed immediately following tumor removal. The ribs, lung, and muscular chest wall are all regions at risk to receive undesired dose during the treatment. A Xoft 316L Stainless Steel Rigid Shield can be placed between the intracostal muscles of the chest wall and the remaining breast tissue near the balloon to attenuate the beam and protect these organs. These shields are provided in 5 different sizes, and the effects on dose to the surrounding tissues vary with shield size. MCNP was used to model this environment and tally dose rate to certain regions of interest. Results: The average rib dose rate calculated using 0cm (i.e., no shield), 3cm, and 5cm diameter shields were 26.89, 15.43, and 8.91 Gy/hr respectively. The maximum dose rates within the rib reached 94.74 Gy/hr, 53.56 Gy/hr, and 31.44 Gy/hr for the 0cm, 3cm, and 5cm cases respectively. The shadowing effect caused by the steel shields was seen in the 3-D meshes and line profiles. Conclusion: This model predicts a higher dose rate to the underlying rib region with the 3cm shield compared to the 5cm shield; it may be useful to select the largest possible diameter when choosing a shield size for a particular IORT patient. The ability to attenuate the beam to reduce rib dose was also confirmed. Research sponsored by Xoft Inc, a subsidiary of iCAD.

  8. Integer Programs for High Dose Rate Brachytherapy Needle and Dose Planning that Directly Optimize Clinical Objectives

    Siauw, Ko-Ay Timmy

    2012-01-01

    High dose rate (HDR) brachytherapy is a radiation therapy for cancer in the prostate, cervix, breast, head, and neck, including other sites. In HDR brachytherapy, hollow needles are inserted or placed near the cancer site. Radiation is delivered to the patient by a radioactive source which is sequentially threaded through the needles. The dose distribution is controlled by altering the dwell times, the time spent at pre-defined positions on the needles.HDR brachytherapy has a 90\\% cancer-free...

  9. Biological effect of pulsed dose rate brachytherapy with stepping sources if short half-times of repair are present in tissues

    Purpose: To explore the possible increase of radiation effect in tissues irradiated by pulsed brachytherapy (PDR) for local tissue dose rates between those 'averaged over the whole pulse' and the instantaneous high dose rates close to the dwell positions. Increased effect is more likely for tissues with short half-times of repair of the order of a few minutes, similar to pulse durations. Methods and Materials: Calculations were done assuming the linear quadratic formula for radiation damage, in which only the dose-squared term is subject to exponential repair. The situation with two components of T(1(2)) is addressed. A constant overall time of 140 h and a constant total dose of 70 Gy were assumed throughout, the continuous low dose rate of 0.5 Gy/h (CLDR) providing the unitary standard effects for each PDR condition. Effects of dose rates ranging from 4 Gy/h to 120 Gy/h (HDR at 2 Gy/min) were studied, covering the gap in an earlier publication. Four schedules were examined: doses per pulse of 0.5, 1, 1.5, and 2 Gy given at repetition frequencies of 1, 2, 3, and 4 h, respectively, each with a range of assumed half-times of repair of 4 min to 1.5 h. Results are presented for late-responding tissues, the differences from CLDR being two or three times greater than for early-responding tissues and most tumors. Results: Curves are presented relating the ratio of increased biological effect (proportional to log cell kill) calculated for PDR relative to CLDR. Ratios as high as 1.5 can be found for large doses per pulse (2 Gy) if the half-time of repair in tissues is as short as a few minutes. The major influences on effect are dose per pulse, half-time of repair in tissue, and--when T(1(2)) is short--the instantaneous dose rate. Maximum ratios of PDR/CLDR occur when the dose rate is such that pulse duration is approximately equal to T(1(2)). As dose rate in the pulse is increased, a plateau of effect is reached, for most T(1(2))s, above 10 to 20 Gy/h, which is therefore

  10. Dosimetry in high dose rate endoluminal brachytherapy

    In endoluminal brachytherapy for the tracheobronchial tree, esophagus, and bile duct, a reference point for dose calculation has been often settled at 1 cm outside from the middle of source travel path. In the current study, a change in the ratio of the reference point dose on the convex to concave side (Dq/Dp) was calculated, provided the source travel path bends as is the case in most endoluminal brachytherapies. Point source was presumed to move stepwise at 1 cm interval from 4 to 13 locations. Retention time at each location was calculated by personal computer so as to deliver equal dose at 1 cm from the linear travel path. With the retention time remaining constant, the change of Dq/Dp was assessed by bending the source travel path. Results indicated that the length of the source travel path and radius of its curve influenced the pattern of change in Dq/Dp. Therefore, it was concluded that the difference in reference dose on the convex and concave side of the curved path is not negligible under certain conditions in endoluminal brachytherapy. In order to maintain the ratio more than 0.9, relatively greater radius was required when the source travel path was decreased. (author)

  11. Comparison between methods for fixing radioactive iodine in silver substrate for manufacturing brachytherapy sources; Comparacao entre metodos de fixacao do iodo radioativo em substrato de prata para confeccao de fontes utilizadas em braquiterapia

    Souza, Carla Daruich

    2012-07-01

    Among the different ways to treat prostate cancer, brachytherapy with iodine- 125 seeds is an option that provides good results and fewer side effects. In the present study several deposition methods of radioactive iodine in a silver substrate were compared in order to choose the most suitable alternative for the routine production to be implemented at IPEN's laboratory. The methodology used was chosen based on the available infrastructure and experience of the researchers present. Therefore, the {sup 131}I was used for testing (same chemical behavior as {sup 131}I). Four methods were selected: Method 1 (test based on electrodeposition method developed by D.Kubiatowicz) presented 65.16% efficiency; Method 2 (chemical reaction based on the method developed by D. Kubiatowicz - HCl) with the result of 70.80% efficiency; method 3 (chemical reaction based on the method developed by Dr. Maria Elisa Rostelato) with 55.80% efficiency; Method 4 (IQ-IPEN) resulted in 99% efficiency. Since this method has more radioactive material fixation (which represents virtually the entire cost of the seed), the final price is the cheapest. This method is the suggested one to be implemented in the IPEN's laboratory for brachytherapy sources production. Besides, the method is the fasted one. (author)

  12. Retrospective Analysis of Local Control and Cosmetic Outcome of 147 Periorificial Carcinomas of the Face Treated With Low-Dose Rate Interstitial Brachytherapy

    Purpose: Skin cancer is the most common malignancy in white populations. We evaluated the local cure rate and cosmetic outcome of patients with basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) of the face treated with low-dose rate brachytherapy. Methods and Materials: Between February 1990 and May 2000, 147 facial carcinomas in 132 patients were treated by 192Ir wire implantation. Side effects of brachytherapy were noted. Follow-up was 2 years or more. Locoregional recurrence-free survival (LRFS) and overall survival were recorded. Group A included patients treated by primary brachytherapy, and Group B included those treated after recurrence. Results: A total of 121 carcinomas were BCCs (82.3%) and 26 were SCCs (17.7%); the median tumor size was 10 mm. Of the tumors, 86 (58.5%) were in men and 61 (41.5%) were in women; the median age was 71 years. Group A comprised 116 lesions (78.9%), and Group B, 31 (21.1%). There were 17 relapses (11.6%) after a median follow-up of 72 months: 12 local, 4 nodal, and 1 local and nodal. Locoregional-free survival was 96.6% at 2 years and 87.3% at 5 years. Five-year LRFS was 82.6% in men and 93.3% in women (p = 0.027). After adjustment for gender, LRFS was better after primary treatment than after recurrence (hasard ratio HR, 2.91; 95% confidence interval, 1.06-8.03; p = 0.039). Five-year LRFS was 90.4% for BCC and 70.8% for SCC (p = 0.03). There were no Grade 3 complications. Conclusions: Low-dose rate brachytherapy offers good local control and cosmetic outcome in patients with periorificial skin carcinomas, with no Grade 3 complications. Brchytherapy is more efficient when used as primary treatment.

  13. 1979 Los Angeles accident: exposure to iridium 192 industrial radiographic source

    Eleven engineering plant employees were exposed to a 28-curie 192Ir industrial radiographic source that inadvertently had been left on the floor of the plant by a radiographer. One workman suffered a severe burn on his buttock, two workers developed radiation burns on their fingers, while acute anxiety and emotional disturbances were a prominent reaction of exposed individuals. Clinical observations, radiation dosimetry and depth-dose estimates, hematologic and cytogenetic studies are discussed for the exposed personnel

  14. Verification and analysis of the positioning of a source of brachytherapy high dose within an applicator gynecological interstitial fletcher Utrecht TC/RM; Verificacion y analysis del posicionamiento de una fuente de braquiterapia de alta tasa de dosis dentro de un aplicador ginecologico fletcher intersticial UTRECHT TC/RM

    Panedo Cobos, J. M.; Garcia castejon, M. A.; Huertas Martinez, C.; Gomez-Tejedor Alonso, S.; Rincon Perez, M.; Luna Tirado, J.; Perez Casas, A. M.

    2013-07-01

    Applicators are guides that circulate and are located within the patient brachytherapy sources. Applicators can suffer mechanical deformations due to processes of sterilization or shock, which may result in that the source do not place within these very precise and coincides with the planned. In these cases the planned treatment deviate actually managed. The object of this study is to verify that the position of the source into the dispenser coincides with the planned position, with a procedure that is described. (Author)

  15. Estimate of production of medical isotopes by photo-neutron reaction at the Canadian Light Source

    In contrast to conventional bremsstrahlung photon beam sources, laser backscatter photon sources at electron synchrotrons provide the capability to selectively tune photons to energies of interest. This feature, coupled with the ubiquitous giant dipole resonance excitations of atomic nuclei, promises a fertile method of nuclear isotope production. In this article, we present the results of simulations of production of the medical/industrial isotopes 196Au, 192Ir and 99Mo by (γ,n) reactions. We employ FLUKA Monte Carlo code along with the simulated photon flux for a beamline at the Canadian Light Source in conjunction with a CO2 laser system. -- Highlights: •We estimate production of medical isotopes by photo-neutron reaction. •Recently developed simulation code for generating laser backscattering photons at the CLS storage ring is described and used. •We describe the preliminary Monte Carlo simulations (using FLUKA code) for the production of 99Mo, 196Au and 192Ir isotopes. •The simulations demonstrate that the medical isotopes 99Mo, 192Ir and 196Au are the main products of photonuclear reaction on 100Mo, 193Ir and 197Au targets. •The present results agree with the evaluated and observed radioactive isotope production rates in RPIT experiment

  16. American Brachytherapy Society (ABS) recommendations for transperineal permanent brachytherapy of prostate cancer

    Purpose/Objective: To develop and disseminate the American Brachytherapy Society (ABS) recommendations for the clinical quality assurance and guidelines of permanent transperineal prostate brachytherapy with 125I or 103Pd. Methods and Materials: The ABS formed a committee of experts in prostate brachytherapy to develop consensus guidelines through a critical analysis of published data supplemented by their clinical experience. The recommendations of the panels were reviewed and approved by the Board of Directors of the ABS. Results: Patients with high probability of organ-confined disease are appropriately treated with brachytherapy alone. Brachytherapy candidates with a significant risk of extraprostatic extension should be treated with supplemental external beam radiation therapy (EBRT). Patient selection guidelines were developed. Dosimetric planning of the implant should be carried out for all patients before seed insertion. A modified peripheral loading is preferred. The AAPM TG-43 recommendations requiring a change in prescription dose for 125I sources should be universally implemented. The recommended prescription doses for monotherapy are 145 Gy for 125I and 115-120 Gy for 103Pd. The corresponding boost doses (after 40-50 Gy EBRT) are 100-110 Gy and 80-90 Gy, respectively. Clinical evidence to guide selection of radionuclide (103Pd or 125I) is lacking. Post implant dosimetry and evaluation must be performed on all patients. It is suggested that the dose that covers 90% (D90) and 100% (D100) of the prostate volume and the percentage of the prostate volume receiving the prescribed dose (V100) be obtained from a dose-volume histogram (DVH) and reported. Conclusion: Guidelines for appropriate patient selection, dose reporting, and improved quality of permanent prostate brachytherapy are presented. These broad recommendations are intended to be technical and advisory in nature, but the ultimate responsibility for the medical decisions rests with the treating

  17. Restenosis: Intracoronary Brachytherapy.

    Drachman, Douglas E.; Simon, Daniel I.

    2002-04-01

    Though interventional strategies have revolutionized the management of patients with symptomatic coronary artery disease, in-stent restenosis has emerged as the single most important limitation of long-term success following percutaneous coronary intervention. Once present, in-stent restenosis is extraordinarily difficult to treat, with conventional revascularization techniques failing in 50% to 80% of patients. Intracoronary radiation, or brachytherapy, targets cellular proliferation within the culprit neointima. Clinical trials have demonstrated that brachytherapy is a highly effective treatment for in-stent restenosis, reducing angiographic restenosis by 50% to 60% and the need for target vessel revascularization by 40% to 50%. The benefits of intracoronary brachytherapy may be particularly pronounced in certain patient subgroups (eg, those with diabetes, long lesions, or lesions in saphenous vein bypass grafts), but comes at the cost of an increased rate of late stent thrombosis and the need for extended antiplatelet therapy. The role of brachytherapy in the arsenal of the interventional cardiologist will continue to evolve, particularly in light of the unprecedented recent advances with the use of drug-eluting stents for restenosis prevention. PMID:11858773

  18. Determination of the dose around an ovoid for treatments in intracavitary brachytherapy Hdr; Determinacion de la dosis alrededor de un ovoide para tratamientos en braquiterapia intracavitaria HDR

    Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Legaria No. 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Velasco V, R. A. E. [Hospital Central Militar, Periferico y Ejercito Nacional s/n, Lomas de Sotelo, 11200 Mexico D. F. (Mexico); Serrano F, A. K. [Hospital Juarez de Mexico, Av. Instituto Politecnico Nacional No. 5190, Col. Magdalena de las Salinas, 03220 Mexico D. F. (Mexico); Azorin N, J., E-mail: trivera@ipn.m [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)

    2010-09-15

    On this work the results of the dosimetric measurements are presented around an ovoid of 2 cm diameter. The measurements were carried out using a water mannequin, an ovoid, a radiation gamma source of {sup 192}Ir and thermoluminescent dosemeters. The dosimetry was realized in the direction of the rectum and bladder. To know the effect of the shielding of the devices type Manchester in the dose, the thermoluminescent dosemeters were irradiated to a radiation gamma source of {sup 192}Ir contained in the Gamma med Plus equipment. The planning was realized normalizing the calculation to 2.5 cm from the applicator center on the transverse plane (2.5, 0, 0). The results show that the dose distribution for an ovoid without shielding is more uniform in the transversal plane to the source axis. The results were compared with the calculated results by means of the planning system BrachyVision. While the absorbed dose distribution around an ovoid with shielding is completely anisotropic. This anisotropic is due to the shielding. (Author)

  19. Magnetite nanoparticles for nonradionuclide brachytherapy1

    Safronov, Victor; Sozontov, Evgeny; Polikarpov, Mikhail

    2015-01-01

    Magnetite nanoparticles possess several properties that can make them useful for targeted delivery of radiation to tumors for the purpose of brachytherapy. Such particles are biodegradable and magnetic and can emit secondary radiation when irradiated by an external source. In this work, the dose distribution around a magnetite particle of 10 nm diameter being irradiated by monochromatic X-rays with energies in the range 4–60 keV is calculated.

  20. Development of a Brachytherapy Software Nomogram Equivalent

    The main objective of this project is developing a software nomogram equivalent. A nomogram is a graph typically comprised of three parallel lines. Each of the lines is graduated for a different variable, often in a non-linear scale. The lines are oriented in such a manner that if a straight line is drawn connecting two of the three variables, the value of the third variable is uniquely determined by the intersection of the connecting line and the graduated line of the third variable. The value of the third variable is determined by reading the graduated scale at the point of intersection. A nomogram as applied in brachytherapy is used for determining the required amount of radioactive material to be implanted in a diseased site. A typical brachytherapy nomogram relates the average dimension of a site, the air kerma strength per source and the number of sources required for yielding a therapeutic radiation dose to the site. More sophisticated nomograms also provide scales for recommending source and needle spacings. For decades the nomogram has been clinically employed as a brachytherapy treatment planning tool. Imaging modalities such as CT and ultrasound ushered in modern image-based brachytherapy treatment planning. These modern imaging techniques dramatically advanced the state of the art of brachytherapy, often obviating the use of nomograms. Although the routine use of nomograms has decreased, there are clinical situations where nomograms still prove useful for brachytherapy treatment planning. Often times the dimensions of a tumor or tumor bed are not known prior to surgery and delineated images of the site are not available. In such situations the tumor dimensions can be measured in the OR and a nomogram applied for rapid treatment planning. By definition a nomogram is a graphical tool, which is fixed and cannot be modified. Differences of opinion and treatment philosophies exist among physicians and institutions. These varying approaches can lead to

  1. Development of a multi-electrode extrapolation chamber as a prototype of a primary standard for the realization of the unit of the absorbed dose to water for beta brachytherapy sources

    Bambynek, M

    2002-01-01

    The prototype of a primary standard has been developed, built and tested, which enables the realization of the unit of the absorbed dose to water for beta brachytherapy sources. In the course of the development of the prototype, the recommendations of the American Association of Physicists in Medicine (AAPM) Task Group 60 (TG60) and the Deutsche Gesellschaft fuer Medizinische Physik (DGMP) Arbeitskreis 18 (AK18) were taken into account. The prototype is based on a new multi-electrode extrapolation chamber (MEC) which meets, in particular, the requirements on high spatial resolution and small uncertainty. The central part of the MEC is a segmented collecting electrode which was manufactured in the clean room center of PTB by means of electron beam lithography on a wafer. A precise displacement device consisting of three piezoelectric macrotranslators has been incorporated to move the wafer collecting electrode against the entrance window. For adjustment of the wafer collecting electrode parallel to the entranc...

  2. Imaging method for monitoring delivery of high dose rate brachytherapy

    Weisenberger, Andrew G; Majewski, Stanislaw

    2012-10-23

    A method for in-situ monitoring both the balloon/cavity and the radioactive source in brachytherapy treatment utilizing using at least one pair of miniature gamma cameras to acquire separate images of: 1) the radioactive source as it is moved in the tumor volume during brachytherapy; and 2) a relatively low intensity radiation source produced by either an injected radiopharmaceutical rendering cancerous tissue visible or from a radioactive solution filling a balloon surgically implanted into the cavity formed by the surgical resection of a tumor.

  3. Radiochromic dye film studies for brachytherapy applications.

    Martínez-Dávalos, A; Rodríguez-Villafuerte, M; Díaz-Perches, R; Arzamendi-Pérez, S

    2002-01-01

    Commercial radiochromic dye films have been used in recent years to quantify absorbed dose in several medical applications. In this study we present the characterisation of the GafChromic MD-55-2 dye film, a double sensitive layer film suitable for photon irradiation in brachytherapy applications. Dose measurements were carried out with a low dose rate 137Cs brachytherapy source, which produces very steep dose gradients in its vicinity, and therefore requires the capability of producing high spatial resolution isodose curves. Quantification of the dose rate in water per unit air kerma strength was obtained using a high-resolution transmission commercial scanner (Agfa DuoScan T1200 with the capability of digitising up to 600 x 1200 pixels per inch using 36 bits per pixel, together with optical density measurements. The Monte Carlo calculations and experimental measurements compared well in the 0-50 Gy dose interval used in this study. PMID:12382798

  4. Radiochromic dye film studies for brachytherapy applications

    Martinez-Davalos, A.; Rodriguez-Villafuerte, M.; Diaz-Perches, R.; Arzamendi-Perez, S

    2002-07-01

    Commercial radiochromic dye films have been used in recent years to quantify absorbed dose in several medical applications. In this study we present the characterisation of the GafChromic MD-55-2 dye film, a double sensitive layer film suitable for photon irradiation in brachytherapy applications. Dose measurements were carried out with a low dose rate {sup 137}Cs brachytherapy source, which produces very steep dose gradients in its vicinity, and therefore requires the capability of producing high spatial resolution isodose curves. Quantification of the dose rate in water per unit air kerma strength was obtained using a high-resolution transmission commercial scanner (Agfa DuoScan T1200) with the capability of digitising up to 600 x 1200 pixels per inch using 36 bits per pixel, together with optical density measurements. The Monte Carlo calculations and experimental measurements compared well in the 0-50 Gy dose interval used in this study. (author)

  5. Radiochromic dye film studies for brachytherapy applications

    Commercial radiochromic dye films have been used in recent years to quantify absorbed dose in several medical applications. In this study we present the characterisation of the GafChromic MD-55-2 dye film, a double sensitive layer film suitable for photon irradiation in brachytherapy applications. Dose measurements were carried out with a low dose rate 137Cs brachytherapy source, which produces very steep dose gradients in its vicinity, and therefore requires the capability of producing high spatial resolution isodose curves. Quantification of the dose rate in water per unit air kerma strength was obtained using a high-resolution transmission commercial scanner (Agfa DuoScan T1200) with the capability of digitising up to 600 x 1200 pixels per inch using 36 bits per pixel, together with optical density measurements. The Monte Carlo calculations and experimental measurements compared well in the 0-50 Gy dose interval used in this study. (author)

  6. The evolution of brachytherapy treatment planning

    Brachytherapy is a mature treatment modality that has benefited from technological advances. Treatment planning has advanced from simple lookup tables to complex, computer-based dose-calculation algorithms. The current approach is based on the AAPM TG-43 formalism with recent advances in acquiring single-source dose distributions. However, this formalism has clinically relevant limitations for calculating patient dose. Dose-calculation algorithms are being developed based on Monte Carlo methods, collapsed cone, and solving the linear Boltzmann transport equation. In addition to improved dose-calculation tools, planning systems and brachytherapy treatment planning will account for material heterogeneities, scatter conditions, radiobiology, and image guidance. The AAPM, ESTRO, and other professional societies are working to coordinate clinical integration of these advancements. This Vision 20/20 article provides insight into these endeavors.

  7. The evolution of brachytherapy treatment planning

    Rivard, Mark J.; Venselaar, Jack L. M.; Beaulieu, Luc [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Medical Physics, Instituut Verbeeten, P.O. Box 90120, 5000 LA Tilburg (Netherlands); Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de l' Universite Laval, Centre Hospitalier Universitaire de Quebec, 11 Cote du Palais, Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d' Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada)

    2009-06-15

    Brachytherapy is a mature treatment modality that has benefited from technological advances. Treatment planning has advanced from simple lookup tables to complex, computer-based dose-calculation algorithms. The current approach is based on the AAPM TG-43 formalism with recent advances in acquiring single-source dose distributions. However, this formalism has clinically relevant limitations for calculating patient dose. Dose-calculation algorithms are being developed based on Monte Carlo methods, collapsed cone, and solving the linear Boltzmann transport equation. In addition to improved dose-calculation tools, planning systems and brachytherapy treatment planning will account for material heterogeneities, scatter conditions, radiobiology, and image guidance. The AAPM, ESTRO, and other professional societies are working to coordinate clinical integration of these advancements. This Vision 20/20 article provides insight into these endeavors.

  8. An investigation of a PRESAGE® in vivo dosimeter for brachytherapy

    Vidovic, A. K.; Juang, T.; Meltsner, S.; Adamovics, J.; Chino, J.; Steffey, B.; Craciunescu, O.; Oldham, M.

    2014-07-01

    Determining accurate in vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm × 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® in vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with a commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0-15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy ṡ cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (˜1 mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in vivo dose verification

  9. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy; Preparacion y determinacion del kerma de fuentes de iridio-192 de baja tasa de dosis para braquiterapia

    Tendilla, J.I.; Tovar M, V.; Mitsoura, E.; Aguilar H, F.; Alanis M, J. [Instituto Nacional de Investigaciones Nucleares, C.P. 52045-1, Salazar, Esrado de Mexico, D.F. (Mexico)

    2000-07-01

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 {+-} 0.531 M Bq and kerma in air 0.03200 {+-} 0.00006 m Gy m/h A. (Author)

  10. Glass microspheres for brachytherapy

    We developed the capacity to produce glass microspheres containing in their structure one or more radioactive isotopes useful for brachytherapy. We studied the various facts related with their production: (Rare earth) alumino silicate glass making, glass characterization, microspheres production, nuclear activation through (n,γ) nuclear reactions, mechanical characterization before and after irradiation. Corrosion tests in simulated human plasma and mechanical properties characterization were done before and after irradiation. (author)

  11. An analysis of acute complications and perioperative morbidity from high dose rate brachytherapy in the treatment of gynecological malignancies

    Purpose: To evaluate the acute morbidity and mortality for high dose-rate (HDR) brachytherapy performed in an outpatient setting in the treatment of gynecological malignancies, and to identify possible risk factors for adverse outcomes. Materials and Methods: One hundred seventy-one patients with cervical (n=129) or uterine (n=42) carcinoma with an intact uterus were evaluated and treated from August 1989 through December 1994, with at least part of their therapy delivered with intracavitary HDR 192Ir radiation. A total of 830 ICR insertions were performed with greater than 95% done on an outpatient basis under heavy intravenous sedation using fentanyl and midazolam. Perioperative morbidity and mortality were recorded for any event occurring within 30 days of the completion of therapy. Anesthesia risk was evaluated retrospectively in all patients based on the American Society of Anesthesiologists' (ASA) Physical Class System. Results: The uterine patients, many treated with radiation alone because of morbid obesity or medical inoperability, had a significantly higher perioperative morbidity and mortality rate as compared to the cervix patient cohort. Thirteen of the 42 (31%) uterine patients and 8 of the 129 (6%) cervix patients required hospitalization within 30 days of treatment completion (p2) experienced greater morbidity and mortality, while the best predictor of complications in the cervix patients was age greater than 70 years. For the entire cohort of patients, no correlation was found between the 30 day morbidity and mortality and the doses of fentanyl and midazolam used or the length of the procedure. Conclusions: The acute complication rate from HDR brachytherapy performed on an outpatient basis with heavy intravenous sedation is acceptable for the great majority of patients who present for treatment. However, the high morbidity and mortality experienced by certain patient cohorts suggests that careful assessment of the risk/benefit ratio for treatment

  12. A Multi-Institutional Study of Feasibility, Implementation, and Early Clinical Results With Noninvasive Breast Brachytherapy for Tumor Bed Boost

    Purpose: To evaluate the feasibility, implementation, and early results of noninvasive breast brachytherapy (NIBB) for tumor bed boost with whole breast radiation therapy (WBRT). Methods and Materials: NIBB is a commercially available (AccuBoost, Billerica, MA) mammography-based, brachytherapy system in which the treatment applicators are centered on the planning target volume (PTV) to direct 192Ir emissions along orthogonal axes. A privacy-encrypted online data registry collected information from 8 independent academic and community-based institutions. Data were from 146 consecutive women with early-stage breast cancer after lumpectomy and WBRT receiving boost with NIBB between July 2007 and March 2010. Toxicity and cosmesis were graded according to the Common Toxicity Criteria (v. 3.0) and the Harvard scale. Median follow-up was 6 months (1–39 months). Results: Grade 1–2 skin toxicity was observed in 64%, 48%, and 21% during the acute (1–3 weeks), intermediate (4–26 weeks), and late-intermediate (>26 weeks) periods. There was no Grade 4 toxicity. At 6 months, for the entire cohort, cosmesis was excellent/good in 62%/38%. The subset receiving NIBB before WBRT had cosmetic scores of 32% and 63%, whereas during WBRT, 58% and 37% were rated as excellent and good, respectively. Breast compression was scored as “uncomfortable” in 12%, 29%, and 59% when NIBB was delivered before, during, or after WBRT. For each patient, the fraction-to-fraction variability in PTV was low. Skin flash was associated with a higher proportion of excellent cosmesis (58% vs. 42%) relative to having the applicator all within breast tissue. Conclusions: These data indicate that NIBB is feasible and can be consistently implemented in a broad array of practice settings. Preliminary evaluation suggests that NIBB is associated with acceptably mild normal tissue toxicity and favorable early cosmesis. The application of NIBB before WBRT may be associated with better patient tolerance at

  13. Dosimetric calculus in intravascular brachytherapy

    Among the cardiovascular diseases, the most common is acute myocardial infarction, which occurs because of the occlusion of one or more coronary arteries. Balloon angioplasty has been a popular treatment which is less invasive than surgeries involving revascularization of the myocardium, thus promising a better quality of life for patients. Unfortunately, the rate of restenosis (re-closing of the vessel) after balloon angioplasty is high (approximately 30-50% within the first year after treatment). Known as Intravascular Brachytherapy, the technique has been used with several radiation sources, and researchers have obtained success in decreasing the rate of restenosis. In order to study the radiation dosimetry in the patient and radiological protection for this therapy, radiation dose distributions for monoenergetic electrons and photons (at nine discrete energies) were calculated for blood vessels of diameter 0.15, 0.30 and 0.45 cm with balloon and wire sources using the radiation transport code MCNP4B. Specific calculations were carried out for several radionuclides. Two stent sources employing 32P are also simulated. Advantages and disadvantages of the radionuclides and source geometries are discussed and the dosimetry developed here will aid in the realization of the benefits obtained in patients. (author)

  14. Prospective randomised trial on the role of HDR-brachytherapy in addition to external beam radiotherapy for central bronchial carcinoma

    Objective: In a prospective, randomised trial we investigated the influence of additional High-Dose-Rate-(HDR)-brachytherapy on tumor control and overall survival of patients suffering from inoperable central lung tumors treated with loco-regional external beam radiotherapy (EB-RT). Special attention was given to dose limiting side effects. Methods: Patients randomised in group A received loco-regional EB-RT up to 50 Gy (5 x 2 Gy per week), followed by a boost of 10 Gy also 2 Gy 5 times a week to the primary and adjacent lymphonodular metastases. Patients in group B additionally received an endoluminal HDR-afterloading-radiotherapy (192Ir) with 10 Gy calculated for 5 mm depth one week before and three weeks after EB-RT. Due to the advanced tumor stage, none of the patients received surgery before irradiation. Patients treated with chemotherapy were excluded from the study. Results: Until February 1996 all of 98 patients were evaluated. Both groups are comparable regarding age, gender, Karnofsky Performance State, tumor stage (mostly stage IIIb and IV) and histology. Squamous cell carcinoma (SCC) were found in 69%, whereas the rest consisted of adeno carcinoma (15%), large cell carcinoma (6%) and non small cell carcinoma (NSCLC) (10%), all subsets equally distributed between group A and B. Local control in group A (n=42) lasted for a median of 12 weeks, in group B (n=56) for a median of 21 weeks, a difference which is just significant (p≤0,05). The median overall survival was nearly identical (28 weeks). The subgroup of SCC, however, showed a median survival of 33 (group A) versus 40 weeks (group B), a difference which is not significant (p≤0.09), but might indicate an advantage for this histological group. The most serious side effect was fatal bleeding with 15% in group A and 21% in group B. Conclusions: At present, this study reveals improved local control by a boost of 2x10 Gy 192Ir-HDR-AL in addition to definitive EB-RT (group B) compared to EB-RT alone

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

    Andersen, Claus E.; Nielsen, Soeren Kynde; Lindegaard, Jacob Christian; Tanderup, Kari [Radiation Research Division, Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Department of Medical Physics, Aarhus University Hospital, DK-8000 Aarhus C (Denmark); Department of Oncology, Aarhus University Hospital, DK-8000 Aarhus C (Denmark); Department of Medical Physics, Aarhus University Hospital, DK-8000 Aarhus C (Denmark)

    2009-11-15

    Purpose: 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. Methods: Five cervix cancer patients undergoing PDR brachytherapy (Varian GammaMed Plus with {sup 192}Ir) 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. Results: 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

  16. Nodal recurrences after exclusive brachytherapy for T1-T2 N0 cancer of the oral tongue

    INTRODUCTION: Exclusive brachytherapy represents the treatment of choice in small volume cancer of the oral tongue. In this neoplasm however the incidence of subclinical metastasis in neck nodes is not negligible, and prophylactic neck dissection is advocated by some Authors after interstitial irradiation. We have thus reviewed the incidence of nodal recurrences in a group of pts treated with brachytherapy alone for tongue cancer. PATIENTS METHODS AND RESULTS: From 1982 to 1994 44 pts (27 males, 17 females, age 35-84 years, median 63,3 years) were treated with 192 Ir interstitial irradiation alone for clinically N0 epidermoid cancer of the oral tongue (T1: 19 pts, T2: 25 pts). Brachytherapy was performed with hairpins or plastic tubes, according to the rules of the Paris system. Dose ranged from 60-70 Gy with a dose rate of 0.38-0.62 Gy/h (median: 63.8 and 0.52 respectively). Local recurrences were observed in 8 pts (18.1 %), 3 of whom are free from disease after salvage surgery. Neck nodes metastasis appeared after 3-11 months (mos) from primary treatment (median 6,3 mos) and represented the first site of failure in 16 pts (36,3 %; T1 (6(19)): 31,5 %. T2(10(25)) : 40 %; volume 3cc.: 55.5 %). After neck dissection and external radiotherapy 10 of them were rendered free from disease and are still alive at 12-123 mos. Definitive control above the clavicles was thus 75 % ((33(44)) pts). DISCUSSION AND CONCLUSION: Exclusive brachytherapy can obtain excellent local control rates in T1 T2 oral tongue cancer (81.9 % in our experience). Nodal recurrences are however frequent after interstitial irradiation in large volume cancers and salvage of pts relapsed in the neck is not easily achievable. Prophylactic neck dissection could be advisable to enhance regional control rate in these pts. The role of newer methods to evaluate neck nodes during follow up (ultrasonography and fine needle aspiration of suspicious nodes) is now being investigated in our centre

  17. Salvage Brachytherapy for Biochemically Recurrent Prostate Cancer following Primary Brachytherapy

    Lacy, John M.; Wilson, William A.; Bole, Raevti; Chen, Li; Meigooni, Ali S.; Rowland, Randall G.; Clair, William H. St.

    2016-01-01

    Purpose. In this study, we evaluated our experience with salvage brachytherapy after discovery of biochemical recurrence after a prior brachytherapy procedure. Methods and Materials. From 2001 through 2012 twenty-one patients treated by brachytherapy within University of Kentucky or from outside centers developed biochemical failure and had no evidence of metastases. Computed tomography (CT) scans were evaluated; patients who had an underseeded portion of their prostate were considered for reimplantation. Results. The majority of the patients in this study (61.9%) were low risk and median presalvage PSA was 3.49 (range 17.41–1.68). Mean follow-up was 61 months. At last follow-up after reseeding, 11/21 (52.4%) were free of biochemical recurrence. There was a trend towards decreased freedom from biochemical recurrence in low risk patients (p = 0.12). International Prostate Symptom Scores (IPSS) increased at 3-month follow-up visits but decreased and were equivalent to baseline scores at 18 months. Conclusions. Salvage brachytherapy after primary brachytherapy is possible; however, in our experience the side-effect profile after the second brachytherapy procedure was higher than after the first brachytherapy procedure. In this cohort of patients we demonstrate that approximately 50% oncologic control, low risk patients appear to have better outcomes than others. PMID:27092279

  18. Production of sealed sup 6 sup 0 Co and sup 1 sup 9 sup 2 Ir sources of high specific activity in the nuclear reactor RA

    Given is a review on the development of the production of 60 Co and 192 Ir performed in the Vinca Institute in the nuclear reactor RA. The experience gained showed that this reactor was suitable for obtaining of these and some other radionuclides. One possibility of its re-start is that the performances of the reactor remain the same (power 6.5 MW, max.neutron flux up to 6x10 13 n.cm-2 s-1). By applying new techniques of target preparation, 60 Co for sterilization units of specific activity 1.11 TBq/g could be produced. Maximal activity of sup 1 sup 9 sup 2 Ir would be about 1.48 TBq what is satisfactory for the sources for gamma radiography. The increase of the flux to 1014 n.cm-2 s -1 would enable the production of 60 Co of specific activities about 3.335 TBq/g. This is satisfactory for the sources for the radiation therapy of activities up to 111 TBq and for gamma radiography of activities about 0.37 TBq. In the case of 192 Ir the sources for the radiation therapy of activities about 0.37 TBq could be obtained. Maximal achievable activities of 192 Ir would be about 3.7 TBq. (author)

  19. Treatment outcome with low-dose-rate interstitial brachytherapy in early-stage oral tongue cancers

    Bhalavat Rajendra

    2009-01-01

    Full Text Available Purpose : Although radical radiotherapy is known to be equally effective for early-stage oral tongue cancers (T1-2 N0 with the added advantage of organ and function preservation, surgery remains the preferred treatment. We present outcome of patients treated with brachytherapy (BT either radical or boost. Materials and Methods : Fifty-seven patients (T1/T2 31/26 were studied. Seventeen patients (30% were treated with radical BT (50-67 Gy while 40 (70% with external beam radiation therapy (EBRT + BT (36-56 Gy + 15-38 Gy]. Low-dose-rate (LDR BT was delivered with 192 Ir wires, using plastic bead technique with varied dose rates (< 60 cGy/h in 29 patients, 60-90 cGy/h in 17, and> 90 cGy/h in 11. Results : The overall local control (LCR was achieved in 59.7% (34/57 patients. LCR for T1 and T2 was 67.8% and 50%, respectively. A total of 23 patients had failures [local: 20 (T1: 8; T2: 12 patients, node: 5 (T1:2; T2: 3, and local + nodal: 3]. Overall 5-year disease-free survival and overall survival (OAS were 51% and 67%, respectively and those for T1 and T2 was 64.5/77.4% and 38.5/54% respectively (P = 0.002. All 16 patients were salvaged. Median survival after salvage treatment was 13.5 months (6-100 months. Soft tissue necrosis was observed in 12.3% (7/57 and osteoradionecrosis in two patients. Conclusion : BT, as an integral part of radical radiation therapy in early-stage tongue cancers, appears to be an effective alternative treatment modality with preservation of the organ and function without jeopardizing the outcome.

  20. Postal auditing methodology used to find out the performance of high rate brachytherapy equipment

    This work describes results from a methodology implemented at the Secondary Laboratory for Dosimetric Calibration at CPHR used to check the brachytherapy performance at high doses rate using Cesium 137 or cobalt 60 sources

  1. Sealed source and device design safety testing: Technical report on the findings of task 4 -- Investigation of failed Nitinol brachytherapy wire. Volume 2

    Benac, D.J.; Burghard, H.C. [Southwest Research Inst., San Antonio, TX (United States)

    1996-03-01

    This report covers an investigation of the nature and cause of failure in Nitinol brachytherapy sourcewires. The investigation was initiated after two clinical incidents in which sourcewires failed during or immediately after a treatment. The investigation determined that the two clinical Nitinol sourcewires failed in a brittle manner, which is atypical for Nitinol. There were no material anomalies or subcritical flaws to explain the brittle failures. The bend tests also demonstrated that neither moist environment, radiation, nor low-temperature structural transformation was a likely root cause of the failures. However, degradation of the PTFE was consistently evident, and those sourcewires shipped or stored with PTFE sleeves consistently failed in laboratory bend tests. On the basis of the results of this study, it was concluded that the root cause of the in-service failures of the sourcewires was environmentally induced embrittlement due to the breakdown of the PTFE protective sleeves in the presence of the high-radiation field and subsequent reaction or interaction of the breakdown products with the Nitinol alloy.

  2. Sealed source and device design safety testing: Technical report on the findings of task 4 -- Investigation of failed Nitinol brachytherapy wire. Volume 2

    This report covers an investigation of the nature and cause of failure in Nitinol brachytherapy sourcewires. The investigation was initiated after two clinical incidents in which sourcewires failed during or immediately after a treatment. The investigation determined that the two clinical Nitinol sourcewires failed in a brittle manner, which is atypical for Nitinol. There were no material anomalies or subcritical flaws to explain the brittle failures. The bend tests also demonstrated that neither moist environment, radiation, nor low-temperature structural transformation was a likely root cause of the failures. However, degradation of the PTFE was consistently evident, and those sourcewires shipped or stored with PTFE sleeves consistently failed in laboratory bend tests. On the basis of the results of this study, it was concluded that the root cause of the in-service failures of the sourcewires was environmentally induced embrittlement due to the breakdown of the PTFE protective sleeves in the presence of the high-radiation field and subsequent reaction or interaction of the breakdown products with the Nitinol alloy

  3. 106Ruthenium Brachytherapy for Retinoblastoma

    Purpose: To evaluate the efficacy of 106Ru plaque brachytherapy for the treatment of retinoblastoma. Methods and Materials: We reviewed a retrospective, noncomparative case series of 39 children with retinoblastoma treated with 106Ru plaques at the Jules-Gonin Eye Hospital between October 1992 and July 2006, with 12 months of follow-up. Results: A total of 63 tumors were treated with 106Ru brachytherapy in 41 eyes. The median patient age was 27 months. 106Ru brachytherapy was the first-line treatment for 3 tumors (4.8%), second-line treatment for 13 (20.6%), and salvage treatment for 47 tumors (74.6%) resistant to other treatment modalities. Overall tumor control was achieved in 73% at 1 year. Tumor recurrence at 12 months was observed in 2 (12.5%) of 16 tumors for which 106Ru brachytherapy was used as the first- or second-line treatment and in 15 (31.9%) of 47 tumors for which 106Ru brachytherapy was used as salvage treatment. Eye retention was achieved in 76% of cases (31 of 41 eyes). Univariate and multivariate analyses revealed no statistically significant risk factors for tumor recurrence. Radiation complications included retinal detachment in 7 (17.1%), proliferative retinopathy in 1 (2.4%), and subcapsular cataract in 4 (9.7%) of 41 eyes. Conclusion: 106Ru brachytherapy is an effective treatment for retinoblastoma, with few secondary complications. Local vitreous seeding can be successfully treated with 106Ru brachytherapy

  4. Validation of GPUMCD for low-energy brachytherapy seed dosimetry

    Hissoiny, Sami; Ozell, Benoit; Despres, Philippe; Carrier, Jean-Francois [Ecole polytechnique de Montreal, Departement de genie informatique et genie logiciel, 2500 chemin de Polytechnique, Montreal, QC, H3T 1J4 (Canada); Departement de radio-oncologie, Centre hospitalier universitaire de Quebec (CHUQ), 11 Cote du Palais, Quebec, QC, G1R 2J6 (Canada); Departement de physique, Universite de Montreal, Montreal, QC (Canada) and Departement de radio-oncologie and Centre de recherche du CHUM, Centre hospitalier de l' Universite de Montreal (CHUM), Montreal, QC, H2L 4M1 (Canada)

    2011-07-15

    Purpose: To validate GPUMCD, a new package for fast Monte Carlo dose calculations based on the GPU (graphics processing unit), as a tool for low-energy single seed brachytherapy dosimetry for specific seed models. As the currently accepted method of dose calculation in low-energy brachytherapy computations relies on severe approximations, a Monte Carlo based approach would result in more accurate dose calculations, taking in to consideration the patient anatomy as well as interseed attenuation. The first step is to evaluate the capability of GPUMCD to reproduce low-energy, single source, brachytherapy calculations which could ultimately result in fast and accurate, Monte Carlo based, brachytherapy dose calculations for routine planning. Methods: A mixed geometry engine was integrated to GPUMCD capable of handling parametric as well as voxelized geometries. In order to evaluate GPUMCD for brachytherapy calculations, several dosimetry parameters were computed and compared to values found in the literature. These parameters, defined by the AAPM Task-Group No. 43, are the radial dose function, the 2D anisotropy function, and the dose rate constant. These three parameters were computed for two different brachytherapy sources: the Amersham OncoSeed 6711 and the Imagyn IsoStar IS-12501. Results: GPUMCD was shown to yield dosimetric parameters similar to those found in the literature. It reproduces radial dose functions to within 1.25% for both sources in the 0.5< r <10 cm range. The 2D anisotropy function was found to be within 3% at r = 5 cm and within 4% at r = 1 cm. The dose rate constants obtained were within the range of other values reported in the literature.Conclusion: GPUMCD was shown to be able to reproduce various TG-43 parameters for two different low-energy brachytherapy sources found in the literature. The next step is to test GPUMCD as a fast clinical Monte Carlo brachytherapy dose calculations with multiple seeds and patient geometry, potentially providing

  5. The Activity Check of Brachytherapy Isotope

    An isotope Ir-192, which is used in brachytherapy depends on import in whole quantities. There are a few ways for its activity. measurement using Welltype chamber or the way to rely on authentic decay table of manufacturer. In-air dosimetry using Farmer Chamber, etc. In this paper, let me introduce the way using Farmer chamber which is easier and simple. With the Farmer chamber and source calibration jig, take a measurement the activity of an isotope Ir-192 and compare the value with the value from decay table of manufacturer and check the activity of source. The result of measurement, compared the value from decay table, by ±2.1. (which belongs to recommendable value for AAPM ±5% as difference of error range). It is possible to use on clinical medicine. With the increase in use of brachytherapy, the increase of import is essential. And an accurate activity check of source is compulsory. For the activity check of source, it was possible to use Farmer chamber and source calibration jig without additional purchase of Well type chamber.

  6. HDR neutron brachytherapy for prostatic cancer in lithuania

    The purpose of this report is to analyse the physical and radiobiological background of the HDR Cf-252 Neutron brachytherapy boost in the combined radiation therapy for locally advanced prostatic cancer. The treatment schedule:two fractions of the Cf-252 brachytherapy(5Gy-eq at the dose point 2 cm from source movement trajectory) with interval 24 hours; 5-8 fractions of the photon beam external radiation therapy(5 fractions per week, 2 Gy per fraction) to the prostate, two fractions of the Cf-252 brachytherapy and after that external beam radiation therapy is continued till total dose 40-45 Gy. Six patients completed the proposed combined radiation therapy. The results of this trial will be discussed

  7. Dose determination in breast tumor in brachytherapy using Iridium-192

    Thermoluminescent dosimetry studies in vivo and in vitro aiming to determing radiation dose in the breast tumor, in brachytherapy using Iridium-192 was done. The correlation between radiation doses in tumor and external surface of the breast was investigated for correcting the time interval of radiation source implantation. (author)

  8. Multihelix rotating shield brachytherapy for cervical cancer

    Purpose: To present a novel brachytherapy technique, called multihelix rotating shield brachytherapy (H-RSBT), for the precise angular and linear positioning of a partial shield in a curved applicator. H-RSBT mechanically enables the dose delivery using only linear translational motion of the radiation source/shield combination. The previously proposed approach of serial rotating shield brachytherapy (S-RSBT), in which the partial shield is rotated to several angular positions at each source dwell position [W. Yang et al., “Rotating-shield brachytherapy for cervical cancer,” Phys. Med. Biol. 58, 3931–3941 (2013)], is mechanically challenging to implement in a curved applicator, and H-RSBT is proposed as a feasible solution. Methods: A Henschke-type applicator, designed for an electronic brachytherapy source (Xoft Axxent™) and a 0.5 mm thick tungsten partial shield with 180° or 45° azimuthal emission angles and 116° asymmetric zenith angle, is proposed. The interior wall of the applicator contains six evenly spaced helical keyways that rigidly define the emission direction of the partial radiation shield as a function of depth in the applicator. The shield contains three uniformly distributed protruding keys on its exterior wall and is attached to the source such that it rotates freely, thus longitudinal translational motion of the source is transferred to rotational motion of the shield. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients with a diverse range of high-risk target volume (HR-CTV) shapes and applicator positions. For each patient, the total number of emission angles was held nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. Treatment delivery time and tumor coverage (D90 of HR-CTV) were the two metrics used as the basis for evaluation and

  9. Multihelix rotating shield brachytherapy for cervical cancer

    Dadkhah, Hossein [Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States); Kim, Yusung; Flynn, Ryan T., E-mail: ryan-flynn@uiowa.edu [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Wu, Xiaodong [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 and Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States)

    2015-11-15

    Purpose: To present a novel brachytherapy technique, called multihelix rotating shield brachytherapy (H-RSBT), for the precise angular and linear positioning of a partial shield in a curved applicator. H-RSBT mechanically enables the dose delivery using only linear translational motion of the radiation source/shield combination. The previously proposed approach of serial rotating shield brachytherapy (S-RSBT), in which the partial shield is rotated to several angular positions at each source dwell position [W. Yang et al., “Rotating-shield brachytherapy for cervical cancer,” Phys. Med. Biol. 58, 3931–3941 (2013)], is mechanically challenging to implement in a curved applicator, and H-RSBT is proposed as a feasible solution. Methods: A Henschke-type applicator, designed for an electronic brachytherapy source (Xoft Axxent™) and a 0.5 mm thick tungsten partial shield with 180° or 45° azimuthal emission angles and 116° asymmetric zenith angle, is proposed. The interior wall of the applicator contains six evenly spaced helical keyways that rigidly define the emission direction of the partial radiation shield as a function of depth in the applicator. The shield contains three uniformly distributed protruding keys on its exterior wall and is attached to the source such that it rotates freely, thus longitudinal translational motion of the source is transferred to rotational motion of the shield. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients with a diverse range of high-risk target volume (HR-CTV) shapes and applicator positions. For each patient, the total number of emission angles was held nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. Treatment delivery time and tumor coverage (D{sub 90} of HR-CTV) were the two metrics used as the basis for evaluation and

  10. Brachytherapy- past, present and future

    Discovery of radioactivity by Henry Becquerel and radium by Madame and Pierre Curie was probably the greatest event of 19th century in the field of medical science. Radium was used for brachytherapy as early as 1901. Today almost every organ is amenable to brachytherapy procedure. High dose rate remote afterloading systems have increased the patients comfort and complete radiation protection to the staff during treatment. Computers have not only improved the precision of treatment but also made 3 D conformal brachytherapy possible. As the goal of cancer management is changing from just life preservation to organ and function preservation without compromising cure rate, the role of brachytherapy is becoming more and more prominent. Intensive efforts will be needed to meet with the future challenges. (author). 13 refs

  11. Use of Monte Carlo Methods in brachytherapy; Uso del metodo de Monte Carlo en braquiterapia

    Granero Cabanero, D.

    2015-07-01

    The Monte Carlo method has become a fundamental tool for brachytherapy dosimetry mainly because no difficulties associated with experimental dosimetry. In brachytherapy the main handicap of experimental dosimetry is the high dose gradient near the present sources making small uncertainties in the positioning of the detectors lead to large uncertainties in the dose. This presentation will review mainly the procedure for calculating dose distributions around a fountain using the Monte Carlo method showing the difficulties inherent in these calculations. In addition we will briefly review other applications of the method of Monte Carlo in brachytherapy dosimetry, as its use in advanced calculation algorithms, calculating barriers or obtaining dose applicators around. (Author)

  12. Brachytherapy in childhood rhabdomyosarcoma treatment

    A retrospective study of 21 children with rhabdomyosarcoma treated by brachytherapy to the primary site of the tumor at the Radiotherapy Department of the A.C.Camargo Hospital between january/1980 to june/1993 was undertaken. The main objectives were to comprove the utility of brachytherapy in childhood rhabdomyosarcoma, to evaluate the local control and survival, in association with chemotherapy, to analyze the late effects of the treatment and to determinate the preferential technique to each clinical situation. All patients received brachytherapy to the tumor site. The radioactive isotopes employed were Gold198, Cesium137 and Iridium192. The brachytherapy techniques depended on the tumor site, period of treatment, availability of the radioactive material and stage of the disease. Patients treated exclusively by brachytherapy received 40 Gy to 60 Gy. When brachytherapy was associated with external radiotherapy the dose ranged from 20 Gy to 40 Gy. Local control was achieved in 18 of 20 patients (90%). The global survival and local control survival rates were 61.9% (13/21 patients) and 72,2% (13/18 patients) respectively. (author)

  13. Local anesthesia for prostate brachytherapy

    Purpose: To demonstrate the technique and feasibility of prostate brachytherapy performed with local anesthesia only. Methods and Materials: A 5 by 5 cm patch of perineal skin and subcutaneous tissue is anesthetized by local infiltration of 10 cc of 1% lidocaine with epinephrine, using a 25-gauge 5/8-inch needle. Immediately following injection into the subcutaneous tissues, the deeper tissues, including the pelvic floor and prostate apex, are anesthetized by injecting 15 cc lidocaine solution with approximately 8 passes of a 20-gauge 1.0-inch needle. Following subcutaneous and peri-apical lidocaine injections, the patient is brought to the simulator suite and placed in leg stirrups. The transrectal ultrasound (TRUS) probe is positioned to reproduce the planning images and a 3.5- or 6.0-inch, 22-gauge spinal needle is inserted into the peripheral planned needle tracks, monitored by TRUS. When the tips of the needles reach the prostatic base, about 1 cc of lidocaine solution is injected in the intraprostatic track, as the needle is slowly withdrawn, for a total volume of 15 cc. The implants are done with a Mick Applicator, inserting and loading groups of two to four needles, so that a maximum of only about four needles are in the patient at any one time. During the implant procedure, an additional 1 cc of lidocaine solution is injected into one or more needle tracks if the patient experiences substantial discomfort. The total dose of lidocaine is generally limited to 500 mg (50 ml of 1% solution). Results: To date, we have implanted approximately 50 patients in our simulator suite, using local anesthesia. Patients' heart rate and diastolic blood pressure usually showed moderate changes, consistent with some discomfort. The time from first subcutaneous injection and completion of the source insertion ranged from 35 to 90 minutes. Serum lidocaine levels were below or at the low range of therapeutic. There has been only one instance of acute urinary retention in the

  14. Dosimetric characterization of interstitial radiotherapy sources: application to iridium 192

    192Ir interstitial radiotherapy sources have been characterized in terms of normal kerma-rate in air ksub(n), with an air-filled graphite cavity chamber of known volume, thus leading to primary standards. The distribution of absorbed dose in water has been studied, at different depths in a phantom, with an intracavitary chamber and with lithium fluoride thermoluminescent dosemeters. These two experimental investigations, complemented with the establishment of a rigorous formalism, made it possible to determine the transmission function phi(d) in water, which is used in calculation codes for interstitial therapy. The values thus obtained are then compared to these previously published

  15. Preparation of 103Pd brachytherapy seeds by electroless plating of 103Pd onto carbon bars

    A method for preparing 103Pd brachytherapy seeds is reported. The key of the method was to deposit 103Pd onto carbon bars by electroless plating so as to prepare source cores. After each carbon bar with 103Pd was sealed in a titanium capsule, the 103Pd seeds were fabricated. This paper provides valuable experiences and data for the preparation of 103Pd brachytherapy seeds

  16. Study of dose calculation on breast brachytherapy using prism TPS

    PRISM is one of non-commercial Treatment Planning System (TPS) and is developed at the University of Washington. In Indonesia, many cancer hospitals use expensive commercial TPS. This study aims to investigate Prism TPS which been applied to the dose distribution of brachytherapy by taking into account the effect of source position and inhomogeneities. The results will be applicable for clinical Treatment Planning System. Dose calculation has been implemented for water phantom and CT scan images of breast cancer using point source and line source. This study used point source and line source and divided into two cases. On the first case, Ir-192 seed source is located at the center of treatment volume. On the second case, the source position is gradually changed. The dose calculation of every case performed on a homogeneous and inhomogeneous phantom with dimension 20 × 20 × 20 cm3. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm3. The results of dose calculations using PRISM TPS were compared to literature data. From the calculation of PRISM TPS, dose rates show good agreement with Plato TPS and other study as published by Ramdhani. No deviations greater than ±4% for all case. Dose calculation in inhomogeneous and homogenous cases show similar result. This results indicate that Prism TPS is good in dose calculation of brachytherapy but not sensitive for inhomogeneities. Thus, the dose calculation parameters developed in this study were found to be applicable for clinical treatment planning of brachytherapy

  17. Study of dose calculation on breast brachytherapy using prism TPS

    Fendriani, Yoza; Haryanto, Freddy

    2015-09-01

    PRISM is one of non-commercial Treatment Planning System (TPS) and is developed at the University of Washington. In Indonesia, many cancer hospitals use expensive commercial TPS. This study aims to investigate Prism TPS which been applied to the dose distribution of brachytherapy by taking into account the effect of source position and inhomogeneities. The results will be applicable for clinical Treatment Planning System. Dose calculation has been implemented for water phantom and CT scan images of breast cancer using point source and line source. This study used point source and line source and divided into two cases. On the first case, Ir-192 seed source is located at the center of treatment volume. On the second case, the source position is gradually changed. The dose calculation of every case performed on a homogeneous and inhomogeneous phantom with dimension 20 × 20 × 20 cm3. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm3. The results of dose calculations using PRISM TPS were compared to literature data. From the calculation of PRISM TPS, dose rates show good agreement with Plato TPS and other study as published by Ramdhani. No deviations greater than ±4% for all case. Dose calculation in inhomogeneous and homogenous cases show similar result. This results indicate that Prism TPS is good in dose calculation of brachytherapy but not sensitive for inhomogeneities. Thus, the dose calculation parameters developed in this study were found to be applicable for clinical treatment planning of brachytherapy.

  18. Predictors of Cosmetic Outcome Following MammoSite Breast Brachytherapy: A Single-Institution Experience of 100 Patients With Two Years of Follow-Up

    Purpose: To identify the factors that predict for excellent cosmesis in patients who receive MammoSite breast brachytherapy (MBT). Methods and Materials: One hundred patients with Stage 0, I, or II adenocarcinoma of the breast underwent adjuvant therapy using MBT. A dose of 34 Gy, delivered in 10 fractions twice daily, was prescribed to 1-cm depth using 192Ir high-dose-rate brachytherapy. Patients were assessed for acute toxicity on the day of therapy completion, 4 weeks after therapy, and at least every 3 months by radiation, surgical, and/or medical oncologists. All available data were reviewed for documentation of cosmesis and rated using the Harvard Scale. All patients had a minimum follow-up of 6 months (median = 24 months). Results: Of 100 patients treated, 90 had adequate data and follow-up. Cosmesis was excellent in 62 (68.9%), good in 19 (21.1%), fair in 8 (8.9%), and poor in 1 (1.1%) patient. Using stepwise logistic regression, the factors that predicted for excellent cosmesis were as follows: the absence vs. presence of infection (p = 0.017), and the absence vs. presence of acute skin toxicity (p = 0.026). There was a statistically significant association between acute skin toxicity (present vs. absent) and balloon-to-skin distance (8 mm, p = 0.001). Factors that did not predict for cosmesis were age, balloon placement technique, balloon volume, catheter days in situ, subcutaneous toxicity, and chemotherapy or hormonal therapy. Conclusions: The acute and late-term toxicity profiles of MBT have been acceptable. Cosmetic outcome is improved by proper patient selection and infection prevention

  19. Erectile function after prostate brachytherapy

    Purpose: To evaluate erectile function after permanent prostate brachytherapy using a validated patient-administered questionnaire and to determine the effect of multiple clinical, treatment, and dosimetric parameters on penile erectile function. Methods and materials: A total of 226 patients with preimplant erectile function determined by the International Index of Erectile Function (IIEF) questionnaire underwent permanent prostate brachytherapy in two prospective randomized trials between February 2001 and January 2003 for clinical Stage T1c-T2c (2002 American Joint Committee on Cancer) prostate cancer. Of the 226 patients, 132 were potent before treatment and, of those, 128 (97%) completed and returned the IIEF questionnaire after brachytherapy. The median follow-up was 29.1 months. Potency was defined as an IIEF score of ≥13. The clinical, treatment, and dosimetric parameters evaluated included patient age; preimplant IIEF score; clinical T stage; pretreatment prostate-specific antigen level; Gleason score; elapsed time after implantation; preimplant nocturnal erections; body mass index; presence of hypertension or diabetes mellitus; tobacco consumption; the volume of the prostate gland receiving 100%, 150%, and 200% of the prescribed dose (V100/150/200); the dose delivered to 90% of the prostate gland (D90); androgen deprivation therapy; supplemental external beam radiotherapy (EBRT); isotope; prostate volume; planning volume; and radiation dose to the proximal penis. Results: The 3-year actuarial rate of potency preservation was 50.5%. For patients who maintained adequate posttreatment erectile function, the preimplant IIEF score was 29, and in patients with brachytherapy-related ED, the preimplant IIEF score was 25. The median time to the onset of ED was 5.4 months. After brachytherapy, the median IIEF score was 20 in potent patients and 3 in impotent patients. On univariate analysis, the preimplant IIEF score, patient age, presence of nocturnal erections

  20. Radiological protection on interstitial brachytherapy and dose determination and exposure rate of an Ir-192 source through the MCNP-4B; Proteccion radiologica en braquiterapia intersticial y determinacion de la dosis y tasa de exposicion de una fuente de Ir-192 mediante el MCNP-4B

    Morales L, M.E. [INEN, Av. Angamos Este 2520- Surquillo, Lima (Peru)

    2006-07-01

    The present work was carried out in the Neurological Sciences Institute having as objective to determine the dose and the rate of exhibition of the sources of Iridium 192, Iodine 125 and Palladium 103; which are used to carry out implant in the Interstitial Brachytherapy according to the TG43. For it we carry out a theoretical calculation, its are defined in the enter file: the geometry, materials of the problem and the radiation source, etc; in the MCNP-4B Monte Carlo code, considering a punctual source and for the dose determination we simulate thermoluminescent dosemeters (TLD): at 5 cm, 50 cm, 100 cm and 200 cm of the source. Our purpose is to analyze the radioprotection measures that should take into account in this Institute in which are carried out brain biopsies using a Micro mar stereotactic mark, and in a near future with the collaboration of a doctor and a cuban physique seeks to be carried out the Interstitial Brachytherapy technique with sources of Ir-192 for patient with tumors like glioblastoma, astrocytoma, etc. (Author)

  1. Experiences with alanine dosimetry in afterloading brachytherapy

    At the present, the most commonly used dosimetry for radiotherapy applications are ionisation chambers and thermoluminescent dosimeters (TLD). However, there are some undesirable characteristics of these dosimetry systems, such as large detection volume (ionisation chamber) as well as fading of the radiation induced signal with time and destructive readout (TLG). The present study is an investigation into the use of the alanine/ESR dosimetry in fractionated afterloading brachytherapy during the whole radiotherapy course. There are some qualities which make alanine dosimetry attractive. These are the linear energy response, low fading under standard conditions, and the nondestructive readout. Thus the alanine dosimetry makes possible cumulative dose measurements during the radiotherapy course and an archival storage. By ionizing radiation (gamma, e, n, p, charged particles) free radicals (unpaired electrons) are produced in the amino acid alanine. The continuous wave electron spin resonance (ESR) spectroscopy is used to determine the number of free radicals, which is proportional to the absorbed dose and the alanine content of the dosimeter. The ESR measurements were made at room temperature using a Bruker EPR analyzer EMS-104. The dosimeters used in the test are alanine pellets (23.72 mg weight, 4.9 mm diameter, 1 mm height) as well as flexible alanine film dosimeters (thickness about 500 μm). The dosimeters consist of a blend of L-alpha-alanine and a binder. The alanine content of the pellets and the film dosimeters is about 88 % and 50 % by weight, respectively. The dosimeters for the calculation of the dose-effect-relationship were irradiated at the Physical-Technical Bundesanstalt in Braunschweig by a standard 60Co source. The maximum deviation from the calculated linear function is about 0.12 Gy in the dose range up to 80 Gy. The goal of medical applications was the superficial dose measurement in afterloading brachytherapy during the radiotherapy course in

  2. SU-E-T-270: Quality Control of Source Strength and Indexer Length in HDR Brachytherapy Using Sun Nuclear Mapcheck2

    Purpose: The goal of this work was to evaluate Sun Nuclear MapCheck2 capability for quantitative determination of both HDR source strength and position. Predictive power of Mapcheck2 dose matrix, originated by a microSelectron-v2 source from 22mm distance, was investigated. Methods: A Mick MultiDoc phantom with the 1400mm indexer length mark aligned over MapCheck2 central detector plus two additional 5cm plastic slabs were used as a composite phantom. Dose readings were transformed by applying published source anisotropy corrections and experimentally established radial dose and relative sensitivity factors. Angular dependence was not considered. Only readings from diodes located 2cm around the central detector were evaluated. The reproducibility of a fit between transformed dose readings and the ratio of virtual source strength and the square of source-detector distance was investigated. Four parameters were considered in the model: virtual source strength, lateral, longitudinal and vertical source positions. Final source strength calibration factor was calculated from the ratio of reference measurements and results from the fit. Results: Original lateral and longitudinal source position estimations had systematic errors of 0.39mm and 0.75mm. After subtracting these errors, both source positions were predicted with a standard deviation of 0.15mm. Results for vertical positions were reproducible with a standard deviation of 0.05mm. The difference between calculated and reference source strengths from 34 independent measurement setups had a standard deviation of 0.3%. The coefficient of determination for the linear regression between known indexer lengths and results from the fit in the range 1400mm ± 5mm was 0.985. Conclusions: ource strength can be estimated with MapCheck2 at appropriate accuracy levels for quality control. Verification of indexer length with present implementation is more accurate than visual alternatives. Results can be improved by designing a

  3. A simple estimate of production of medical isotopes by photo-neutron reaction at the Canadian Light Source

    In contrast to the conventional bremsstrahlung photon beam sources, the laser back scatter photon sources at electron synchrotrons provide the selective tuning capability of photons of energies of interest. This feature coupled with the ubiquitous giant dipole resonance excitations of atomic nuclei promise a fertile ground of nuclear isotope productions. In this article, we present the results of simulations of production of medical/industrial isotopes 196Au, 192Ir and 99Mo by (γ,n) reactions. We employed FLUKA Monte Carlo code along with the simulated photon flux for a beamline at the Canadian Light Source in conjunction with a CO2 laser system. (author)

  4. Salvage brachytherapy for patients with locally persistent nasopharyngeal carcinoma

    Purpose: Locally persistent nasopharyngeal carcinoma (NPC) carries an increased risk of local failure if additional treatment is not given. This study was conducted to evaluate the outcomes of patients with locally persistent NPC as treated by high-dose-rate (HDR) intracavitary brachytherapy, and to explore whether routine brachytherapy boost could improve the local control. Methods and Materials: Eighty-seven patients with locally persistent NPC treated during 1990-1998 with HDR intracavitary brachytherapy were retrospectively analyzed. Fibreoptic nasopharyngoscopy was performed 3-6 weeks after completion of the primary external radiation therapy (ERT). Biopsies were only taken from suspicious areas. Those with complete regression of local disease were put on observation. Eighty-seven patients were shown to have persistent viable disease at a median time of 6 weeks post-RT. The distribution according to Ho's staging system at initial diagnosis was as follows: Stage I-8, II-33, III-41, IV-5; T1-19, T2-48, T3-20; N0-32, N1-22, N2-28, N3-5. CT scan for restaging was not performed after the documentation of persistent disease. Our policy was to treat all patients with persistent disease with brachytherapy irrespective of the extent of disease just prior to brachytherapy. They were treated with HDR intracavitary brachytherapy, with either cobalt sources or an iridium source, giving 22.5-24 Gy in 3 weekly sessions in all but 4 patients. This dose was prescribed at a distance of 1.5 cm from the center of the surface as defined by the sources in the first six patients and subsequently reduced to 1 cm for the others. Twelve patients were treated with neoadjuvant chemotherapy. To compare the efficacy of brachytherapy, another 383 consecutive nonmetastatic patients, treated with curative intent by ERT, during the years 1990-1993, were evaluated. Multivariate analysis was performed using the Cox regression proportional hazards model. Results: The 5-year actuarial local

  5. Evaluation of resins for use in brachytherapy

    Carvalho, Luiz Claudio F.M. Garcia; Ferraz, Wilmar Barbosa; Chrcanovic, Bruno Ramos; Santos, Ana Maria M., E-mail: ferrazw@cdtn.b, E-mail: amms@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    Brachytherapy is an advanced cancer treatment where radioactive seeds or sources are placed near or directly into the tumor thus reducing the radiation exposure in the surrounding healthy tissues. Prostate cancer can be treated with interstitial brachytherapy in initial stage of the disease in which tiny radioactive seeds with cylindrical geometry are used. Several kinds of seeds have been developed in order to obtain a better dose distribution around them and with a lower cost manufacturing. These seeds consist of an encapsulation, a radionuclide carrier, and X-ray marker. Among the materials that have potential for innovation in the construction of seeds, biocompatible resins appear as an important option. In this paper, we present some characterization results with Fourier transform infrared spectroscopic (FTIR) and ultraviolet-visible spectroscopy (UV-vis) performed on two types of resins in which curing temperatures for each one were varied as also the results of coatings with these resins under titanium substrates. Interactions of these resins in contact with the simulated body fluid were evaluated by atomic force microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. (author)

  6. Toxicity and cosmetic result of partial breast high-dose-rate interstitial brachytherapy for conservatively operated early breast cancer

    Objective: Objective To study the method, side effects and cosmetic outcome of high- dose-rate (HDR) accelerated partial breast interstitial irradiation (APBI) alone in early stage breast cancer' after conservative surgery. Methods: From February 2002 to June 2003,47 breast cancer lesions from 46 patients suffering from stage I/II breast cancer were treated with HDR 192Ir APBI after conservative surgery. All patients were over 40 year-old, with T1-2N0-1 (≤3 lymph nodes positive), surgical margin > 1-2 mm, but those having lobular or inflammatory breast cancer were excluded. HDR brachytherapy with 34 Gy, 10 fractions/5 days was used after surgery, toxic reaction and cosmetic outcome were observed in one month, 6 and 12 months respectively. Results: Follow up of 1846 months, 34 months was carried out for the whole group. During the treatment, acute reactions including: erythema, edema, tenderness and infection, all under I-II grade, none of III-IV grade were observed in 21 patients(46%); late toxicity reactions: skin fibrosis, breast tenderness, fat necrosis, and telangiectasia, totally 20 patients (43%) were observed: 2 patients in III grade but one patient received 6 cycle chemotherapy. The result of cosmetic outcome evaluation was excellent or good, at 6 months 95% and 12 months 98%, respectively, but there was no recurfence. Conclusions: Excellent and favorable cosmetic results are noted after APBI by interstitial alone. Acute and late reactions are few. Long term observation is necessary for the rate of' local control. (authors)

  7. Brachytherapy dosimeter with silicon photomultipliers

    Moutinho, L.M., E-mail: moutinho@ua.pt [i3N, Physics Department, University of Aveiro (Portugal); Castro, I.F.C. [i3N, Physics Department, University of Aveiro (Portugal); Peralta, L. [Faculdade de Ciências da Universidade de Lisboa (Portugal); Laboratório de Instrumentação e Física Experimental de Partículas (LIP), Lisboa (Portugal); Abreu, M.C. [Laboratório de Instrumentação e Física Experimental de Partículas (LIP), Lisboa (Portugal); Veloso, J.F.C.A. [i3N, Physics Department, University of Aveiro (Portugal)

    2015-07-01

    In-vivo and in-situ measurement of the radiation dose administered during brachytherapy faces several technical challenges, requiring a very compact, tissue-equivalent, linear and highly sensitive dosimeter, particularly in low-dose rate brachytherapy procedures, which use radioactive seeds with low energy and low dose deposition rate. In this work we present a scintillating optical fiber dosimeter composed of a flexible sensitive probe and a dedicated electronic readout system based on silicon photomultiplier photodetection, capable of operating both in pulse and current modes. The performance of the scintillating fiber optic dosimeter was evaluated in low energy regimes, using an X-ray tube operating at voltages of 40–50 kV and currents below 1 mA, to assess minimum dose response of the scintillating fiber. The dosimeter shows a linear response with dose and is capable of detecting mGy dose variations like an ionization chamber. Besides fulfilling all the requirements for a dosimeter in brachytherapy, the high sensitivity of this device makes it a suitable candidate for application in low-dose rate brachytherapy. According to Peralta and Rego [1], the BCF-10 and BCF-60 scintillating optical fibers used in dosimetry exhibit high variations in their sensitivity for photon beams in the 25–100 kVp energy range. Energy linearity for energies below 50 keV needs to be further investigated, using monochromatic X-ray photons.

  8. Brachytherapy dosimeter with silicon photomultipliers

    Moutinho, L. M.; Castro, I. F. C.; Peralta, L.; Abreu, M. C.; Veloso, J. F. C. A.

    2015-07-01

    In-vivo and in-situ measurement of the radiation dose administered during brachytherapy faces several technical challenges, requiring a very compact, tissue-equivalent, linear and highly sensitive dosimeter, particularly in low-dose rate brachytherapy procedures, which use radioactive seeds with low energy and low dose deposition rate. In this work we present a scintillating optical fiber dosimeter composed of a flexible sensitive probe and a dedicated electronic readout system based on silicon photomultiplier photodetection, capable of operating both in pulse and current modes. The performance of the scintillating fiber optic dosimeter was evaluated in low energy regimes, using an X-ray tube operating at voltages of 40-50 kV and currents below 1 mA, to assess minimum dose response of the scintillating fiber. The dosimeter shows a linear response with dose and is capable of detecting mGy dose variations like an ionization chamber. Besides fulfilling all the requirements for a dosimeter in brachytherapy, the high sensitivity of this device makes it a suitable candidate for application in low-dose rate brachytherapy. According to Peralta and Rego [1], the BCF-10 and BCF-60 scintillating optical fibers used in dosimetry exhibit high variations in their sensitivity for photon beams in the 25-100 kVp energy range. Energy linearity for energies below 50 keV needs to be further investigated, using monochromatic X-ray photons.

  9. In vivo dosimetry in brachytherapy

    Tanderup, Kari; Beddar, Sam; Andersen, Claus Erik; Kertzscher Schwencke, Gustavo Adolfo Vladimir; Cygler, Joanna E.

    2013-01-01

    In vivo dosimetry (IVD) has been used in brachytherapy (BT) for decades with a number of different detectors and measurement technologies. However, IVD in BT has been subject to certain difficulties and complexities, in particular due to challenges of the high-gradient BT dose distribution and the...

  10. Brachytherapy in coronary artery disease

    Song, Ho Chun [Chonnam National University Medicine School, Gwangju (Korea, Republic of)

    2006-04-15

    Coronary artery disease is a leading cause of morbidity and mortality across the world. Percutaneous coronary intervention has become the major technique of revascularization. However, restenosis remains a major limitation of this procedure. Recently the need for repeat intervention due to restenosis, the most vexing long-term failure of percutaneous coronary intervention, has been significantly reduced owing to the introduction to two major advances, intracoronary brachytherapy and the drug-eluting stents, intracoronary brachytherapy has been employed in recent years to prevent restenosis lesions with effective results, principally in in-stent restenosis. Restenosis is generally considered as an excessive form of normal wound healing divided up in processes: elastic recoil, neointimal hyperplasia, and negative vascular remodeling. Restenosis has previously been regarded as a proliferative process in which neointimal thickening, mediated by a cascade of inflammatory mediators and other factors, is the key factor. Ionizing radiation has been shown to decrease the proliferative response to injury in animal models of restenosis. Subsequently, several randomized, double-blind trials have demonstrated that intracoronary brachytherapy can reduce the rates to both angiographic restenosis and clinical event rates in patients undergoing percutaneous coronary intervention for in-stent restenosis.