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Sample records for brachytherapy dose calculation

  1. Dose calculation in brachytherapy with microcomputers

    International Nuclear Information System (INIS)

    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.)

  2. Evolution of dose distribution calculations in brachytherapy

    International Nuclear Information System (INIS)

    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

  3. Study of dose calculation on breast brachytherapy using prism TPS

    International Nuclear Information System (INIS)

    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

  4. Study of dose calculation on breast brachytherapy using prism TPS

    Science.gov (United States)

    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.

  5. Study of dose calculation on breast brachytherapy using prism TPS

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    Fendriani, Yoza; Haryanto, Freddy [Nuclear Physics and Biophysics Research Division, FMIPA Institut Teknologi Bandung, Physics Buildings, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    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 cm{sup 3}. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm{sup 3}. 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.

  6. Comparison of dose calculation methods for brachytherapy of intraocular tumors

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    Rivard, Mark J.; Chiu-Tsao, Sou-Tung; Finger, Paul T.; Meigooni, Ali S.; Melhus, Christopher S.; Mourtada, Firas; Napolitano, Mary E.; Rogers, D. W. O.; Thomson, Rowan M.; Nath, Ravinder [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Quality MediPhys LLC, Denville, New Jersey 07834 (United States); New York Eye Cancer Center, New York, New York 10065 (United States); Department of Radiation Oncology, Comprehensive Cancer Center of Nevada, Las Vegas, Nevada 89169 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Radiation Physics, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030 (United States) and Department of Experimental Diagnostic Imaging, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Physics, Elekta Inc., Norcross, Georgia 30092 (United States); Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520 (United States)

    2011-01-15

    Purpose: To investigate dosimetric differences among several clinical treatment planning systems (TPS) and Monte Carlo (MC) codes for brachytherapy of intraocular tumors using {sup 125}I or {sup 103}Pd plaques, and to evaluate the impact on the prescription dose of the adoption of MC codes and certain versions of a TPS (Plaque Simulator with optional modules). Methods: Three clinical brachytherapy TPS capable of intraocular brachytherapy treatment planning and two MC codes were compared. The TPS investigated were Pinnacle v8.0dp1, BrachyVision v8.1, and Plaque Simulator v5.3.9, all of which use the AAPM TG-43 formalism in water. The Plaque Simulator software can also handle some correction factors from MC simulations. The MC codes used are MCNP5 v1.40 and BrachyDose/EGSnrc. Using these TPS and MC codes, three types of calculations were performed: homogeneous medium with point sources (for the TPS only, using the 1D TG-43 dose calculation formalism); homogeneous medium with line sources (TPS with 2D TG-43 dose calculation formalism and MC codes); and plaque heterogeneity-corrected line sources (Plaque Simulator with modified 2D TG-43 dose calculation formalism and MC codes). Comparisons were made of doses calculated at points-of-interest on the plaque central-axis and at off-axis points of clinical interest within a standardized model of the right eye. Results: For the homogeneous water medium case, agreement was within {approx}2% for the point- and line-source models when comparing between TPS and between TPS and MC codes, respectively. For the heterogeneous medium case, dose differences (as calculated using the MC codes and Plaque Simulator) differ by up to 37% on the central-axis in comparison to the homogeneous water calculations. A prescription dose of 85 Gy at 5 mm depth based on calculations in a homogeneous medium delivers 76 Gy and 67 Gy for specific {sup 125}I and {sup 103}Pd sources, respectively, when accounting for COMS-plaque heterogeneities. For off

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    Brachytherapy treatments have been performed based on TG-43U1 water dose formalism which neglects human tissues density and composition, body interfaces and applicator effects. As these effects could be relevant for brachytherapy energy range, modern treatment planning systems (TPS) are now available that are based on model-based dose calculation algorithms (MBDCA) enabling heterogeneity corrections, which are needed to replace the TG-43U1 water dose formalism for a more accurate approach. The recently published AAPM TG-186 report is the first step towards to a TPS taking into account heterogeneities, applicators and human body complexities. This report presents the current status, recommendations for clinical implementation and specifies research areas where considerable efforts are necessary to move forward with MBDCA. Monte Carlo (MC) codes are an important part of the current algorithms due their flexibility and accuracy, although, almost all MC codes present no interface to process the large amount of data necessary to perform clinical cases simulations, which may include hundreds of dwell positions, inter-seed attenuation, image processing and others time consuming issues that can make MC simulation unfeasible without a pre-processing interface. This work presents the AMIGOBrachy interface tool (Algorithm for Medical Image-based Generating Object - Brachytherapy module) which provides all the pre-processing task needed for the simulation. This software can import and edit treatments plans from BrachyVision™ (Varian Medical Systems, Inc., Palo Alto, CA) and ONCENTRA™ (Elekta AB, Stockholm, Sweden), and also create a new plan through contouring resources, needle recognition, HU segmentation, combining voxels phantoms with analytical geometries to define applicators and other resources used to create MCNP5 input and analyze the results. This work presents some results used to validate the software and to evaluate the heterogeneities impact in a clinical case

  10. Deterministic calculations of radiation doses from brachytherapy seeds

    International Nuclear Information System (INIS)

    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)

  11. Calculations radiobiological using the quadratic lineal model in the use of the medium dose rate absorbed in brachytherapy. Pt. 3

    International Nuclear Information System (INIS)

    Calculations with the quadratic lineal model for medium rate using the equation dose-effect. Several calculations for system of low dose rate brachytherapy plus teletherapy, calculations for brachytherapy with medium dose rate together with teletherapy, dose for fraction and the one numbers of fractions in medium rate

  12. Monte-Carlo Method Python Library for dose distribution Calculation in Brachytherapy

    International Nuclear Information System (INIS)

    The Cs-137 Brachytherapy treatment is performed in Madagascar since 2005. Time treatment calculation for prescribed dose is made manually. Monte-Carlo Method Python library written at Madagascar INSTN is experimentally used to calculate the dose distribution on the tumour and around it. The first validation of the code was done by comparing the library curves with the Nucletron company curves. To reduce the duration of the calculation, a Grid of PC's is set up with listner patch run on each PC. The library will be used to modelize the dose distribution in the CT scan patient picture for individual and better accuracy time calculation for a prescribed dose.

  13. Comparison between calculation methods of dose rates in gynecologic brachytherapy

    International Nuclear Information System (INIS)

    In treatments with radiations for gynecologic tumors is necessary to evaluate the quality of the results obtained by different calculation methods for the dose rates on the points of clinical interest (A, rectal, vesicle). The present work compares the results obtained by two methods. The Manual Calibration Method (MCM) tri dimensional (Vianello E., et.al. 1998), using orthogonal radiographs for each patient in treatment, and the Theraplan/T P-11 planning system (Thratonics International Limited 1990) this last one verified experimentally (Vianello et.al. 1996). The results show that MCM can be used in the physical-clinical practice with a percentile difference comparable at the computerized programs. (Author)

  14. Suitability of point kernel dose calculation techniques in brachytherapy treatment planning

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    Lakshminarayanan Thilagam

    2010-01-01

    Full Text Available Brachytherapy treatment planning system (TPS is necessary to estimate the dose to target volume and organ at risk (OAR. TPS is always recommended to account for the effect of tissue, applicator and shielding material heterogeneities exist in applicators. However, most brachytherapy TPS software packages estimate the absorbed dose at a point, taking care of only the contributions of individual sources and the source distribution, neglecting the dose perturbations arising from the applicator design and construction. There are some degrees of uncertainties in dose rate estimations under realistic clinical conditions. In this regard, an attempt is made to explore the suitability of point kernels for brachytherapy dose rate calculations and develop new interactive brachytherapy package, named as BrachyTPS, to suit the clinical conditions. BrachyTPS is an interactive point kernel code package developed to perform independent dose rate calculations by taking into account the effect of these heterogeneities, using two regions build up factors, proposed by Kalos. The primary aim of this study is to validate the developed point kernel code package integrated with treatment planning computational systems against the Monte Carlo (MC results. In the present work, three brachytherapy applicators commonly used in the treatment of uterine cervical carcinoma, namely (i Board of Radiation Isotope and Technology (BRIT low dose rate (LDR applicator and (ii Fletcher Green type LDR applicator (iii Fletcher Williamson high dose rate (HDR applicator, are studied to test the accuracy of the software. Dose rates computed using the developed code are compared with the relevant results of the MC simulations. Further, attempts are also made to study the dose rate distribution around the commercially available shielded vaginal applicator set (Nucletron. The percentage deviations of BrachyTPS computed dose rate values from the MC results are observed to be within plus/minus 5

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

    International Nuclear Information System (INIS)

    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

  16. Dose calculations of brachytherapy with compensations of gamma-ray absorption

    International Nuclear Information System (INIS)

    A dose-distribution calculation system for the brachytherapy was developed with a personal-computer (NEC PC-9800 series). The operating system, MS-DOS ver. 2.1, was used and the programs were written by the compiler BASIC and the assembler. The followings are the features of the system. The system can be realized with low cost compared to a commercially available mini-computer system. And the system has high performances in the speed of calculation and data-transfer without the lack of accuracy. Moreover the gamma rays absorption within sources and their containers are considered in the calculation of the table-data. (author)

  17. Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition

    International Nuclear Information System (INIS)

    Purpose: The objective of this work is to assess the sensitivity of Monte Carlo (MC) dose calculations to uncertainties in human tissue composition for a range of low photon energy brachytherapy sources: 125I, 103Pd, 131Cs, and an electronic brachytherapy source (EBS). The low energy photons emitted by these sources make the dosimetry sensitive to variations in tissue atomic number due to the dominance of the photoelectric effect. This work reports dose to a small mass of water in medium Dw,m as opposed to dose to a small mass of medium in medium Dm,m. Methods: Mean adipose, mammary gland, and breast tissues (as uniform mixture of the aforementioned tissues) are investigated as well as compositions corresponding to one standard deviation from the mean. Prostate mean compositions from three different literature sources are also investigated. Three sets of MC simulations are performed with the GEANT4 code: (1) Dose calculations for idealized TG-43-like spherical geometries using point sources. Radial dose profiles obtained in different media are compared to assess the influence of compositional uncertainties. (2) Dose calculations for four clinical prostate LDR brachytherapy permanent seed implants using 125I seeds (Model 2301, Best Medical, Springfield, VA). The effect of varying the prostate composition in the planning target volume (PTV) is investigated by comparing PTV D90 values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using 103Pd seeds (Model 2335, Best Medical). The effects of varying the adipose/gland ratio in the PTV and of varying the elemental composition of adipose and gland within one standard deviation of the assumed mean composition are investigated by comparing PTV D90 values. For (2) and (3), the influence of using the mass density from CT scans instead of unit mass density is also assessed. Results: Results from simulation (1) show that variations in the mean compositions of tissues affect low energy

  18. Brachytherapy scatter dose calculation in heterogeneous media: II. Empirical formulation for the multiple-scatter contribution

    International Nuclear Information System (INIS)

    The presence of heterogeneous media can produce significant perturbations of dose distribution in brachytherapy. In a companion paper, we proposed a dose decomposition approach for dose calculation in a heterogeneous medium, which separately treats dose contributions from primary, once-scattered and multiple-scattered photons. The companion paper also describes and verifies a micro-beam ray-tracing method for evaluating the once-scatter dose. This paper deals with the calculation of the multiple-scatter dose. We present two empirical formulations for evaluating the heterogeneity correction factor for a 27 keV point source in a water sphere containing a disc-shaped heterogeneity. The empirical formulations are based on nonlinear curve fitting of the Monte Carlo multiple-scatter dose estimates calculated for the heterogeneous system. Extensive benchmark comparisons show that these formulations provide results for the multiple-scatter dose that agree within 10% (and mostly within 5%) with corresponding Monte Carlo dose estimates. Combining them with the algorithms for primary and once-scatter dose calculation described in the companion paper yields results for the total dose of equivalent accuracy. The empirical formulations are expressed in simple mathematical forms which involve a separation of the geometry and position variables of the heterogeneous system. Such representation provides a good tool to investigate the heterogeneity-induced perturbation of a multiple-scatter dose at low photon energy

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

    Science.gov (United States)

    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

  20. Development of dose calculation system of brachytherapy with a personal computer. 138

    International Nuclear Information System (INIS)

    A dose calculation system for the brachytherapy was developed with a personal computer. The system was made up of a 16 bits personal computer and a digitizer with a light panel. As the operating system, MS-DOS version 2.1 was used and the programs were written in the BASIC (compiler version) and the assembler. The followings are characteristics of the systeM1; (1) low cost, (2) high performances in the speed of calculation and the data-transfer, (3) high accuracy of the calculated dose-distribution, (4) consideration of the absorption of gamma rays within sources themselves and their containers. In this paper, functions of the system and the performances are described minutely. Moreover, we show the results of estimation of the accuracy of the calculated dose. 10 refs.; 5 figs.; 1 table

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

    International Nuclear Information System (INIS)

    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)

  2. An image-guidance system for dynamic dose calculation in prostate brachytherapy using ultrasound and fluoroscopy

    International Nuclear Information System (INIS)

    Purpose: Brachytherapy is a standard option of care for prostate cancer patients but may be improved by dynamic dose calculation based on localized seed positions. The American Brachytherapy Society states that the major current limitation of intraoperative treatment planning is the inability to localize the seeds in relation to the prostate. An image-guidance system was therefore developed to localize seeds for dynamic dose calculation. Methods: The proposed system is based on transrectal ultrasound (TRUS) and mobile C-arm fluoroscopy, while using a simple fiducial with seed-like markers to compute pose from the nonencoded C-arm. Three or more fluoroscopic images and an ultrasound volume are acquired and processed by a pipeline of algorithms: (1) seed segmentation, (2) fiducial detection with pose estimation, (3) seed matching with reconstruction, and (4) fluoroscopy-to-TRUS registration. Results: The system was evaluated on ten phantom cases, resulting in an overall mean error of 1.3 mm. The system was also tested on 37 patients and each algorithm was evaluated. Seed segmentation resulted in a 1% false negative rate and 2% false positive rate. Fiducial detection with pose estimation resulted in a 98% detection rate. Seed matching with reconstruction had a mean error of 0.4 mm. Fluoroscopy-to-TRUS registration had a mean error of 1.3 mm. Moreover, a comparison of dose calculations between the authors’ intraoperative method and an independent postoperative method shows a small difference of 7% and 2% forD90 and V100, respectively. Finally, the system demonstrated the ability to detect cold spots and required a total processing time of approximately 1 min. Conclusions: The proposed image-guidance system is the first practical approach to dynamic dose calculation, outperforming earlier solutions in terms of robustness, ease of use, and functional completeness

  3. SU-E-T-397: Include Organ Deformation Into Dose Calculation of Prostate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: Prostate brachytherapy is an important curative treatment for patients with localized prostate cancer. In brachytherapy, rectal balloon is generally needed to adjust for unfavorable prostate position for seed placement. However, rectal balloon causes prostate deformation, which is not accounted for in dosimetric planning. Therefore, it is possible that brachytherapy dosimetry deviates significantly from initial plan when prostate returns to its non-deformed state (after procedure). The goal of this study is to develop a method to include prostate deformation into the treatment planning of brachytherapy dosimetry. Methods: We prospectively collected ultrasound images of prostate pre- and post- rectal balloon inflation from thirty five consecutive patients undergoing I-125 brachytherapy. Based on the cylinder coordinate systems, we learned the initial coordinate transformation parameters between the manual segmentations of both deformed and non-deformed prostates of each patient in training set. With the nearest-neighbor interpolation, we searched the best transformation between two coordinate systems to maximum the mutual information of deformed and non-deformed images. We then mapped the implanted seeds of five selected patients from the deformed prostate into non-deformed prostate. The seed position is marked on original pre-inflation US image and it is imported into VariSeed software for dose calculation. Results: The accuracy of image registration is 87.5% as quantified by Dice Index. The prostate coverage V100% dropped from 96.5±0.5% of prostate deformed plan to 91.9±2.6% (p<0.05) of non-deformed plan. The rectum V100% decreased from 0.44±0.26 cc to 0.10±0.18 cc (p<0.05). The dosimetry of the urethra showed mild change but not significant: V150% changed from 0.05±0.10 cc to 0.14±0.15 cc (p>0.05) and D1% changed from 212.9±37.3 Gy to 248.4±42.8 Gy (p>0.05). Conclusion: We have developed a deformable image registration method that allows

  4. Patient-specific Monte Carlo dose calculations for 103Pd breast brachytherapy

    Science.gov (United States)

    Miksys, N.; Cygler, J. E.; Caudrelier, J. M.; Thomson, R. M.

    2016-04-01

    This work retrospectively investigates patient-specific Monte Carlo (MC) dose calculations for 103Pd permanent implant breast brachytherapy, exploring various necessary assumptions for deriving virtual patient models: post-implant CT image metallic artifact reduction (MAR), tissue assignment schemes (TAS), and elemental tissue compositions. Three MAR methods (thresholding, 3D median filter, virtual sinogram) are applied to CT images; resulting images are compared to each other and to uncorrected images. Virtual patient models are then derived by application of different TAS ranging from TG-186 basic recommendations (mixed adipose and gland tissue at uniform literature-derived density) to detailed schemes (segmented adipose and gland with CT-derived densities). For detailed schemes, alternate mass density segmentation thresholds between adipose and gland are considered. Several literature-derived elemental compositions for adipose, gland and skin are compared. MC models derived from uncorrected CT images can yield large errors in dose calculations especially when used with detailed TAS. Differences in MAR method result in large differences in local doses when variations in CT number cause differences in tissue assignment. Between different MAR models (same TAS), PTV {{D}90} and skin {{D}1~\\text{c{{\\text{m}}3}}} each vary by up to 6%. Basic TAS (mixed adipose/gland tissue) generally yield higher dose metrics than detailed segmented schemes: PTV {{D}90} and skin {{D}1~\\text{c{{\\text{m}}3}}} are higher by up to 13% and 9% respectively. Employing alternate adipose, gland and skin elemental compositions can cause variations in PTV {{D}90} of up to 11% and skin {{D}1~\\text{c{{\\text{m}}3}}} of up to 30%. Overall, AAPM TG-43 overestimates dose to the PTV ({{D}90} on average 10% and up to 27%) and underestimates dose to the skin ({{D}1~\\text{c{{\\text{m}}3}}} on average 29% and up to 48%) compared to the various MC models derived using the post-MAR CT images studied

  5. Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom

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    Lesperance, Marielle; Inglis-Whalen, M.; Thomson, R. M., E-mail: rthomson@physics.carleton.ca [Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa K1S 5B6 (Canada)

    2014-02-15

    Purpose : To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with{sup 125}I, {sup 103}Pd, or {sup 131}Cs seeds, and to investigate doses to ocular structures. Methods : An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Results : Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20–30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%–10% and 13%–14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%–17% and 29%–34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model

  6. Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom

    International Nuclear Information System (INIS)

    Purpose : To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with125I, 103Pd, or 131Cs seeds, and to investigate doses to ocular structures. Methods : An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Results : Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20–30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%–10% and 13%–14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%–17% and 29%–34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model simulation by up to 16

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  8. Comparison of methods for calculating rectal dose after 125I prostate brachytherapy implants

    International Nuclear Information System (INIS)

    Purpose: To compare several different methods of calculating the rectal dose and examine how accurately they represent rectal dose surface area measurements and, also, their practicality for routine use. Methods and Materials: This study comprised 55 patients, randomly selected from 295 prostate brachytherapy patients implanted at the Vancouver Cancer Center between 1998 and 2000. All implants used a nonuniform loading of 0.33 mCi (NIST-99) 125I seeds and a prescribed dose of 144 Gy. Pelvic CT scans were obtained for each patient ∼30 days after implantation. For the purposes of calculating the rectal dose, several structures were contoured on the CT images: (1) a 1-mm-thick anterior rectal wall, (2) the anterior half rectum, and (3) the whole rectum. Point doses were also obtained along the anterior rectal surface. The thin wall contour provided a surrogate for a dose-surface histogram (DSH) and was our reference standard rectal dose measurement. Alternate rectal dose measurements (volume, surface area, and length of rectum receiving a dose of interest [DOI] of ≥144 Gy and 216 Gy, as well as point dose measures) were calculated using several methods (VariSeed software) and compared with the surrogate DSH measure (SADOI). Results: The best correlation with SA144Gy was the dose volumes (whole or anterior half rectum) (R = 0.949). The length of rectum receiving ≥144 Gy also correlated well with SA144Gy (R ≥0.898). Point dose measures, such as the average and maximal anterior dose, correlated poorly with SA144Gy (R ≤0.649). The 216-Gy measurements supported these results. In addition, dose-volume measurements were the most practical (∼6 min/patient), with our surrogate DSH the least practical (∼20 min/patient). Conclusion: Dose-volume measurements for the whole or anterior half rectum, because they were the most practical measures and best represented the DSH measurements, should be considered a standard method of reporting the rectal dose when

  9. Calculation of mean central dose in interstitial brachytherapy using Delaunay triangulation

    International Nuclear Information System (INIS)

    In 1997 the ICRU published Report 58 'Dose and Volume Specification for Reporting Interstitial Therapy' with the objective of addressing the problem of absorbed dose specification for reporting contemporary interstitial therapy. One of the concepts proposed in that report is 'mean central dose'. The fundamental goal of the mean central dose (MCD) calculation is to obtain a single, readily reportable and intercomparable value which is representative of dose in regions of the implant 'where the dose gradient approximates a plateau'. Delaunay triangulation (DT) is a method used in computational geometry to partition the space enclosed by the convex hull of a set of distinct points P into a set of nonoverlapping cells. In the three-dimensional case, each point of P becomes a vertex of a tetrahedron and the result of the DT is a set of tetrahedra. All treatment planning for interstitial brachytherapy inherently requires that the location of the radioactive sources, or dwell positions in the case of HDR, be known or digitized. These source locations may be regarded as a set of points representing the implanted volume. Delaunay triangulation of the source locations creates a set of tetrahedra without manual intervention. The geometric centers of these tetrahedra define a new set of points which lie 'in between' the radioactive sources and which are distributed uniformly over the volume of the implant. The arithmetic mean of the dose at these centers is a three dimensional analog of the two-dimensional triangulation and inspection methods proposed for calculating MCD in ICRU 58. We demonstrate that DT can be successfully incorporated into a computerized treatment planning system and used to calculate the MCD

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

    International Nuclear Information System (INIS)

    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)

  11. Development of a program for calculation of second dose and securities in brachytherapy high dose rate

    International Nuclear Information System (INIS)

    We assessed the reliability of the program with 80 patients in the usual points of prescription of each pathology. The average error of the calculation points is less than 0.3% in 95% of cases, finding the major differences in the axes of the applicators (maximum error -0.798%). The program has proved effective previously testing him with erroneous dosimetry. Thanks to the implementation of this program is achieved by the calculation of the dose and part of the process of quality assurance program in a few minutes, highlighting the case of HDR prostate due to having a limited time. Having separate data sheet allows each institution to its protocols modify parameters. (Author)

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

    International Nuclear Information System (INIS)

    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)

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  15. An independent dose-to-point calculation program for the verification of high-dose-rate brachytherapy treatment planning

    International Nuclear Information System (INIS)

    Purpose: We describe computer software that performs, quickly and accurately, secondary dose calculations for high-dose-rate (HDR) treatment plans, including those employed for prostate treatments. Methods: The program takes as primary input the data file used by the HDR remote afterloader console for treatment. Dosimetric calculations are performed using the Meisberger polynomial and the anisotropy table for the HDR Iridium-192 source. For standard applicators, treatment geometry is automatically reconstructed and the dose is calculated at relevant reference point(s). Template-based treatment plans (e.g., prostate) require additional user input; the dose calculation is then performed at user-selected reference points. A total dwell time calculation for volume and planar implants using the Manchester tables was also implemented. Results: For fixed-geometry HDR procedures, secondary dose calculations are within 2% of the treatment plan, and results are available for review instantly. For more general applications, the calculated and planned doses are typically within 3% at the prescription isodose line. The Manchester-based dwell time calculation is within 10% of the planned time

  16. SU-F-19A-01: APBI Brachytherapy Treatment Planning: The Impact of Heterogeneous Dose Calculations

    International Nuclear Information System (INIS)

    Purpose: To quantify the difference in dose to PTV-EVAL and OARs (skin and rib) as calculated by (TG43) and heterogeneous calculations (CCC). Methods: 25 patient plans (5 Contura and 20 SAVI) were selected for analysis. Clinical dose distributions were computed with a commercially available treatment planning algorithm (TG43-D-(w,w)) and then recomputed with a pre-clinical collapsed cone convolution algorithm (CCCD-( m,m)). PTV-EVAL coverage (V90%, V95%), and rib and skin maximum dose were compared via percent difference. Differences in dose to normal tissue (V150cc, V200cc of PTV-EVAL) were also compared. Changes in coverage and maximum dose to organs at risk are reported in percent change, (100*(TG43 − CCC) / TG43)), and changes in maximum dose to normal tissue are absolute change in cc (TG43 − CCC). Results: Mean differences in V90, V95, V150, and V200 for the SAVI cases were −0.2%, −0.4%, −0.03cc, and −0.14cc, respectively, with maximum differences of −0.78%, −1.7%, 1.28cc, and 1.01cc, respectively. Mean differences in the 0.1cc dose to the rib and skin were −1.4% and −0.22%, respectively, with maximum differences of −4.5% and 16%, respectively. Mean differences in V90, V95, V150, and V200 for the Contura cases were −1.2%, −2.1%, −1.8cc, and −0.59cc, respectively, with maximum differences of −2.0%, −3.16%, −2.9cc, and −0.76cc, respectively. Mean differences in the 0.1cc dose to the rib and skin were −2.6% and −3.9%, respectively, with maximum differences of −3.2% and −5.7%, respectively. Conclusion: The effects of translating clinical knowledge based on D-(w,w) to plans reported in D-(m,m) are minimal (2% or less) on average, but vary based on the type and placement of the device, source, and heterogeneity information

  17. SU-E-T-634: Analysis of Volume Based GYN HDR Brachytherapy Plans for Dose Calculation to Organs At Risk(OAR)

    International Nuclear Information System (INIS)

    Purpose: We have analyzed the dose volume histogram of 140 CT based HDR brachytherapy plans and evaluated the dose received to OAR ; rectum, bladder and sigmoid colon based on recommendations from ICRU and Image guided brachytherapy working group for cervical cancer . Methods: Our treatment protocol consist of XRT to whole pelvis with 45 Gy at 1.8Gy/fraction followed by 30 Gy at 6 Gy per fraction by HDR brachytherapy in 2 weeks . The CT compatible tandem and ovoid applicators were used and stabilized with radio opaque packing material. The patient was stabilized using special re-locatable implant table and stirrups for reproducibility of the geometry during treatment. The CT scan images were taken at 3mm slice thickness and exported to the treatment planning computer. The OAR structures, bladder, rectum and sigmoid colon were outlined on the images along with the applicators. The prescription dose was targeted to A left and A right as defined in Manchester system and optimized on geometry . The dosimetry was compared on all plans using the parameter Ci.sec.cGy-1 . Using the Dose Volume Histogram (DVH) obtained from the plans the doses to rectum, sigmoid colon and bladder for ICRU defined points and 2cc volume were analyzed and reported. The following criteria were used for limiting the tolerance dose by volume (D2cc) were calculated. The rectum and sigmoid colon doses were limited to <75Gy. The bladder dose was limited to < 90Gy from both XRT and HDR brachytherapy. Results: The average total (XRT+HDRBT) BED values to prescription volume was 120 Gy. Dose 2cc to rectum was 70Gy +/− 17Gy, dose to 2cc bladder was 82+/−32 Gy. The average Ci.sec.cGy-1 calculated for the HDR plans was 6.99 +/− 0.5 Conclusion: The image based treatment planning enabled to evaluati volume based dose to critical structures for clinical interpretation

  18. SU-E-T-634: Analysis of Volume Based GYN HDR Brachytherapy Plans for Dose Calculation to Organs At Risk(OAR)

    Energy Technology Data Exchange (ETDEWEB)

    Nair, M; Li, C; White, M; Davis, J [Joe Arrington Cancer Center, Lubbock, TX (United States)

    2014-06-15

    Purpose: We have analyzed the dose volume histogram of 140 CT based HDR brachytherapy plans and evaluated the dose received to OAR ; rectum, bladder and sigmoid colon based on recommendations from ICRU and Image guided brachytherapy working group for cervical cancer . Methods: Our treatment protocol consist of XRT to whole pelvis with 45 Gy at 1.8Gy/fraction followed by 30 Gy at 6 Gy per fraction by HDR brachytherapy in 2 weeks . The CT compatible tandem and ovoid applicators were used and stabilized with radio opaque packing material. The patient was stabilized using special re-locatable implant table and stirrups for reproducibility of the geometry during treatment. The CT scan images were taken at 3mm slice thickness and exported to the treatment planning computer. The OAR structures, bladder, rectum and sigmoid colon were outlined on the images along with the applicators. The prescription dose was targeted to A left and A right as defined in Manchester system and optimized on geometry . The dosimetry was compared on all plans using the parameter Ci.sec.cGy-1 . Using the Dose Volume Histogram (DVH) obtained from the plans the doses to rectum, sigmoid colon and bladder for ICRU defined points and 2cc volume were analyzed and reported. The following criteria were used for limiting the tolerance dose by volume (D2cc) were calculated. The rectum and sigmoid colon doses were limited to <75Gy. The bladder dose was limited to < 90Gy from both XRT and HDR brachytherapy. Results: The average total (XRT+HDRBT) BED values to prescription volume was 120 Gy. Dose 2cc to rectum was 70Gy +/− 17Gy, dose to 2cc bladder was 82+/−32 Gy. The average Ci.sec.cGy-1 calculated for the HDR plans was 6.99 +/− 0.5 Conclusion: The image based treatment planning enabled to evaluati volume based dose to critical structures for clinical interpretation.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. Dosimetry in high dose rate endoluminal brachytherapy

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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. Verification of the calculation program for brachytherapy planning system of high dose rate (PLATO); Programa de verificacion del calculo para un sistema de planificacion de braquiterapia de alta tasa de dosis (PLATO)

    Energy Technology Data Exchange (ETDEWEB)

    Almansa, J.; Alaman, C.; Perez-Alija, J.; Herrero, C.; Real, R. del; Ososrio, J. L.

    2011-07-01

    In our treatments are performed brachytherapy high dose rate since 2007. The procedures performed include gynecological intracavitary treatment and interstitial. The treatments are performed with a source of Ir-192 activity between 5 and 10 Ci such that small variations in treatment times can cause damage to the patient. In addition the Royal Decree 1566/1998 on Quality Criteria in radiotherapy establishes the need to verify the monitor units or treatment time in radiotherapy and brachytherapy. All this justifies the existence of a redundant system for brachytherapy dose calculation that can reveal any abnormality is present.

  4. Simulation study on potential accuracy gains from dual energy CT tissue segmentation for low-energy brachytherapy Monte Carlo dose calculations

    Science.gov (United States)

    Landry, Guillaume; Granton, Patrick V.; Reniers, Brigitte; Öllers, Michel C.; Beaulieu, Luc; Wildberger, Joachim E.; Verhaegen, Frank

    2011-10-01

    This work compares Monte Carlo (MC) dose calculations for 125I and 103Pd low-dose rate (LDR) brachytherapy sources performed in virtual phantoms containing a series of human soft tissues of interest for brachytherapy. The geometries are segmented (tissue type and density assignment) based on simulated single energy computed tomography (SECT) and dual energy (DECT) images, as well as the all-water TG-43 approach. Accuracy is evaluated by comparison to a reference MC dose calculation performed in the same phantoms, where each voxel's material properties are assigned with exactly known values. The objective is to assess potential dose calculation accuracy gains from DECT. A CT imaging simulation package, ImaSim, is used to generate CT images of calibration and dose calculation phantoms at 80, 120, and 140 kVp. From the high and low energy images electron density ρe and atomic number Z are obtained using a DECT algorithm. Following a correction derived from scans of the calibration phantom, accuracy on Z and ρe of ±1% is obtained for all soft tissues with atomic number Z in [6,8] except lung. GEANT4 MC dose calculations based on DECT segmentation agreed with the reference within ±4% for 103Pd, the most sensitive source to tissue misassignments. SECT segmentation with three tissue bins as well as the TG-43 approach showed inferior accuracy with errors of up to 20%. Using seven tissue bins in our SECT segmentation brought errors within ±10% for 103Pd. In general 125I dose calculations showed higher accuracy than 103Pd. Simulated image noise was found to decrease DECT accuracy by 3-4%. Our findings suggest that DECT-based segmentation yields improved accuracy when compared to SECT segmentation with seven tissue bins in LDR brachytherapy dose calculation for the specific case of our non-anthropomorphic phantom. The validity of our conclusions for clinical geometry as well as the importance of image noise in the tissue segmentation procedure deserves further

  5. Dose calculation in eye brachytherapy with Ir-192 threads using the Sievert integral and corrected by attenuation and scattering with the Meisberg polynomials

    International Nuclear Information System (INIS)

    The ocular brachytherapy many times unique alternative to conserve the visual organ in patients of ocular cancer, one comes carrying out in the National Institute of Neoplastic Illnesses (INEN) using threads of Iridium 192; those which, they are placed in radial form on the interior surface of a spherical cap of gold of 18 K; the cap remains in the eye until reaching the prescribed dose by the doctor. The main objective of this work is to be able to calculate in a correct and practical way the one time that the treatment of ocular brachytherapy should last to reach the dose prescribed by the doctor. To reach this objective I use the Sievert integral corrected by attenuation effects and scattering (Meisberg polynomials); calculating it by the Simpson method. In the calculations by means of the Sievert integral doesn't take into account the scattering produced by the gold cap neither the variation of the constant of frequency of exposure with the distance. The calculations by means of Sievert integral are compared with those obtained using the Monte Carlo Penelope simulation code, where it is observed that they agree at distances of the surface of the cap greater or equal to 2mm. (Author)

  6. Development of virtual patient models for permanent implant brachytherapy Monte Carlo dose calculations: interdependence of CT image artifact mitigation and tissue assignment

    Science.gov (United States)

    Miksys, N.; Xu, C.; Beaulieu, L.; Thomson, R. M.

    2015-08-01

    This work investigates and compares CT image metallic artifact reduction (MAR) methods and tissue assignment schemes (TAS) for the development of virtual patient models for permanent implant brachytherapy Monte Carlo (MC) dose calculations. Four MAR techniques are investigated to mitigate seed artifacts from post-implant CT images of a homogeneous phantom and eight prostate patients: a raw sinogram approach using the original CT scanner data and three methods (simple threshold replacement (STR), 3D median filter, and virtual sinogram) requiring only the reconstructed CT image. Virtual patient models are developed using six TAS ranging from the AAPM-ESTRO-ABG TG-186 basic approach of assigning uniform density tissues (resulting in a model not dependent on MAR) to more complex models assigning prostate, calcification, and mixtures of prostate and calcification using CT-derived densities. The EGSnrc user-code BrachyDose is employed to calculate dose distributions. All four MAR methods eliminate bright seed spot artifacts, and the image-based methods provide comparable mitigation of artifacts compared with the raw sinogram approach. However, each MAR technique has limitations: STR is unable to mitigate low CT number artifacts, the median filter blurs the image which challenges the preservation of tissue heterogeneities, and both sinogram approaches introduce new streaks. Large local dose differences are generally due to differences in voxel tissue-type rather than mass density. The largest differences in target dose metrics (D90, V100, V150), over 50% lower compared to the other models, are when uncorrected CT images are used with TAS that consider calcifications. Metrics found using models which include calcifications are generally a few percent lower than prostate-only models. Generally, metrics from any MAR method and any TAS which considers calcifications agree within 6%. Overall, the studied MAR methods and TAS show promise for further retrospective MC dose

  7. Development of virtual patient models for permanent implant brachytherapy Monte Carlo dose calculations: interdependence of CT image artifact mitigation and tissue assignment

    International Nuclear Information System (INIS)

    This work investigates and compares CT image metallic artifact reduction (MAR) methods and tissue assignment schemes (TAS) for the development of virtual patient models for permanent implant brachytherapy Monte Carlo (MC) dose calculations. Four MAR techniques are investigated to mitigate seed artifacts from post-implant CT images of a homogeneous phantom and eight prostate patients: a raw sinogram approach using the original CT scanner data and three methods (simple threshold replacement (STR), 3D median filter, and virtual sinogram) requiring only the reconstructed CT image. Virtual patient models are developed using six TAS ranging from the AAPM-ESTRO-ABG TG-186 basic approach of assigning uniform density tissues (resulting in a model not dependent on MAR) to more complex models assigning prostate, calcification, and mixtures of prostate and calcification using CT-derived densities. The EGSnrc user-code BrachyDose is employed to calculate dose distributions. All four MAR methods eliminate bright seed spot artifacts, and the image-based methods provide comparable mitigation of artifacts compared with the raw sinogram approach. However, each MAR technique has limitations: STR is unable to mitigate low CT number artifacts, the median filter blurs the image which challenges the preservation of tissue heterogeneities, and both sinogram approaches introduce new streaks. Large local dose differences are generally due to differences in voxel tissue-type rather than mass density. The largest differences in target dose metrics (D90, V100, V150), over 50% lower compared to the other models, are when uncorrected CT images are used with TAS that consider calcifications. Metrics found using models which include calcifications are generally a few percent lower than prostate-only models. Generally, metrics from any MAR method and any TAS which considers calcifications agree within 6%. Overall, the studied MAR methods and TAS show promise for further retrospective MC dose

  8. High dose rate brachytherapy for oral cancer

    International Nuclear Information System (INIS)

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. (author)

  9. Improved dose calculation accuracy for low energy brachytherapy by optimizing dual energy CT imaging protocols for noise reduction using sinogram affirmed iterative reconstruction.

    Science.gov (United States)

    Landry, Guillaume; Gaudreault, Mathieu; van Elmpt, Wouter; Wildberger, Joachim E; Verhaegen, Frank

    2016-03-01

    The goal of this study was to evaluate the noise reduction achievable from dual energy computed tomography (CT) imaging (DECT) using filtered backprojection (FBP) and iterative image reconstruction algorithms combined with increased imaging exposure. We evaluated the data in the context of imaging for brachytherapy dose calculation, where accurate quantification of electron density ρe and effective atomic number Zeff is beneficial. A dual source CT scanner was used to scan a phantom containing tissue mimicking inserts. DECT scans were acquired at 80 kVp/140Sn kVp (where Sn stands for tin filtration) and 100 kVp/140Sn kVp, using the same values of the CT dose index CTDIvol for both settings as a measure for the radiation imaging exposure. Four CTDIvol levels were investigated. Images were reconstructed using FBP and sinogram affirmed iterative reconstruction (SAFIRE) with strength 1,3 and 5. From DECT scans two material quantities were derived, Zeff and ρe. DECT images were used to assign material types and the amount of improperly assigned voxels was quantified for each protocol. The dosimetric impact of improperly assigned voxels was evaluated with Geant4 Monte Carlo (MC) dose calculations for an (125)I source in numerical phantoms. Standard deviations for Zeff and ρe were reduced up to a factor ∼2 when using SAFIRE with strength 5 compared to FBP. Standard deviations on Zeff and ρe as low as 0.15 and 0.006 were achieved for the muscle insert representing typical soft tissue using a CTDIvol of 40 mGy and 3mm slice thickness. Dose calculation accuracy was generally improved when using SAFIRE. Mean (maximum absolute) dose errors of up to 1.3% (21%) with FBP were reduced to less than 1% (6%) with SAFIRE at a CTDIvol of 10 mGy. Using a CTDIvol of 40mGy and SAFIRE yielded mean dose calculation errors of the order of 0.6% which was the MC dose calculation precision in this study and no error was larger than ±2.5% as opposed to errors of up to -4% with FPB. This

  10. Improved dose calculation accuracy for low energy brachytherapy by optimizing dual energy CT imaging protocols for noise reduction using sinogram affirmed iterative reconstruction

    International Nuclear Information System (INIS)

    The goal of this study was to evaluate the noise reduction achievable from dual energy computed tomography (CT) imaging (DECT) using filtered backprojection (FBP) and iterative image reconstruction algorithms combined with increased imaging exposure. We evaluated the data in the context of imaging for brachytherapy dose calculation, where accurate quantification of electron density ρe and effective atomic number Zeff is beneficial. A dual source CT scanner was used to scan a phantom containing tissue mimicking inserts. DECT scans were acquired at 80 kVp/140Sn kVp (where Sn stands for tin filtration) and 100 kVp/140Sn kVp, using the same values of the CT dose index CTDIvol for both settings as a measure for the radiation imaging exposure. Four CTDIvol levels were investigated. Images were reconstructed using FBP and sinogram affirmed iterative reconstruction (SAFIRE) with strength 1,3 and 5. From DECT scans two material quantities were derived, Zeff and ρe. DECT images were used to assign material types and the amount of improperly assigned voxels was quantified for each protocol. The dosimetric impact of improperly assigned voxels was evaluated with Geant4 Monte Carlo (MC) dose calculations for an 125I source in numerical phantoms. Standard deviations for Zeff and ρe were reduced up to a factor ∝2 when using SAFIRE with strength 5 compared to FBP. Standard deviations on Zeff and ρe as low as 0.15 and 0.006 were achieved for the muscle insert representing typical soft tissue using a CTDIvol of 40 mGy and 3 mm slice thickness. Dose calculation accuracy was generally improved when using SAFIRE. Mean (maximum absolute) dose errors of up to 1.3% (21%) with FBP were reduced to less than 1% (6%) with SAFIRE at a CTDIvol of 10 mGy. Using a CTDIvol of 40mGy and SAFIRE yielded mean dose calculation errors of the order of 0.6% which was the MC dose calculation precision in this study and no error was larger than ±2.5% as opposed to errors of up to -4% with FPB. This

  11. Verification of Oncentra brachytherapy planning using independent calculation

    Science.gov (United States)

    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.

  12. Brachytherapy dose measurements in heterogeneous tissues

    Energy Technology Data Exchange (ETDEWEB)

    Paiva F, G.; Luvizotto, J.; Salles C, T.; Guimaraes A, P. C.; Dalledone S, P. de T.; Yoriyaz, H. [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil); Rubo, R., E-mail: gabrielpaivafonseca@gmail.com [Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo, 05403-900 Sao Paulo (Brazil)

    2014-08-15

    Recently, Beau lieu et al. published an article providing guidance for Model-Based Dose Calculation Algorithms (MBDCAs), where tissue heterogeneity considerations are addressed. It is well-known that T G-43 formalism which considers only water medium is limited and significant dose differences have been found comparing both methodologies. The aim of the present work is to experimentally quantify dose values in heterogeneous medium using different dose measurement methods and techniques and compare them with those obtained with Monte Carlo simulations. Experiments have been performed using a Nucletron micro Selectron-Hdr Ir-192 brachytherapy source and a heterogeneous phantom composed by PMMA and different tissue equivalent cylinders like bone, lungs and muscle. Several dose measurements were obtained using tissue equivalent materials with height 1.8 cm and 4.3 cm positioned between the radiation source and the detectors. Radiochromic films, TLDs and MOSFET S have been used for the dose measurements. Film dosimetry has been performed using two methodologies: a) linearization for dose-response curve based on calibration curves to create a functional form that linearize s the dose response and b) 177 multichannel analysis dosimetry where the multiple color channels are analyzed allowing to address not only disturbances in the measurements caused by thickness variation in the film layer, but also, separate other external influences in the film response. All experiments have been simulated using the MCNP5 Monte Carlo radiation transport code. Comparison of experimental results are in good agreement with calculated dose values with differences less than 6% for almost all cases. (Author)

  13. Brachytherapy dose measurements in heterogeneous tissues

    International Nuclear Information System (INIS)

    Recently, Beau lieu et al. published an article providing guidance for Model-Based Dose Calculation Algorithms (MBDCAs), where tissue heterogeneity considerations are addressed. It is well-known that T G-43 formalism which considers only water medium is limited and significant dose differences have been found comparing both methodologies. The aim of the present work is to experimentally quantify dose values in heterogeneous medium using different dose measurement methods and techniques and compare them with those obtained with Monte Carlo simulations. Experiments have been performed using a Nucletron micro Selectron-Hdr Ir-192 brachytherapy source and a heterogeneous phantom composed by PMMA and different tissue equivalent cylinders like bone, lungs and muscle. Several dose measurements were obtained using tissue equivalent materials with height 1.8 cm and 4.3 cm positioned between the radiation source and the detectors. Radiochromic films, TLDs and MOSFET S have been used for the dose measurements. Film dosimetry has been performed using two methodologies: a) linearization for dose-response curve based on calibration curves to create a functional form that linearize s the dose response and b) 177 multichannel analysis dosimetry where the multiple color channels are analyzed allowing to address not only disturbances in the measurements caused by thickness variation in the film layer, but also, separate other external influences in the film response. All experiments have been simulated using the MCNP5 Monte Carlo radiation transport code. Comparison of experimental results are in good agreement with calculated dose values with differences less than 6% for almost all cases. (Author)

  14. Dose optimisation in single plane interstitial brachytherapy

    DEFF Research Database (Denmark)

    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...

  15. Improved dose calculation accuracy for low energy brachytherapy by optimizing dual energy CT imaging protocols for noise reduction using sinogram affirmed iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Landry, Guillaume [Maastricht University Medical Center (Netherlands). Dept. of Radiation Oncology (MAASTRO); Munich Univ. (Germany). Dept. of Medical Physics; Gaudreault, Mathieu [Maastricht University Medical Center (Netherlands). Dept. of Radiation Oncology (MAASTRO); Laval Univ., QC (Canada). Dept. de Radio-Oncologie et Centre de Recherche en Cancerologie; Laval Univ., QC (Canada). Dept. de Physique, de Genie Physique et d' Optique; Elmpt, Wouter van [Maastricht University Medical Center (Netherlands). Dept. of Radiation Oncology (MAASTRO); Wildberger, Joachim E. [Maastricht University Medical Center (Netherlands). Dept. of Radiology; Verhaegen, Frank [Maastricht University Medical Center (Netherlands). Dept. of Radiation Oncology (MAASTRO); McGill Univ. Montreal, QC (Canada). Dept. of Oncology

    2016-05-01

    The goal of this study was to evaluate the noise reduction achievable from dual energy computed tomography (CT) imaging (DECT) using filtered backprojection (FBP) and iterative image reconstruction algorithms combined with increased imaging exposure. We evaluated the data in the context of imaging for brachytherapy dose calculation, where accurate quantification of electron density ρ{sub e} and effective atomic number Z{sub eff} is beneficial. A dual source CT scanner was used to scan a phantom containing tissue mimicking inserts. DECT scans were acquired at 80 kVp/140Sn kVp (where Sn stands for tin filtration) and 100 kVp/140Sn kVp, using the same values of the CT dose index CTDI{sub vol} for both settings as a measure for the radiation imaging exposure. Four CTDI{sub vol} levels were investigated. Images were reconstructed using FBP and sinogram affirmed iterative reconstruction (SAFIRE) with strength 1,3 and 5. From DECT scans two material quantities were derived, Z{sub eff} and ρ{sub e}. DECT images were used to assign material types and the amount of improperly assigned voxels was quantified for each protocol. The dosimetric impact of improperly assigned voxels was evaluated with Geant4 Monte Carlo (MC) dose calculations for an {sup 125}I source in numerical phantoms. Standard deviations for Z{sub eff} and ρ{sub e} were reduced up to a factor ∝2 when using SAFIRE with strength 5 compared to FBP. Standard deviations on Z{sub eff} and ρ{sub e} as low as 0.15 and 0.006 were achieved for the muscle insert representing typical soft tissue using a CTDI{sub vol} of 40 mGy and 3 mm slice thickness. Dose calculation accuracy was generally improved when using SAFIRE. Mean (maximum absolute) dose errors of up to 1.3% (21%) with FBP were reduced to less than 1% (6%) with SAFIRE at a CTDI{sub vol} of 10 mGy. Using a CTDI{sub vol} of 40mGy and SAFIRE yielded mean dose calculation errors of the order of 0.6% which was the MC dose calculation precision in this study and

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Low dose rate Ir-192 interstitial brachytherapy for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Oki, Yosuke; Dokiya, Takushi; Yorozu, Atsunori; Suzuki, Takayuki; Saito, Shiro; Monma, Tetsuo; Ohki, Takahiro [National Tokyo Medical Center (Japan); Murai, Masaru; Kubo, Atsushi

    2000-04-01

    From December 1997 through January 1999, fifteen prostatic cancer patients were treated with low dose rate Ir-192 interstitial brachytherapy using TRUS and perineal template guidance without external radiotherapy. Up to now, as no apparent side effects were found, the safety of this treatment is suggested. In the future, in order to treat prostatic cancer patients with interstitial brachytherapy using I-125 or Pd-103, more investigation for this low dose rate Ir-192 interstitial brachytherapy is needed. (author)

  18. Brachytherapy treatment with high dose rate

    International Nuclear Information System (INIS)

    Retrospectively analyze results and prognostic factors of cervical cancer patients treated with radio concomitant cisplatin-based chemotherapy, radiation therapy combined modality. Methods: From January 2003 to December 2007, 198 patients with invasive cervical cancer were treated at the Oncology Department of Hospital Robau Celestino Hernandez (brachytherapy performed at INOR). The most common age group was 31 to 40 years. The histology in squamous cell carcinoma accounted for 84.3% of cases. The treatment consisted of external pelvic irradiation and vaginal brachytherapy, high dose rate. Concomitant chemotherapy consisted of cisplatin 40 mg/m2 weekly with a maximum of 70 mg for 5 weeks. Results: 66.2% of patients completed 5 cycles of chemotherapy. The median overall survival was 39 months, overall survival, disease-free survival and survival free of locoregional recurrence at 5 years of 78%, 76% and 78.6% respectively .. We found that clinical stage, histological type (adenocarcinoma worst outcome) were statistically related to level of response. Conclusions: Treatment with external pelvic radiation, brachytherapy and concurrent weekly cisplatin in patients with stage IIIB cervical cancer is feasible in the Chilean public health system, well tolerated and results comparable to international literature. (Author)

  19. [Brachytherapy].

    Science.gov (United States)

    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

  20. Implementation of High Dose Rate Brachytherapy in Limited Resource Settings

    International Nuclear Information System (INIS)

    Brachytherapy is an essential component of the curative treatment of cervical cancer, a disease with high incidence in many developing countries The IAEA supports the use of high dose rate brachytherapy for centres with a large number of patients with this disease. HDR brachytherapy is also used in other common cancers such as breast cancer, lung, oesophagus and prostate. This publication provides guidance to radiation oncologists, medical physicists and planners on establishing and operating a high dose rate brachytherapy unit with modern standards and presents the main issues to be addressed for its effective and safe operation

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

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

    International Nuclear Information System (INIS)

    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)

  6. Preparation of a program for the independent verification of the brachytherapy planning systems calculations

    International Nuclear Information System (INIS)

    In this work a program is presented that independently checks for each patient the treatment planning system calculations in low dose rate, high dose rate and pulsed dose rate brachytherapy. The treatment planning system output text files are automatically loaded in this program in order to get the source coordinates, the desired calculation point coordinates and the dwell times when it is the case. The source strength and the reference dates are introduced by the user. The program allows implementing the recommendations about independent verification of the clinical brachytherapy dosimetry in a simple and accurate way, in few minutes. (Author).

  7. Physics and quality assurance of low dose rate brachytherapy

    International Nuclear Information System (INIS)

    Purpose: The purpose of this course is to review the physical principles underlying design, clinical application and execution of interstitial and intracavitary implants in the classical low dose-rate (LDR) range. This year, the course will focus on quality assurance of sources, applicators and treatment planning software. In addition, development of procedures and QA checks designed optimize treatment delivery accuracy and patient safety during each individual procedure will be reviewed. The level of presentation will be designed to accommodate both physicists and physicians. Implementation of recently published AAPM Task Group reports (no. 40, 'Comprehensive Quality Assurance' and No. 43, 'Dosimetry of Interstitial Brachytherapy Sources') will be reviewed. Outline: (A) General Principles (1) QA endpoints: temporal accuracy, positional accuracy, dose delivery accuracy, and safety of the patient, personnel, and the institution (2) QA procedure development: forms, checklists, test development and design of treatment delivery procedures (B) QA of treatment delivery devices (1) Source acceptance testing and QA a) calibration and source strength specification standards b) leakage tests and source geometry verification (2) Applicator acceptance testing and QA (3) Remote afterloading devices (4) Treatment planning systems a) graphic input/output devices, implant geometry reconstruction, and graphical display b) dose calculation accuracy i) review of brachytherapy dose calculation algorithms ii) dosimetric benchmarks available: Task Group 43 report (C) Procedure-specific QA 1) Organization of treatment delivery team 2) Preplanning and preparation 3) Applicator insertion 4) Radiographic examination of the implant, prescription, and treatment calculation 5) Source insertion 6) Treatment planning and physicist review of treatment plans 7) QA during patient treatment and removal of sources and applicators

  8. A comparison of ICRU point doses and volumetric doses of organs at risk (OARs) in brachytherapy for cervical cancer

    International Nuclear Information System (INIS)

    In brachytherapy for cervix cancer, doses to organs at risk (OARs) are traditionally calculated using the ICRU-38 point doses to rectum and bladder. Three-dimensional image-guided brachytherapy allows assessment of OAR dose with dose volume histograms (DVHs). The purpose of this study was to analyse the correlation between DVHs and ICRU point doses. Using the PLATO™ planning system, the bladder, rectum and sigmoid were retrospectively contoured on 62 CT datasets for 20 patients treated with definitive radiotherapy. The median external beam radiotherapy dose was 45 Gy. Brachytherapy was delivered using a CT-MRI compatible tandem and ovoids to a median dose of 24 Gy in three fractions. DVHs were calculated, and the minimum dose to 2 cc of tissue receiving the highest dose (D2cc) was recorded and compared with the ICRU point doses (DICRU). The mean rectal DICRU was 4.01 Gy compared with D2cc of 4.28 Gy. The mean bladder DICRU was 6.74 Gy compared with D2cc of 8.65 Gy. The mean sigmoid D2cc was 4.58 Gy. The mean dose ratios (D2cc/DICRU) were 1.08 for rectum and 1.39 for bladder. DICRU correlated with D2cc for rectum (r = 0.76, P = 0.001) and for bladder (r = 0.78, P = 0.01). OAR doses assessed by DVH criteria were higher than ICRU point doses. The significant correlation between D2cc and DICRU has allowed us to set DVH dose constraints for CT-based brachytherapy and thus begin the transition from two-dimensional to three-dimensional image-guided brachytherapy planning.

  9. Evaluation of Rectal Dose During High-Dose-Rate Intracavitary Brachytherapy for Cervical Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Sha, Rajib Lochan [Department of Radiation Physics, Indo-American Cancer Institute and Research Centre, Hyderabad (India); Department of Physics, Osmania University, Hyderabad (India); Reddy, Palreddy Yadagiri [Department of Physics, Osmania University, Hyderabad (India); Rao, Ramakrishna [Department of Radiation Physics, MNJ Institute of Oncology and Regional Cancer Center, Hyderabad (India); Muralidhar, Kanaparthy R. [Department of Radiation Physics, Indo-American Cancer Institute and Research Centre, Hyderabad (India); Kudchadker, Rajat J., E-mail: rkudchad@mdanderson.org [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

    2011-01-01

    High-dose-rate intracavitary brachytherapy (HDR-ICBT) for carcinoma of the uterine cervix often results in high doses being delivered to surrounding organs at risk (OARs) such as the rectum and bladder. Therefore, it is important to accurately determine and closely monitor the dose delivered to these OARs. In this study, we measured the dose delivered to the rectum by intracavitary applications and compared this measured dose to the International Commission on Radiation Units and Measurements rectal reference point dose calculated by the treatment planning system (TPS). To measure the dose, we inserted a miniature (0.1 cm{sup 3}) ionization chamber into the rectum of 86 patients undergoing radiation therapy for cervical carcinoma. The response of the miniature chamber modified by 3 thin lead marker rings for identification purposes during imaging was also characterized. The difference between the TPS-calculated maximum dose and the measured dose was <5% in 52 patients, 5-10% in 26 patients, and 10-14% in 8 patients. The TPS-calculated maximum dose was typically higher than the measured dose. Our study indicates that it is possible to measure the rectal dose for cervical carcinoma patients undergoing HDR-ICBT. We also conclude that the dose delivered to the rectum can be reasonably predicted by the TPS-calculated dose.

  10. Dose optimization in simulated permanent interstitial implant of prostate brachytherapy

    International Nuclear Information System (INIS)

    Any treatment of cancer that uses some modality of radiotherapy is planned before being executed. In general the goal in radiotherapy is to irradiate the target to be treated minimizing the incidence of radiation in healthy surrounding tissues. The planning differ among themselves according to the modality of radiotherapy, the type of cancer and where it is located. This work approaches the problem of dose optimization for the planning of prostate cancer treatment through the modality of low dose-rate brachytherapy with Iodine 125 or Palladium 103 seeds. An algorithm for dose calculation and optimization was constructed to find the seeds configuration that better fits the relevant clinical criteria such as as the tolerated dose by the urethra and rectum and the desired dose for prostate. The algorithm automatically finds this configuration from the prostate geometry established in two or three dimensions by using images of ultrasound, magnetic resonance or tomography and from the establishment of minimum restrictions to the positions of the seeds in the prostate and needles in a template. Six patterns of seeds distribution based on clinical criteria were suggested and tested in this work. Each one of these patterns generated a space of possible seeds configurations for the prostate tested by the dose calculation and optimization algorithm. The configurations that satisfied the clinical criteria were submitted to a test according to an optimization function suggested in this work. The configuration that produced maximum value for this function was considered the optimized one. (author)

  11. Integer Programs for High Dose Rate Brachytherapy Needle and Dose Planning that Directly Optimize Clinical Objectives

    OpenAIRE

    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...

  12. I-125 ROPES eye plaque dosimetry: Validation of a commercial 3D ophthalmic brachytherapy treatment planning system and independent dose calculation software with GafChromic{sup ®} EBT3 films

    Energy Technology Data Exchange (ETDEWEB)

    Poder, Joel; Corde, Stéphanie [Department of Radiation Oncology, Prince of Wales Hospital, Randwick, NSW 2031 (Australia)

    2013-12-15

    Purpose: The purpose of this study was to measure the dose distributions for different Radiation Oncology Physics and Engineering Services, Australia (ROPES) type eye plaques loaded with I-125 (model 6711) seeds using GafChromic{sup ®} EBT3 films, in order to verify the dose distributions in the Plaque Simulator™ (PS) ophthalmic 3D treatment planning system. The brachytherapy module of RADCALC{sup ®} was used to independently check the dose distributions calculated by PS. Correction factors were derived from the measured data to be used in PS to account for the effect of the stainless steel ROPES plaque backing on the 3D dose distribution.Methods: Using GafChromic{sup ®} EBT3 films inserted in a specially designed Solid Water™ eye ball phantom, dose distributions were measured three-dimensionally both along and perpendicular to I-125 (model 6711) loaded ROPES eye plaque's central axis (CAX) with 2 mm depth increments. Each measurement was performed in full scatter conditions both with and without the stainless steel plaque backing attached to the eye plaque, to assess its effect on the dose distributions. Results were compared to the dose distributions calculated by Plaque Simulator™ and checked independently with RADCALC{sup ®}.Results: The EBT3 film measurements without the stainless steel backing were found to agree with PS and RADCALC{sup ®} to within 2% and 4%, respectively, on the plaque CAX. Also, RADCALC{sup ®} was found to agree with PS to within 2%. The CAX depth doses measured using EBT3 film with the stainless steel backing were observed to result in a 4% decrease relative to when the backing was not present. Within experimental uncertainty, the 4% decrease was found to be constant with depth and independent of plaque size. Using a constant dose correction factor of T= 0.96 in PS, where the calculated dose for the full water scattering medium is reduced by 4% in every voxel in the dose grid, the effect of the plaque backing was

  13. I-125 ROPES eye plaque dosimetry: Validation of a commercial 3D ophthalmic brachytherapy treatment planning system and independent dose calculation software with GafChromic® EBT3 films

    International Nuclear Information System (INIS)

    Purpose: The purpose of this study was to measure the dose distributions for different Radiation Oncology Physics and Engineering Services, Australia (ROPES) type eye plaques loaded with I-125 (model 6711) seeds using GafChromic® EBT3 films, in order to verify the dose distributions in the Plaque Simulator™ (PS) ophthalmic 3D treatment planning system. The brachytherapy module of RADCALC® was used to independently check the dose distributions calculated by PS. Correction factors were derived from the measured data to be used in PS to account for the effect of the stainless steel ROPES plaque backing on the 3D dose distribution.Methods: Using GafChromic® EBT3 films inserted in a specially designed Solid Water™ eye ball phantom, dose distributions were measured three-dimensionally both along and perpendicular to I-125 (model 6711) loaded ROPES eye plaque's central axis (CAX) with 2 mm depth increments. Each measurement was performed in full scatter conditions both with and without the stainless steel plaque backing attached to the eye plaque, to assess its effect on the dose distributions. Results were compared to the dose distributions calculated by Plaque Simulator™ and checked independently with RADCALC®.Results: The EBT3 film measurements without the stainless steel backing were found to agree with PS and RADCALC® to within 2% and 4%, respectively, on the plaque CAX. Also, RADCALC® was found to agree with PS to within 2%. The CAX depth doses measured using EBT3 film with the stainless steel backing were observed to result in a 4% decrease relative to when the backing was not present. Within experimental uncertainty, the 4% decrease was found to be constant with depth and independent of plaque size. Using a constant dose correction factor of T= 0.96 in PS, where the calculated dose for the full water scattering medium is reduced by 4% in every voxel in the dose grid, the effect of the plaque backing was accurately modeled in the planning system. Off

  14. Dose verification using a pelvic phantom in high dose rate (HDR) brachytherapy

    International Nuclear Information System (INIS)

    High dose rate (HDR) brachytherapy for treating a cervix carcinoma has become popular, because it eliminates many of the problems associated with conventional brachytherapy. In order to improve the clinical effectiveness with HDR brachytherapy, a dose calculation algorithm, optimization procedures, and image registrations need to be verified by comparing the dose distributions from a planning computer and those from a humanoid phantom. In this study, the humanoid phantom was fabricated in order to verify the absolute doses and the relative dose distributions. The measured doses from the humanoid phantom were then compared with the treatment planning system for the dose verification. The humanoid phantom needs to be designed such that the dose distributions can be quantitatively evaluated thermoluminescent dosimeter (TLD) chips with a dimension of 1/8 and film dosimetry with a spatial resolution of <1 mm used to measure the radiation dosages in the phantom. The humanoid phantom called a pelvic phantom was made from water and the tissue-equivalent acrylic plates. In order to firmly hold the HDR applicators in the water phantom, the applicators were inserted into the grooves of the applicator holder. The dose distributions around the applicators, such as Point A and B, were measured by placing a series of TLD chips (TLD-tp-TLD distance: 5mm) in the three TLD holders, and placing three verification films in the orthogonal planes. This study used a Nucletron Plato treatment planning system and a Microselectron Ir-192 source unit. The results showed good agreement between the treatment plan and measurement. The comparisons of the absolute dose showed agreement within 1.48 %-2.95 % of the dose at point A and B, and 2.07 %-3.74 % of the dose at the bladder and rectum point. In addition, the relative dose distributions by film dosimetry and those calculated by the planning computer show good agreement. This pelvic phantom could be a useful to verify the dose calculation

  15. Calculation Monte Carlo equivalent dose to organs in a treatment of prostate with Brachytherapy of high rate; Calculo Monte Carlo de dosis equivalente a organos en un tratamiento de prostata con braquiterapia de alta tasa

    Energy Technology Data Exchange (ETDEWEB)

    Candela-Juan, C.; Vijande, J.; Granero, D.; Ballester, F.; Perez-Calatayud, J.; Rivard, M. J.

    2013-07-01

    The objective of this study was to obtain equivalent dose to radiosensitive organs when applies brachytherapy high dose (HDR) with sources of 60 Co or 192 Go to a localized carcinoma of the prostate. The results are compared with those reported in the literature on treatment with protons and intensity modulated (IMRT) radiation therapy. (Author)

  16. Fricke gel dosimetric catheters in high dose rate brachytherapy. In phantom dose distribution measurements of a 5 catheter implant

    International Nuclear Information System (INIS)

    Due to the complexity and the many steps involved in a high dose rate brachytherapy process, radiation dose delivered to the patient during the treatment is susceptible to many inaccuracies and may not accurately match the planned dose. In vivo dosimetry is a reliable solution to compare planned and delivered dose distributions, representing therefore a valid tool to systematically perform a quality control of the radiotherapic process and eventually increment treatment accuracy. In this study, Fricke gel dosimetric catheters (FGDC) were investigated to perform dose distribution measurements of a brachytherapy implant. The brachytherapy implant was established in a water phantom with five flexible plastic needles and irradiation was performed with a high dose rate remote afterloading device provided with an Ir-192 radioactive source. Comparison between dose distributions measured with ten FGDC located in the proximity of the implant needles and calculated by the treatment planning system shows very good agreement for seven out of ten dosimeters, whereas the remaining three show a local underestimation of the dose. In phantom results indicate that Fricke gel dosimetric catheters might be valid candidates for performing in vivo dosimetry in high dose rate brachytherapy. However, further measurements are still required to validate this dosimetric method.

  17. Brachytherapy

    Science.gov (United States)

    ... 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 ...

  18. Dose determination in breast tumor in brachytherapy using Iridium-192

    International Nuclear Information System (INIS)

    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)

  19. Dose effect of guidewire position in intravascular brachytherapy

    International Nuclear Information System (INIS)

    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)

  20. Remote Afterloading High Dose Rate Brachytherapy AMC EXPERIANCES

    Energy Technology Data Exchange (ETDEWEB)

    Park, Su Gyong; Chang, Hye Sook; Choi, Eun Kyong; Yi, Byong Yong [Ulsan University College of Medicine, Seoul (Korea, Republic of)

    1992-12-15

    Remote afterloading high dose rate brachytherapy(HDRB) is a new technology and needs new biological principle for time and dose schedule. Here, authors attempt to evaluate the technique and clinical outcome in 116 patients, 590 procedures performed at Asan Medical Center for 3 years. From Sep. 1985 to Aug 1992, 471 procedures of intracavitary radiation in 55 patients of cervical cancer and 26 of nasopharyngeal cancer, 79 intraluminal radiation in 12 of esophageal cancer, 11 of endobronchial cancer and 1 Klatskin tumor and 40 interstitial brachytherapy in 4 of breast cancer, 1 sarcoma and 1 urethral cancer were performed. Median follow-up was 7 months with range 1-31 months. All procedures except interstitial were performed under the local anesthesia and they were all well tolerated and completed the planned therapy except 6 patients. 53/58 patients with cervical cancer and 22/26 patients with nasopharynx cancer achieved CR. Among 15 patients with palliative therapy, 80% achieves palliation. We will describe the details of the technique and results in the text. To evaluate biologic effects of HDRB and optimal time/dose/fractionation schedule, we need longer follow-up. But authors feel that HDRB with proper fractionation schedule may yield superior results compared to the low dose rate brachytherapy considering the advantages of HDRB in safety factor for operator, better control of radiation dose and volume and patients comfort over the low dose brachytherapy.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Comparison between calculation methods of dose rates in gynecologic brachytherapy; Comparacion entre metodos de calculo de tasa de dosis en braquiterapia ginecologica8

    Energy Technology Data Exchange (ETDEWEB)

    Vianello, E.A.; Biaggio, M.F.; Dr, M.F.; Almeida, C.E. de [Laboratorio de Ciencias Radiologicas- (L.C.R.)-D.B.B.- UERJ- R. Sao Francisco Xavier, 524- Pav. HLC- sala 136- CEP 20550-013 Rio de Janeiro (Brazil)

    1998-12-31

    In treatments with radiations for gynecologic tumors is necessary to evaluate the quality of the results obtained by different calculation methods for the dose rates on the points of clinical interest (A, rectal, vesicle). The present work compares the results obtained by two methods. The Manual Calibration Method (MCM) tri dimensional (Vianello E., et.al. 1998), using orthogonal radiographs for each patient in treatment, and the Theraplan/T P-11 planning system (Thratonics International Limited 1990) this last one verified experimentally (Vianello et.al. 1996). The results show that MCM can be used in the physical-clinical practice with a percentile difference comparable at the computerized programs. (Author)

  3. Construction balance analysis of dose rate medium brachytherapy TDS

    International Nuclear Information System (INIS)

    One of the most important part of brachytherapy instrument design activities is analyze by determining the centroid point of construction in order to maintain the balance of brachytherapy instrument, either during operation as well as when transported. Operation of brachytherapy is not only done in one place so it is necessary to balance the analysis of the forces at the time did not move, moved on the horizontal floor and sloping floor. Calculation approach who is done to calculate the weight of mechanical components on each module, and then calculate the centroid of each module, for the balance of forces analysis performed with the assumption at the time of brachytherapy in the position of not moving on a horizontal floor, moved from a place to another on the horizontal floor and on the floor with sloping angle 30°. Base on the results of this analysis are expected to balance the four wheels can move without slipping at the time of decline or incline. Also, results of analysis can be used in designing a mobile construction brachytherapy taking into consideration the aesthetic ideal, easy to operate, ensure the safety of equipment, operator and patient. (author)

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

    International Nuclear Information System (INIS)

    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

  5. Boron dose enhancement for Cf-252 brachytherapy

    International Nuclear Information System (INIS)

    Full text: Monte Carlo modelling of a Cf-252 source in water and in tissue has shown that there is a significant therapeutic advantage obtained if B-10 is present in the tumour cells. This study analyses the advantage in terms of therapeutic margin, defined as the distance from the border of the treatment volume where boron-loaded tumour cells will receive a therapeutic dose. Calculations were made with MCNP version 4a on a Pentium 60 MHz computer. Large voxel sizes allowed 70 minute runs to achieve statistical uncertainties of 5% or less for 100,000 source neutrons. Later runs with smaller voxels confirmed the accuracy of the initial calculations. Calculations were made for treatment volume radii up to 11 cm and 30 ppm boron-10. The therapeutic margin for radii in the range 3-9 cm is approximately 10% of the tumour radius. This results in a 30% increase in the volume inside which peripheral tumour cells may receive a therapeutic dose. The median therapeutic ratio within the therapeutic margin varied from 1.05 at 3 cm up to 1.25 at 10 cm. Thus there is little benefit for less advanced tumours with thickness less than 3 cm. However, cervical cancer frequently presents in an advanced state in Southeast Asia and in Aboriginal communities in Australia, partially attributable to low Pap smear screening rates. These conclusions support the development and testing of boron compounds in in vitro and in vivo models for cervical cancer

  6. Brachytherapy Application With In Situ Dose Painting Administered by Gold Nanoparticle Eluters

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Neeharika [Department of Sciences, Wentworth Institute of Technology, Boston, Massachusetts (United States); Cifter, Gizem [Department of Physics and Applied Physics, University of Massachusetts, Lowell, Massachusetts (United States); Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women' s Hospital and Harvard Medical School, Boston, Massachusetts (United States); Sajo, Erno [Department of Physics and Applied Physics, University of Massachusetts, Lowell, Massachusetts (United States); Kumar, Rajiv; Sridhar, Srinivas [Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women' s Hospital and Harvard Medical School, Boston, Massachusetts (United States); Electronic Materials Research Institute and Department of Physics, Northeastern University, Boston, Massachusetts (United States); Nguyen, Paul L.; Cormack, Robert A.; Makrigiorgos, G. Mike [Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women' s Hospital and Harvard Medical School, Boston, Massachusetts (United States); Ngwa, Wilfred, E-mail: wngwa@lroc.harvard.edu [Department of Physics and Applied Physics, University of Massachusetts, Lowell, Massachusetts (United States); Department of Radiation Oncology, Dana-Farber Cancer Institute, Brigham and Women' s Hospital and Harvard Medical School, Boston, Massachusetts (United States)

    2015-02-01

    Purpose: Recent studies show promise that administering gold nanoparticles (GNP) to tumor cells during brachytherapy could significantly enhance radiation damage to the tumor. A new strategy proposed for sustained administration of the GNP in prostate tumors is to load them into routinely used brachytherapy spacers for customizable in situ release after implantation. This in silico study investigated the intratumor biodistribution and corresponding dose enhancement over time due to GNP released from such GNP-loaded brachytherapy spacers (GBS). Method and Materials: An experimentally determined intratumoral diffusion coefficient (D) for 10-nm nanoparticles was used to estimate D for other sizes by using the Stokes-Einstein equation. GNP concentration profiles, obtained using D, were then used to calculate the corresponding dose enhancement factor (DEF) for each tumor voxel, using dose painting-by-numbers approach, for times relevant to the considered brachytherapy sources' lifetimes. The investigation was carried out as a function of GNP size for the clinically applicable low-dose-rate brachytherapy sources iodine-125 (I-125), palladium-103 (Pd-103), and cesium-131 (Cs-131). Results: Results showed that dose enhancement to tumor voxels and subvolumes during brachytherapy can be customized by varying the size of GNP released or eluted from the GBS. For example, using a concentration of 7 mg/g GNP, significant DEF (>20%) could be achieved 5 mm from a GBS after 5, 12, 25, 46, 72, 120, and 195 days, respectively, for GNP sizes of 2, 5, 10, 20, 30, and 50 nm and for 80 nm when treating with I-125. Conclusions: Analyses showed that using Cs-131 provides the highest dose enhancement to tumor voxels. However, given its relatively longer half-life, I-125 presents the most flexibility for customizing the dose enhancement as a function of GNP size. These findings provide a useful reference for further work toward development of potential new brachytherapy application

  7. Brachytherapy Application With In Situ Dose Painting Administered by Gold Nanoparticle Eluters

    International Nuclear Information System (INIS)

    Purpose: Recent studies show promise that administering gold nanoparticles (GNP) to tumor cells during brachytherapy could significantly enhance radiation damage to the tumor. A new strategy proposed for sustained administration of the GNP in prostate tumors is to load them into routinely used brachytherapy spacers for customizable in situ release after implantation. This in silico study investigated the intratumor biodistribution and corresponding dose enhancement over time due to GNP released from such GNP-loaded brachytherapy spacers (GBS). Method and Materials: An experimentally determined intratumoral diffusion coefficient (D) for 10-nm nanoparticles was used to estimate D for other sizes by using the Stokes-Einstein equation. GNP concentration profiles, obtained using D, were then used to calculate the corresponding dose enhancement factor (DEF) for each tumor voxel, using dose painting-by-numbers approach, for times relevant to the considered brachytherapy sources' lifetimes. The investigation was carried out as a function of GNP size for the clinically applicable low-dose-rate brachytherapy sources iodine-125 (I-125), palladium-103 (Pd-103), and cesium-131 (Cs-131). Results: Results showed that dose enhancement to tumor voxels and subvolumes during brachytherapy can be customized by varying the size of GNP released or eluted from the GBS. For example, using a concentration of 7 mg/g GNP, significant DEF (>20%) could be achieved 5 mm from a GBS after 5, 12, 25, 46, 72, 120, and 195 days, respectively, for GNP sizes of 2, 5, 10, 20, 30, and 50 nm and for 80 nm when treating with I-125. Conclusions: Analyses showed that using Cs-131 provides the highest dose enhancement to tumor voxels. However, given its relatively longer half-life, I-125 presents the most flexibility for customizing the dose enhancement as a function of GNP size. These findings provide a useful reference for further work toward development of potential new brachytherapy application

  8. Brachytherapy. Pulsed dose rate brachytherapy - Radiation protection: medical sheet ED 4250

    International Nuclear Information System (INIS)

    After having indicated the required authorization to implement brachytherapy techniques, this document presents the various aspects and measures related to radiation protection when performing pulsed-dose-rate brachytherapy treatments. It presents the concerned personnel, describes the operational process, indicates the associated hazards and the risk related to ionizing radiation, and describes how the risk is to be assessed and how exposure levels are to be determined (elements of risk assessment, delimitation of controlled and monitored areas, personnel classification, and choice of the dose monitoring method). It describes the various components of a risk management strategy (risk reduction, technical measures regarding the installation and the personnel, training and information, prevention and medical monitoring). It briefly presents how risk management is to be assessed, and mentions other related risks (biological risk, handling and posture, handling of heavy loads, mental workload, chemical risk)

  9. Dose volume analysis in brachytherapy and stereotactic radiosurgery

    CERN Document Server

    Tozer-Loft, S M

    2000-01-01

    compared with a range of figures of merit which express different aspects of the quality of each dose distributions. The results are analysed in an attempt to answer the question: What are the important features of the dose distribution (conformality, uniformity, etc) which show a definite relationship with the outcome of the treatment? Initial results show positively that, when Gamma Knife radiosurgery is used to treat acoustic neuroma, some measures of conformality seem to have a surprising, but significant association with outcome. A brief introduction to three branches of radiotherapy is given: interstitial brachytherapy, external beam megavoltage radiotherapy, and stereotactic radiosurgery. The current interest in issues around conformity, uniformity and optimisation is explained in the light of technical developments in these fields. A novel method of displaying dose-volume information, which mathematically suppresses the inverse-square law, as first suggested by L.L. Anderson for use in brachytherapy i...

  10. Pulsed low dose rate brachytherapy for pelvic malignancies

    International Nuclear Information System (INIS)

    Purpose: The pulsed low dose rate remote afterloading unit was designed to combine the radiation safety and isodose optimization advantages of high dose rate technology with the radiobiologic advantages of continuous low dose rate brachytherapy. This is the first report of a prospective clinical trial evaluating the relative incidence of acute toxicity and local control in patients with pelvic malignancies who underwent interstitial or intracavitary brachytherapy with the pulsed low dose rate remote afterloader. Methods and Materials: From 5/11/92-6/21/95, 65 patients underwent 77 brachytherapy procedures as part of their treatment regimen for pelvic malignancies. Using the pulsed low dose rate Selectron, equipped with a single cable-driven 0.3-1.0 Ci Ir192 source, target volume doses of 0.40-0.85 Gy per pulse were prescribed to deliver the clinically determined dose. Forty-five intracavitary and 32 interstitial procedures were performed. Fifty-four patients had primary and 11 recurrent disease. Patients were followed closely to assess incidence of Grade 3-5 acute and delayed toxicity, local control, and survival. Results: With a median follow-up of 16.1 months (range 1-29), 33 patients are NED, 10 alive with disease, 13 dead with disease, 4 dead of intercurrent disease, and 5 lost to follow-up. Local control was maintained until last follow-up or death in 48 cases, local failure occurred in 11, unknown in 5. Grade 3-5 acute toxicities (requiring medical or surgical intervention) occurred in 5 out of 77 procedures (6.5%), delayed complications in 10 patients (15% actuarial incidence at 2 years). In the 52 procedures performed for 42 patients with cervix cancer, the acute toxicity incidence was 5.8%, with a 14% 2-year actuarial incidence of delayed complications. Of 32 interstitial templates performed on 30 patients for pelvic malignancies, there were three incidences of acute toxicity and five delayed toxicities. Conclusion: Using the parameters described for this

  11. Comparison of Dose When Prescribed to Point A and Point H for Brachytherapy in Cervical Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Gang, Ji Hyeong; Gim, Il Hwan; Hwang, Seon Boong; Kim, Woong; Im, Hyeong Seo; Gang, Jin Mook; Gim, Gi Hwan; Lee, Ah Ram [Dept. of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, Seou (Korea, Republic of)

    2012-09-15

    The purpose of this study is to compare plans prescribed to point A with these prescribed to point H recommended by ABS (American Brachytherapy Society) in high dose rate intracavitary brachytherapy for cervical carcinoma. This study selected 103 patients who received HDR (High Dose Rate) brachytherapy using tandem and ovoids from March 2010 to January 2012. Point A, bladder point, and rectal point conform with Manchester System. Point H conforms with ABS recommendation. Also Sigmoid colon point, and vagina point were established arbitrarily. We examined distance between point A and point H. The percent dose at point A was calculated when 100% dose was prescribed to point H. Additionally, the percent dose at each reference points when dose is prescribed to point H and point A were calculated. The relative dose at point A was lower when point H was located inferior to point A. The relative doses at bladder, rectal, sigmoid colon, and vagina points were higher when point H was located superior to point A, and lower when point H was located inferior to point A. This study found out that as point H got located much superior to point A, the absorbed dose of surrounding normal organs became higher, and as point H got located much inferior to point A, the absorbed dose of surrounding normal organs became lower. This differences dose not seem to affect the treatment. However, we suggest this new point is worth being considered for the treatment of HDR if dose distribution and absorbed dose at normal organs have large differences between prescribed to point A and H.

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

    International Nuclear Information System (INIS)

    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.)

  13. Dosimetry Modeling for Focal Low-Dose-Rate Prostate Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Al-Qaisieh, Bashar [Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds (United Kingdom); Mason, Josh, E-mail: joshua.mason@nhs.net [Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds (United Kingdom); Bownes, Peter; Henry, Ann [Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds (United Kingdom); Dickinson, Louise [Division of Surgery and Interventional Science, University College London, London (United Kingdom); Department of Radiology, Northwick Park Hospital, London North West NHS Trust, London (United Kingdom); Ahmed, Hashim U. [Division of Surgery and Interventional Science, University College London, London (United Kingdom); University College London Hospital, London (United Kingdom); Emberton, Mark [University College London Hospital, London (United Kingdom); Langley, Stephen [St Luke' s Cancer Centre, Guildford (United Kingdom)

    2015-07-15

    Purpose: Focal brachytherapy targeted to an individual lesion(s) within the prostate may reduce side effects experienced with whole-gland brachytherapy. The outcomes of a consensus meeting on focal prostate brachytherapy were used to investigate optimal dosimetry of focal low-dose-rate (LDR) prostate brachytherapy targeted using multiparametric magnetic resonance imaging (mp-MRI) and transperineal template prostate mapping (TPM) biopsy, including the effects of random and systematic seed displacements and interseed attenuation (ISA). Methods and Materials: Nine patients were selected according to clinical characteristics and concordance of TPM and mp-MRI. Retrospectively, 3 treatment plans were analyzed for each case: whole-gland (WG), hemi-gland (hemi), and ultra-focal (UF) plans, with 145-Gy prescription dose and identical dose constraints for each plan. Plan robustness to seed displacement and ISA were assessed using Monte Carlo simulations. Results: WG plans used a mean 28 needles and 81 seeds, hemi plans used 17 needles and 56 seeds, and UF plans used 12 needles and 25 seeds. Mean D90 (minimum dose received by 90% of the target) and V100 (percentage of the target that receives 100% dose) values were 181.3 Gy and 99.8% for the prostate in WG plans, 195.7 Gy and 97.8% for the hemi-prostate in hemi plans, and 218.3 Gy and 99.8% for the focal target in UF plans. Mean urethra D10 was 205.9 Gy, 191.4 Gy, and 92.4 Gy in WG, hemi, and UF plans, respectively. Mean rectum D2 cm{sup 3} was 107.5 Gy, 77.0 Gy, and 42.7 Gy in WG, hemi, and UF plans, respectively. Focal plans were more sensitive to seed displacement errors: random shifts with a standard deviation of 4 mm reduced mean target D90 by 14.0%, 20.5%, and 32.0% for WG, hemi, and UF plans, respectively. ISA has a similar impact on dose-volume histogram parameters for all plan types. Conclusions: Treatment planning for focal LDR brachytherapy is feasible. Dose constraints are easily met with a notable

  14. Dosimetry Modeling for Focal Low-Dose-Rate Prostate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: Focal brachytherapy targeted to an individual lesion(s) within the prostate may reduce side effects experienced with whole-gland brachytherapy. The outcomes of a consensus meeting on focal prostate brachytherapy were used to investigate optimal dosimetry of focal low-dose-rate (LDR) prostate brachytherapy targeted using multiparametric magnetic resonance imaging (mp-MRI) and transperineal template prostate mapping (TPM) biopsy, including the effects of random and systematic seed displacements and interseed attenuation (ISA). Methods and Materials: Nine patients were selected according to clinical characteristics and concordance of TPM and mp-MRI. Retrospectively, 3 treatment plans were analyzed for each case: whole-gland (WG), hemi-gland (hemi), and ultra-focal (UF) plans, with 145-Gy prescription dose and identical dose constraints for each plan. Plan robustness to seed displacement and ISA were assessed using Monte Carlo simulations. Results: WG plans used a mean 28 needles and 81 seeds, hemi plans used 17 needles and 56 seeds, and UF plans used 12 needles and 25 seeds. Mean D90 (minimum dose received by 90% of the target) and V100 (percentage of the target that receives 100% dose) values were 181.3 Gy and 99.8% for the prostate in WG plans, 195.7 Gy and 97.8% for the hemi-prostate in hemi plans, and 218.3 Gy and 99.8% for the focal target in UF plans. Mean urethra D10 was 205.9 Gy, 191.4 Gy, and 92.4 Gy in WG, hemi, and UF plans, respectively. Mean rectum D2 cm3 was 107.5 Gy, 77.0 Gy, and 42.7 Gy in WG, hemi, and UF plans, respectively. Focal plans were more sensitive to seed displacement errors: random shifts with a standard deviation of 4 mm reduced mean target D90 by 14.0%, 20.5%, and 32.0% for WG, hemi, and UF plans, respectively. ISA has a similar impact on dose-volume histogram parameters for all plan types. Conclusions: Treatment planning for focal LDR brachytherapy is feasible. Dose constraints are easily met with a notable reduction

  15. Radioactive cloud dose calculations

    International Nuclear Information System (INIS)

    Radiological dosage principles, as well as methods for calculating external and internal dose rates, following dispersion and deposition of radioactive materials in the atmosphere are described. Emphasis has been placed on analytical solutions that are appropriate for hand calculations. In addition, the methods for calculating dose rates from ingestion are discussed. A brief description of several computer programs are included for information on radionuclides. There has been no attempt to be comprehensive, and only a sampling of programs has been selected to illustrate the variety available

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

    International Nuclear Information System (INIS)

    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)

  17. 'In vivo' Dose Measurements in High-Dose-Rate Brachytherapy Treatments for Cervical Cancer: A Project Proposal

    International Nuclear Information System (INIS)

    The aim of this thesis project is to compare doses calculated from the treatment planning system using computed tomography images, with those measured 'in vivo' by using thermoluminescent dosimeters placed at different regions of the rectum and bladder of a patient during high-dose-rate intracavitary brachytherapy treatment of uterine cervical carcinoma. The experimental dosimeters characterisation and calibration have concluded and the protocol to carry out the 'in vivo' measurements has been established. In this work, the calibration curves of two types of thermoluminescent dosimeters (rods and chips) are presented, and the proposed protocol to measure the 'in vivo' dose is fully described.

  18. Current status of high dose rate brachytherapy in cervical cancer in Korea and optimal treatment schedule

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Seung Jae [College of Medicine, Sungkyunkwan Univ., Seoul (Korea, Republic of)

    1998-12-01

    Brachytherapy is an essential part of radiotherapy for uterine cervical cancer. The low dose rate (LDR) regimen has been the major technique of intracavitary therapy for cervical cancer. However, there has been an expansion in the last 20 years of high dose rate (HDR) machines using Ir-192 sources. Since 1979, HDR brachytherapy has been used for the treatment of uterine cervical cancer in Korea. The number of institutions employing HDR has been increasing, while the number of low dose rate system has been constant. In 1995, there was a total 27 HDR brachytherapy units installed and 1258 cases of patients with cervical cancer were treated with HDR. Most common regimens of HDR brachytherapy are total dose of 30-39 Gy at point A with 10-13 fractions in three fractions per week, 24-32 Gy with 6-8 fractions in two fractions per week, and 30-35 Gy with 6-7 fractions in two fractions per week. The average fractionation regimen of HDR brachytherapy is about 8 fractions of 4. 1 Gy each to point A. In Korea, treatment results for HDR brachytherapy are comparable with the LDR series and appears to be a safe and effective alternative to LDR therapy for the treatment of cervical carcinoma. Studies from the major centers report the five-year survival rate of cervical cancer as, 78-86% for Stage I, 68-85% for stage II, and 38-56% for Stage III. World-wide questionnaire study and Japanese questionnaire survey of multiple institutions showed no survival difference in any stages and dose-rate effect ratio (HDR/LDR) was calculated to be 0.54 to 0.58. However, the optimum treatment doses and fractionation schemes appropriate to generate clinical results comparable to conventional LDR schemes have yet to be standardized. In conclusion, HDR intracavitary radiotherapy is increasingly practiced in Korea and an effective treatment modality for cervical cancer. To determine the optimum radiotherapy dose and fractionation schedule, a nation-wide prospective study is necessary in Korea. In

  19. High dose rate brachytherapy for prostate cancer. The first report

    Energy Technology Data Exchange (ETDEWEB)

    Kitano, Masashi; Nishiguchi, Iku; Isobe, Yoshinori; Irie, Akira; Egawa, Shin; Hayakawa, Kazushige [Kitasato Univ., Sagamihara, Kanagawa (Japan). School of Medicine

    2001-09-01

    Iridium-192 high-dose-rate (HDR) brachytherapy may improve local control because of more outstanding dose distribution than external beam radiotherapy in patients with prostate cancer. We report the experience of HDR-brachytherapy for prostate cancer. Between June 1999 and August 2000, forty-five patients with carcinoma of the prostate were treated by using HDR-brachytherapy followed by external beam radiotherapy at Kitasato University East Hospital. T1, 2, 3, T4 and unknown tumors were found in 14, 19, 10, 1 and 1 cases respectively. Using a perineal template, eighteen afterloading needles were inserted to the prostate and seminal vesicle. Then a CT scan was performed to ensure the relationship between needles and the prostate. Treatment volume was defined at 5 mm outside of the capsule of the prostate. Dose prescription was 4 Gy per fraction, and total dose was 20 Gy/5 fractions/3 days. External beam conformal irradiation was then given to the prostate and seminal vesicle to a dose of 30 Gy/10 fractions in two weeks. The median follow-up time was 6.6 months (range, 1.5-14.4 months). Treatment in all patients could be accomplished. No patient experienced acute side-effects of grade 3 or higher. One patient developed a late intestinal side-effect of grade 3. In our institution, because the tips of afterloading needles were inserted through the prostate into the lumen of the bladder, good dose distribution was obtained. It is suggested that this treatment was effective to decrease PSA value and can be safely performed even in old patients. (author)

  20. Radiation safety program in a high dose rate brachytherapy facility

    International Nuclear Information System (INIS)

    The use of remote afterloading equipment has been developed to improve radiation safety in the delivery of treatment in brachytherapy. Several accidents, however, have been reported involving high dose-rate brachytherapy system. These events, together with the desire to address the concerns of radiation workers, and the anticipated adoption of the International Basic Safety Standards for Protection Against Ionizing Radiation (IAEA, 1996), led to the development of the radiation safety program at the Department of Radiotherapy, Jose R. Reyes Memorial Medical Center and at the Division of Radiation Oncology, St. Luke's Medical Center. The radiation safety program covers five major aspects: quality control/quality assurance, radiation monitoring, preventive maintenance, administrative measures and quality audit. Measures for evaluation of effectiveness of the program include decreased unnecessary exposures of patients and staff, improved accuracy in treatment delivery and increased department efficiency due to the development of staff vigilance and decreased anxiety. The success in the implementation required the participation and cooperation of all the personnel involved in the procedures and strong management support. This paper will discuss the radiation safety program for a high dose rate brachytherapy facility developed at these two institutes which may serve as a guideline for other hospitals intending to install a similar facility. (author)

  1. Dose volume analysis in brachytherapy and stereotactic radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Tozer-Loft, S.M

    2000-12-01

    A brief introduction to three branches of radiotherapy is given: interstitial brachytherapy, external beam megavoltage radiotherapy, and stereotactic radiosurgery. The current interest in issues around conformity, uniformity and optimisation is explained in the light of technical developments in these fields. A novel method of displaying dose-volume information, which mathematically suppresses the inverse-square law, as first suggested by L.L. Anderson for use in brachytherapy is explained in detail, and some improvements proposed. These 'natural' histograms are extended to show the effects of real point sources which do not exactly follow the inverse-square law, and to demonstrate the in-target dose-volume distribution, previously unpublished. The histograms are used as a way of mathematically analysing the properties of theoretical mono-energetic radionuclides, and for demonstrating the dosimetric properties of a potential new brachytherapy source (Ytterbium-169). A new modification of the Anderson formalism is then described for producing Anderson Inverse-Square Shifted (AISS) histograms for the Gamma Knife, which are shown to be useful for demonstrating the quality of stereotactic radiosurgery dose distributions. A study is performed analysing the results of Gamma Knife treatments on 44 patients suffering from a benign brain tumour (acoustic neuroma). Follow-up data is used to estimate the volume shrinkage or growth of each tumour, and this measure of outcome is compared with a range of figures of merit which express different aspects of the quality of each dose distributions. The results are analysed in an attempt to answer the question: What are the important features of the dose distribution (conformality, uniformity, etc) which show a definite relationship with the outcome of the treatment? Initial results show positively that, when Gamma Knife radiosurgery is used to treat acoustic neuroma, some measures of conformality seem to have a surprising

  2. A first experience of high dose rate (HDR) brachytherapy for tongue cancer

    International Nuclear Information System (INIS)

    We performed HDR brachytherapy for 12 patients with tongue cancer from April, 1996 to May, 1998. The patients included 7 men and 5 women. Ten of patients received HDR brachytherapy alone and two were treated with HDR brachytherapy and external irradiation and chemotherapy. In brachytherapy alone cases irradiated dose were between 42 Gy/14 fr and 60 Gy/10 fr, and the other two were irradiated 18 Gy/6 fr and 30 Gy/10 fr. We obtained CR for 12 patients and recurrence occurred in three cases. Late injury was observed in one case. In conclusion, HDR brachytherapy will be a promising therapeutic protocol for treatment of stage 1, 2 tongue cancer. (author)

  3. A simple analytical method for heterogeneity corrections in low dose rate prostate brachytherapy

    Science.gov (United States)

    Hueso-González, Fernando; Vijande, Javier; Ballester, Facundo; Perez-Calatayud, Jose; Siebert, Frank-André

    2015-07-01

    In low energy brachytherapy, the presence of tissue heterogeneities contributes significantly to the discrepancies observed between treatment plan and delivered dose. In this work, we present a simplified analytical dose calculation algorithm for heterogeneous tissue. We compare it with Monte Carlo computations and assess its suitability for integration in clinical treatment planning systems. The algorithm, named as RayStretch, is based on the classic equivalent path length method and TG-43 reference data. Analytical and Monte Carlo dose calculations using Penelope2008 are compared for a benchmark case: a prostate patient with calcifications. The results show a remarkable agreement between simulation and algorithm, the latter having, in addition, a high calculation speed. The proposed analytical model is compatible with clinical real-time treatment planning systems based on TG-43 consensus datasets for improving dose calculation and treatment quality in heterogeneous tissue. Moreover, the algorithm is applicable for any type of heterogeneities.

  4. Addendum to brachytherapy dose-volume histogram commissioning with multiple planning systems.

    Science.gov (United States)

    Gossman, Michael S

    2016-01-01

    The process for validating dose-volume histogram data in brachytherapy software is presented as a supplement to a previously published article. Included is the DVH accuracy evaluation of the Best NOMOS treatment planning system called "Best TPS VolumePlan." As done previously in other software, a rectangular cuboid was contoured in the treatment planning system. A single radioactive 125I source was positioned coplanar and concentric with one end. Calculations were performed to estimate dose deposition in partial volumes of the cuboid structure, using the brachytherapy dosimetry formalism defined in AAPM Task Group 43. Hand-calculated, dose-volume results were compared to TPS-generated, point-source-approximated dose-volume histogram data to establish acceptance. The required QA for commissioning was satisfied for the DVH as conducted previously for other software, using the criterion that the DVH %VolTPS "actual variance" calculations should differ by no more than 5% at any specific radial distance with respect to %VolTG-43, and the "average variance" DVH %VolTPS calculations should differ by no more than 2% over all radial distances with respect to %VolTG-43. The average disagreement observed between hand calculations and treatment planning system DVH was less than 0.5% on average for this treatment planning system and less than 1.1% maximally for 1 ≤ r ≤ 5 cm. PMID:27167288

  5. High dose rate vaginal brachytherapy in endometrial cancer after surgery

    International Nuclear Information System (INIS)

    Purpose. - This study aimed at analyzing the evolution and type of recurrence in patients treated for stage I endometrial carcinomas, in order to define the respective roles of adjuvant radiotherapy and brachytherapy. Patients and methods. - This mono-centric retrospective study was conducted at Centre Alexis-Vautrin, Nancy, France, between January 1995 and December 2000 on all the patients surgically treated for an endometrial cancer, and then treated with high dose rate vaginal brachytherapy. The brachytherapy was delivered in two or three fractions of 7 Gy at 5 mm from the applicator. Results. - In the good prognosis group, the specific and overall survivals at 5 years were respectively 96.5 and 94.2% with no local recurrence demonstrated. In the intermediate prognostic group, the specific and overall survivals at 5 years were respectively 88 and 85%, with six locoregional recurrences observed among those who did not undergo lymphadenectomy; the overall survival at 5 years was significantly decreased in the absence of external radiation. In the group of poor prognosis (stages II and III), the specific survival at 5 years was respectively 72.8 and 67 %, and the overall survival at 5 years 66.7 and 56.4%. Conclusion. - Results for local control and survival as well as for tolerance were good. So we have decided to deliver high rate brachytherapy for all intermediate or poor prognosis patients and we have abandoned pelvic radiotherapy for good prognosis tumours (stages IA: no myometrium invasion with grade 3 and >50% of myometrium invasion with grades 1 and 2), whatever the lymph nodes surgery they had. We now propose pelvic radiotherapy only for intermediate prognosis tumours (such as IA > 50% of myometrium invasion with grade 3 and IB stages), if patients did not have any lymphatic surgery, or for bad prognosis tumours. (authors)

  6. Brachytherapy for early oral tongue cancer. Low dose rate to high dose rate

    International Nuclear Information System (INIS)

    To examine the compatibility of low dose rate (LDR) with high dose rate (HDR) brachytherapy, we reviewed 399 patients with early oral tongue cancer (T1-2N0M0) treated solely by brachytherapy at Osaka University Hospital between 1967 and 1999. For patients in the LDR group (n=341), the treatment sources consisted of Ir-192 pin for 227 patients (1973-1996; irradiated dose, 61-85 Gy; median, 70 Gy), Ra-226 needle for 113 patients (1967-1986; 55-93 Gy; median, 70 Gy). Ra-226 and Ir-192 were combined for one patient. Ir-192 HDR (microSelectron-HDR) was used for 58 patients in the HDR group (1991-present; 48-60 Gy; median, 60 Gy). LDR implantations were performed via oral and HDR via a submental/submandibular approach. The dose rates at the reference point for the LDR group were 0.30 to 0.8 Gy/h, and for the HDR group 1.0 to 3.4 Gy/min. The patients in the HDR group received a total dose of 48-60 Gy (8-10 fractions) during one week. Two fractions were administered per day (at least a 6-h interval). The 3- and 5-year local control rates for patients in the LDR group were 85% and 80%, respectively, and those in the HDR group were both 84%. HDR brachytherapy showed the same lymph-node control rate as did LDR brachytherapy (67% at 5 years). HDR brachytherapy achieved the same locoregional result as did LDR brachytherapy. A converting factor of 0.86 is applicable for HDR in the treatment of early oral tongue cancer. (author)

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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

  9. Population dose calculation technique

    International Nuclear Information System (INIS)

    An original method is suggested for calculating the population doses from gas and aerosol radioactive releases. The method is based on the assumption of uniform population and arable land distribution. The validity of this assumption has been proved for a rather large condition range. Though, some modified formulae are given to take into account the non-uniformity of population distribution, connected with large cities, on the one hand, and with woods, shores, regional borders, on the other hand. Employment of the suggested method results in an apriciable calculation accuracy rise for the long-living slowly precipitating radionuclides as compared with the existing methods

  10. Weldon Spring dose calculations

    International Nuclear Information System (INIS)

    In response to a request by the Oak Ridge Operations (ORO) Office of the Department of Energy (DOE) for assistance to the Department of the Army (DA) on the decommissioning of the Weldon Spring Chemical Plant, the Health and Safety Research Division of the Oak Ridge National Laboratory (ORNL) performed limited dose assessment calculations for that site. Based upon radiological measurements from a number of soil samples analyzed by ORNL and from previously acquired radiological data for the Weldon Spring site, source terms were derived to calculate radiation doses for three specific site scenarios. These three hypothetical scenarios are: a wildlife refuge for hunting, fishing, and general outdoor recreation; a school with 40 hr per week occupancy by students and a custodian; and a truck farm producing fruits, vegetables, meat, and dairy products which may be consumed on site. Radiation doses are reported for each of these scenarios both for measured uranium daughter equilibrium ratios and for assumed secular equilibrium. Doses are lower for the nonequilibrium case

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

    International Nuclear Information System (INIS)

    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.

  12. Inter-application displacement of brachytherapy dose received by the bladder and rectum of the patients with inoperable cervical cancer

    International Nuclear Information System (INIS)

    The aim of the study was to examine on the CT basis the inter-application displacement of the positions D0.1cc, D1cc and D2cc of the brachytherapy dose applied to the bladder and rectum of the patients with inoperable cervical cancer. This prospective study included 30 patients with cervical cancer who were treated by concomitant chemo-radiotherapy. HDR intracavitary brachytherapy was made by the applicators type Fletcher tandem and ovoids. For each brachytherapy application the position D0.1cc was determined of the bladder and rectum that receive a brachytherapty dose. Then, based on the X, Y, and Z axis displacement, inter-application mean X, Y, and Z axis displacements were calculated as well as their displacement vectors (R). It has been analyzed whether there is statistically significant difference in inter-application displacement of the position of the brachytherapy dose D0.1cc, D1cc and D2cc of the bladder and rectum. The ANOVA test and post-hoc analysis by Tukey method were used for testing statistical importance of differences among the groups analyzed. The difference among the groups analyzed was considered significant if p < 0.05. There are significant inter-application displacements of the position of the brachytherapy dose D0,1cc, D1cc and D2cc of the bladder and rectum. When we calculate the cumulative brachytherapy dose by summing up D0,1cc, D1cc and D2cc of the organs at risk for all the applications, we must bear in mind their inter-application displacement, and the fact that it is less likely that the worst scenario would indeed happen

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Reirradiation for recurrent head and neck cancer with salvage interstitial pulsed-dose-rate brachytherapy. Long-term results

    International Nuclear Information System (INIS)

    To assess the long-term results of protocol-based interstitial pulsed-dose-rate (PDR) brachytherapy as reirradiation combined with simultaneous chemotherapy and interstitial hyperthermia in selected patients with recurrent head and neck tumors. A total of 104 patients with biopsy-proven recurrent head and neck cancer were treated with interstitial PDR brachytherapy. Salvage surgery had also been undergone by 53/104 (51 %) patients (R1 or R2 resection in > 80 % of patients). Salvage brachytherapy alone was administered in 81 patients (78 %), with a median total dose of 56.7 Gy. Salvage brachytherapy in combination with external beam radiotherapy (EBRT) was performed in 23/104 patients (32 %), using a median total dose of DREF = 24 Gy. Simultaneously to PDR brachytherapy, concomitant chemotherapy was administered in 58/104 (55.8 %) patients. A single session of interstitial hyperthermia was also used to treat 33/104 (31.7 %) patients. The analysis was performed after a median follow-up of 60 months. Calculated according to Kaplan-Meier, local tumor control rates after 2, 5, and 10 years were 92.5, 82.4, and 58.9 %, respectively. Comparing results of salvage PDR brachytherapy with or without simultaneous chemotherapy, the 10-year local control rates were 76 vs. 39 % (p= 0014), respectively. No other patient- or treatment-related parameters had a significant influence on treatment results. Soft tissue necrosis or bone necrosis developed in 18/104 (17.3 %) and 11/104 (9.6 %) patients, respectively, but only 3 % of patients required surgical treatment. PDR interstitial brachytherapy with simultaneous chemotherapy is a very effective and, in experienced hands, also a safe treatment modality in selected patients with head and neck cancer in previously irradiated areas. (orig.)

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  17. Development of a program for calculation of second dose and securities in brachytherapy high dose rate; Elaboracion de un programa para el segundo calculo de la dosis y seguridades en braquiterapia de alta tasa de dosis

    Energy Technology Data Exchange (ETDEWEB)

    Esteve Sanchez, S.; Martinez Albaladejo, M.; Garcia Fuentes, J. D.; Bejar Navarro, M. J.; Capuz Suarez, B.; Moris de Pablos, R.; Colmenares Fernandez, R.

    2015-07-01

    We assessed the reliability of the program with 80 patients in the usual points of prescription of each pathology. The average error of the calculation points is less than 0.3% in 95% of cases, finding the major differences in the axes of the applicators (maximum error -0.798%). The program has proved effective previously testing him with erroneous dosimetry. Thanks to the implementation of this program is achieved by the calculation of the dose and part of the process of quality assurance program in a few minutes, highlighting the case of HDR prostate due to having a limited time. Having separate data sheet allows each institution to its protocols modify parameters. (Author)

  18. Dose calculation in eye brachytherapy with Ir-192 threads using the Sievert integral and corrected by attenuation and scattering with the Meisberg polynomials; Calculo de dosis en braquiterapia ocular con hilos de Ir-192 utilizando la integral de Sievert y cooregida por atenuacion y dispersion con los polinomios de Meisberg

    Energy Technology Data Exchange (ETDEWEB)

    Vivanco, M.G. Bernui de; Cardenas R, A. [Instituto Nacional de Enfermedades Neoplasicas, Universidad Nacional de Ingenieria, Av. Angamos No. 2520, Surquillo, Lima (Peru)]. e-mail: gisellebdv@hotmail.com

    2006-07-01

    The ocular brachytherapy many times unique alternative to conserve the visual organ in patients of ocular cancer, one comes carrying out in the National Institute of Neoplastic Illnesses (INEN) using threads of Iridium 192; those which, they are placed in radial form on the interior surface of a spherical cap of gold of 18 K; the cap remains in the eye until reaching the prescribed dose by the doctor. The main objective of this work is to be able to calculate in a correct and practical way the one time that the treatment of ocular brachytherapy should last to reach the dose prescribed by the doctor. To reach this objective I use the Sievert integral corrected by attenuation effects and scattering (Meisberg polynomials); calculating it by the Simpson method. In the calculations by means of the Sievert integral doesn't take into account the scattering produced by the gold cap neither the variation of the constant of frequency of exposure with the distance. The calculations by means of Sievert integral are compared with those obtained using the Monte Carlo Penelope simulation code, where it is observed that they agree at distances of the surface of the cap greater or equal to 2mm. (Author)

  19. The brachytherapy with low dose-rate iridium for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Momma, Tetsuo; Saito, Shiro; Ohki, Takahiro; Satoh, Hiroyuki; Toya, Kazuhito; Dokiya, Takushi [National Tokyo Medical Center (Japan); Murai, Masaru

    2000-11-01

    Brachytherapy as an option for the treatment of prostate cancer has been commonly performed in USA. As the permanent seeding of the radioactive materials is strictly restricted by the law in Japan, brachytherapy must be performed by the temporary implant. This treatment has been performed at a few facilities in Japan mostly using high dose-rate iridium. Only our facility has been using low dose-rate iridium (LDR-Ir) for prostate cancer. This study evaluates the clinical results of the treatment. Since December 1997 to December 1999, 26 patients with histologically diagnosed as prostate cancer (Stage B, 92%; Stage C, 8%) underwent brachytherapy. Twenty-two patients received brachytherapy alone, three were treated with a combination of brachytherapy and external beam radiotherapy (ERT) and one was treated with a combination of brachytherapy and neoadjuvant endocrine therapy. Patients ranged in age from 61 to 84 (median 76) years old. Treatment was initiated with perineal needle placement. From 10 to 14 needles were placed through the holes on the template which was fixed to the stabilizer of the transrectal ultrasound probe. After the needle placement, CT scan was performed to draw distribution curves for the treatment planning. LDR-Ir wires were introduced to the sheath and indwelled during the time calculated from dosimetry. Peripheral dose was 70 Gy for the monotherapy of brachytherapy. For the combination therapy, 40 Gy was given by brachytherapy and 36 Gy with ERT afterwards. LDR-Ir wires were removed after completion of the radiation and patients were followed with serum PSA level and annual biopsy. During 2 to 26 (median 12) months follow-up, 8 out of 9 patients with initial PSA level above 20 ng/ml showed PSA failure. All 13 patients with initial PSA level lower than 20 ng/ml were free from PSA failure. Eight out of 11 patients with Gleason's score 7 or higher showed PSA failure, and all 14 patients (including three patients with combined therapy) with

  20. Toward endobronchial Ir-192 high-dose-rate brachytherapy therapeutic optimization

    International Nuclear Information System (INIS)

    A number of patients with lung cancer receive either palliative or curative high-dose-rate (HDR) endobronchial brachytherapy. Up to a third of patients treated with endobronchial HDR die from hemoptysis. Rather than accept hemoptysis as an expected potential consequence of HDR, we have calculated the radial dose distribution for an Ir-192 HDR source, rigorously examined the dose and prescription points recommended by the American Brachytherapy Society (ABS), and performed a radiobiological-based analysis. The radial dose rate of a commercially available Ir-192 source was calculated with a Monte Carlo simulation. Based on the linear quadratic model, the estimated palliative, curative and blood vessel rupture radii from the center of an Ir-192 source were obtained for the ABS recommendations and a series of customized HDR prescriptions. The estimated radius at risk for blood vessel perforation for the ABS recommendations ranges from 7 to 9 mm. An optimized prescription may in some situations reduce this radius to 4 mm. The estimated blood perforation radius is generally smaller than the palliative radius. Optimized and individualized endobronchial HDR prescriptions are currently feasible based on our current understanding of tumor and normal tissue radiobiology. Individualized prescriptions could minimize complications such as fatal hemoptysis without sacrificing efficacy. Fiducial stents, HDR catheter centering or spacers and the use of CT imaging to better assess the relationship between the catheter and blood vessels promise to be useful strategies for increasing the therapeutic index of this treatment modality. Prospective trials employing treatment optimization algorithms are needed

  1. Toward endobronchial Ir-192 high-dose-rate brachytherapy therapeutic optimization

    Energy Technology Data Exchange (ETDEWEB)

    Gay, H A [Department of Radiation Oncology, Brody School of Medicine at East Carolina University, Greenville, NC (United States); Allison, R R [Department of Radiation Oncology, Brody School of Medicine at East Carolina University, Greenville, NC (United States); Downie, G H [Section of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC (United States); Mota, H C [Department of Radiation Oncology, Brody School of Medicine at East Carolina University, Greenville, NC (United States); Austerlitz, C [Department of Radiation Oncology, Brody School of Medicine at East Carolina University, Greenville, NC (United States); Jenkins, T [Department of Radiation Oncology, Brody School of Medicine at East Carolina University, Greenville, NC (United States); Sibata, C H [Department of Radiation Oncology, Brody School of Medicine at East Carolina University, Greenville, NC (United States)

    2007-06-07

    A number of patients with lung cancer receive either palliative or curative high-dose-rate (HDR) endobronchial brachytherapy. Up to a third of patients treated with endobronchial HDR die from hemoptysis. Rather than accept hemoptysis as an expected potential consequence of HDR, we have calculated the radial dose distribution for an Ir-192 HDR source, rigorously examined the dose and prescription points recommended by the American Brachytherapy Society (ABS), and performed a radiobiological-based analysis. The radial dose rate of a commercially available Ir-192 source was calculated with a Monte Carlo simulation. Based on the linear quadratic model, the estimated palliative, curative and blood vessel rupture radii from the center of an Ir-192 source were obtained for the ABS recommendations and a series of customized HDR prescriptions. The estimated radius at risk for blood vessel perforation for the ABS recommendations ranges from 7 to 9 mm. An optimized prescription may in some situations reduce this radius to 4 mm. The estimated blood perforation radius is generally smaller than the palliative radius. Optimized and individualized endobronchial HDR prescriptions are currently feasible based on our current understanding of tumor and normal tissue radiobiology. Individualized prescriptions could minimize complications such as fatal hemoptysis without sacrificing efficacy. Fiducial stents, HDR catheter centering or spacers and the use of CT imaging to better assess the relationship between the catheter and blood vessels promise to be useful strategies for increasing the therapeutic index of this treatment modality. Prospective trials employing treatment optimization algorithms are needed.

  2. Postoperative high-dose-rate brachytherapy in the prevention of keloids

    NARCIS (Netherlands)

    Veen, Ronald E.; Kal, Henk B.

    2007-01-01

    Background: The aim of this study is to show the efficiency of keloidectomy and postoperative interstitial high-dose-rate (HDR) brachytherapy in the prevention of keloids. Methods and Materials: Between 1998 and 2004, 35 patients with 54 keloids were treated postoperatively with HDR brachytherapy. T

  3. Gold nanoparticle-aided brachytherapy with vascular dose painting: Estimation of dose enhancement to the tumor endothelial cell nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Ngwa, Wilfred; Makrigiorgos, G. Mike; Berbeco, Ross I. [Department of Radiation Oncology, Division of Medical Physics and Biophysics, Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2012-01-15

    Purpose: Theoretical microdosimetry at the subcellular level is employed in this study to estimate the dose enhancement to tumor endothelial cell nuclei, caused by radiation-induced photo/Auger electrons originating from gold nanoparticles (AuNPs) targeting the tumor endothelium, during brachytherapy. Methods: A tumor vascular endothelial cell (EC) is modeled as a slab of 2 {mu}m (thickness) x 10 {mu}m (length) x 10 {mu}m (width). The EC contains a nucleus of 5 {mu}m diameter and thickness of 0.5-1 {mu}m, corresponding to nucleus size 5%-10% of cellular volume, respectively. Analytic calculations based on the electron energy loss formula of Cole were carried out to estimate the dose enhancement to the nucleus caused by photo/Auger electrons from AuNPs attached to the exterior surface of the EC. The nucleus dose enhancement factor (nDEF), representing the ratio of the dose to the nucleus with and without the presence of gold nanoparticles was calculated for different AuNP local concentrations. The investigated concentration range considers the potential for significantly higher local concentration near the EC due to preferential accumulation of AuNP in the tumor vasculature. Four brachytherapy sources: I-125, Pd-103, Yb-169, and 50 kVp x-rays were investigated. Results: For nucleus size of 10% of the cellular volume and AuNP concentrations ranging from 7 to 140 mg/g, brachytherapy sources Pd-103, I-125, 50 kVp, and Yb-169 yielded nDEF values of 5.6-73, 4.8-58.3, 4.7-56.6, and 3.2-25.8, respectively. Meanwhile, for nucleus size 5% of the cellular volume in the same concentration range, Pd-103, I-125, 50 kVp, and Yb-169 yielded nDEF values of 6.9-79.2, 5.1-63.2, 5.0-61.5, and 3.3-28.3, respectively. Conclusions: The results predict that a substantial dose boost to the nucleus of endothelial cells can be achieved by applying tumor vasculature-targeted AuNPs in combination with brachytherapy. Such vascular dose boosts could induce tumor vascular shutdown, prompting

  4. Demonstration of brachytherapy boost dose-response relationships in glioblastoma multiforme

    International Nuclear Information System (INIS)

    Purpose: To evaluate brachytherapy dose-response relationships in adults with glioblastoma undergoing temporary 125I implant boost after external beam radiotherapy. Methods and Materials: Since June 1987, orthogonal radiographs using a fiducial marker box have been used to verify brain implant source positions and generate dose-volume histograms at the University of California, San Francisco. For adults who underwent brachytherapy boost for glioblastoma from June 1987 through December 1992, tumor volumes were reoutlined to ensure consistency and dose-volume histograms were recalculated. Univariate and multivariate analyses of various patient and treatment parameters were performed evaluating for influence of dose on freedom from local failure (FFLF) and actuarial survival. Results: Of 102 implant boosts, 5 were excluded because computer plans were unavailable. For the remaining 97 patients, analyses with adjustment for known prognostic factors (age, KPS, extent of initial surgical resection) and prognostic factors identified on univariate testing (adjuvant chemotherapy) showed that higher minimum brachytherapy tumor dose was strongly associated with improved FFLF (p = 0.001). A quadratic relationship was found between total biological effective dose and survival, with a trend toward optimal survival probability at 47 Gy minimum brachytherapy tumor dose (corresponding to about 65 Gy to 95% of the tumor volume); survival decreased with lower or higher doses. Two patients expired and one requires hospice care because of brain necrosis after brachytherapy doses > 63 Gy to 95% of the tumor volume with 60 Gy to > 18 cm3 of normal brain. Conclusion: Although higher minimum brachytherapy tumor dose was strongly associated with better local control, a brachytherapy boost dose > 50-60 Gy may result in life-threatening necrosis. We recommend careful conformation of the prescription isodose line to the contrast enhancing tumor volume, delivery of a minimum brachytherapy boost

  5. Erectile dysfunction following treatment with low-dose brachytherapy for prostate cancer

    International Nuclear Information System (INIS)

    Of 260 prostate cancer patients, 26% had potency before brachytherapy when defined as an sexual health inventory for men (SHIM) score of ≥12. Three years after brachytherapy, 44% patients had preserved erectile function (EF-pts) and 56% were erectile dysfunction (ED-pts). Between ED-pts and EF-pts, we compared the doses delivered to the penile bulb or neurovascular bundle using a dose-volume histogram obtained from brachytherapy postplan and patients' characteristics. The mean age and prostate volume of ED-pts were significantly higher than those of EF-pts. No difference was observed in the respective doses between the 2 groups.(author)

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

    Directory of Open Access Journals (Sweden)

    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.

  7. The Transition from 2-D Brachytherapy to 3-D High Dose Rate Brachytherapy

    International Nuclear Information System (INIS)

    Brachytherapy is a major treatment modality in the treatment of common cancers including cervical cancer. This publication addresses the recent technological change in brachytherapy treatment planning with better access to 3-D volumetric patient imaging modalities including computed tomography (CT) and magnetic resonance (MR) as opposed to traditional 2-D planar images. In the context of 2-D and 3-D brachytherapy, the publication provides definitions, clinical indications, transitioning milestones, commissioning steps, quality assurance measures, and a related questionnaire. Staff training and resourcing are also addressed. The publication will serve as a guide to radiotherapy departments in Member States who wish to make the transition from 2-D to 3-D brachytherapy

  8. High dose rate brachytherapy for medically inoperable stage I endometrial cancer

    International Nuclear Information System (INIS)

    Purpose/Objective: To determine the efficacy of high dose rate (HDR) brachytherapy in patients with medically inoperable endometrial cancer clinically confined to the corpus. Materials and Methods: Forty-two patients with endometrial cancer and an intact uterus have been treated since 1989 with HDR brachytherapy. Twenty-six patients with medically inoperable Stage I disease were treated with radiation alone and form the basis of this study. Obesity was assessed using the body mass index (BMI kg/m2) scale. Patients with a BMI above 28 were considered obese and those above 35 morbidly obese, per standard anesthesia guidelines. Brachytherapy was delivered in 5 HDR insertions, 1 week apart, without any external beam radiation. The following doses were delivered per insertion: 5.7 Gy to point S, 7.0 Gy to point W, 8.2 Gy to the vaginal surface and 9.2 Gy to point M. Point M represents the conventional point A dose, while points S and W are myometrial points. A single tandem with either ovoids or cylinders was placed, unless the uterine cavity would accommodate 2 tandems. All treatments were outpatient using intravenous fentanyl and midazolam for sedation. Pelvic ultrasound was commonly used at the time of brachytherapy to verify tandem placement. Three year clinical endpoints were calculated using the Kaplan Meier method. Results: The median follow-up for the study cohort was 21 months with follow-up greater than 36 months in 11 patients. Seventeen of the 26 patients were inoperable due to morbid obesity (median weight and BMI; 316 lbs and 55 kg/m2, respectively); the other patients had poor cardiopulmonary reserve ± obesity. The median age, KPS (Karnofsky Performance Status), weight, ASA (American Society of Anesthesiologists' Physical Class System) and BMI were 63 yrs, 80%, 285 lbs, 3 and 49 kg/m2, respectively. Two patients with an ASA of 3 and 4 died from acute cardio-pulmonary events within 30 days of the last insertion, emphasizing the need for accurate pre

  9. Urethral stricture following high dose rate brachytherapy for prostate cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the incidence, timing, nature and outcome of urethral strictures following high dose rate brachytherapy (HDRB) for prostate carcinoma. Methods and materials: Data from 474 patients with clinically localised prostate cancer treated with HDRB were analysed. Ninety percent received HDRB as a boost to external beam radiotherapy (HDRBB) and the remainder as monotherapy (HDRBM). Urethral strictures were graded according to the Common Terminology Criteria for Adverse Events v3.0. Results: At a median follow-up of 41 months, 38 patients (8%) were diagnosed with a urethral stricture (6-year actuarial risk 12%). Stricture location was bulbo-membranous (BM) urethra in 92.1%. The overall actuarial rate of grade 2 or more BM urethral stricture was estimated at 10.8% (95% CI 7.0-14.9%), with a median time to diagnosis of 22 months (range 10-68 months). All strictures were initially managed with either dilatation (n = 15) or optical urethrotomy (n = 20). Second line therapy was required in 17 cases (49%), third line in three cases (9%) and 1 patient open urethroplasty (grade 3 toxicity). Predictive factors on multivariate analysis were prior trans-urethral resection of prostate (hazard ratio (HR) 2.81, 95% CI 1.15-6.85, p = 0.023); hypertension (HR 2.83, 95% CI 1.37-5.85, p = 0.005); and dose per fraction used in HDR (HR for 1 Gy increase per fraction 1.33, 95% CI 1.08-1.64, p = 0.008). Conclusions: BM urethral strictures are the most common late grade 2 or more urinary toxicity following HDR brachytherapy for prostate cancer. Most are manageable with minimally invasive procedures. Both clinical and dosimetric factors appear to influence the risk of stricture formation.

  10. Biological effective doses in the intracavitary high dose rate brachytherapy of cervical cancer

    Directory of Open Access Journals (Sweden)

    Y. Sobita Devi

    2011-12-01

    Full Text Available Purpose: The aim of this study is to evaluate the decrease of biological equivalent dose and its correlation withlocal/loco-regional control of tumour in the treatment of cervical cancer when the strength of the Ir-192 high dose rate(HDR brachytherapy (BT source is reduced to single, double and triple half life in relation to original strength of10 Ci (~ 4.081 cGy x m2 x h–1. Material and methods: A retrospective study was carried out on 52 cervical cancer patients with stage II and IIItreated with fractionated HDR-BT following external beam radiation therapy (EBRT. International Commission onRadiation Units and Measurement (ICRU points were defined according to ICRU Report 38, using two orthogonal radiographimages taken by Simulator (Simulix HQ. Biologically effective dose (BED was calculated at point A for diffe -rent Ir-192 source strength and its possible correlation with local/loco-regional tumour control was discussed. Result: The increase of treatment time per fraction of dose due to the fall of dose rate especially in HDR-BT of cervicalcancer results in reduction in BED of 2.59%, 7.02% and 13.68% with single, double and triple half life reduction ofsource strength, respectively. The probabilities of disease recurrence (local/loco-regional within 26 months are expectedas 0.12, 0.12, 0.16, 0.39 and 0.80 for source strength of 4.081, 2.041, 1.020, 0.510 and 0.347 cGy x m2 x h–1, respectively.The percentages of dose increase required to maintain the same BED with respect to initial BED were estimated as1.71, 5.00, 11.00 and 15.86 for the dose rate of 24.7, 12.4, 6.2 and 4.2 Gy/hr at point A, respectively. Conclusions: This retrospective study of cervical cancer patients treated with HDR-BT at different Ir-192 sourcestrength shows reduction in disease free survival according to the increase in treatment time duration per fraction.The probable result could be associated with the decrease of biological equivalent dose to point A. Clinical

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

    International Nuclear Information System (INIS)

    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

  12. Reirradiation for recurrent head and neck cancer with salvage interstitial pulsed-dose-rate brachytherapy. Long-term results

    Energy Technology Data Exchange (ETDEWEB)

    Strnad, Vratislav; Lotter, Michael; Kreppner, Stephan; Fietkau, Rainer [University Hospital Erlangen, Dept. of Radiation Oncology, Erlangen (Germany)

    2015-01-10

    To assess the long-term results of protocol-based interstitial pulsed-dose-rate (PDR) brachytherapy as reirradiation combined with simultaneous chemotherapy and interstitial hyperthermia in selected patients with recurrent head and neck tumors. A total of 104 patients with biopsy-proven recurrent head and neck cancer were treated with interstitial PDR brachytherapy. Salvage surgery had also been undergone by 53/104 (51 %) patients (R1 or R2 resection in > 80 % of patients). Salvage brachytherapy alone was administered in 81 patients (78 %), with a median total dose of 56.7 Gy. Salvage brachytherapy in combination with external beam radiotherapy (EBRT) was performed in 23/104 patients (32 %), using a median total dose of D{sub REF} = 24 Gy. Simultaneously to PDR brachytherapy, concomitant chemotherapy was administered in 58/104 (55.8 %) patients. A single session of interstitial hyperthermia was also used to treat 33/104 (31.7 %) patients. The analysis was performed after a median follow-up of 60 months. Calculated according to Kaplan-Meier, local tumor control rates after 2, 5, and 10 years were 92.5, 82.4, and 58.9 %, respectively. Comparing results of salvage PDR brachytherapy with or without simultaneous chemotherapy, the 10-year local control rates were 76 vs. 39 % (p= 0014), respectively. No other patient- or treatment-related parameters had a significant influence on treatment results. Soft tissue necrosis or bone necrosis developed in 18/104 (17.3 %) and 11/104 (9.6 %) patients, respectively, but only 3 % of patients required surgical treatment. PDR interstitial brachytherapy with simultaneous chemotherapy is a very effective and, in experienced hands, also a safe treatment modality in selected patients with head and neck cancer in previously irradiated areas. (orig.) [German] Es erfolgte die Analyse der Langzeitergebnisse einer protokollbasierten interstitiellen Brachytherapie (Re-Bestrahlung) mit simultaner Chemotherapie und interstitieller Hyperthermie

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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. CT based three dimensional dose-volume evaluations for high-dose rate intracavitary brachytherapy for cervical cancer

    Science.gov (United States)

    2014-01-01

    Background In this study, high risk clinical target volumes (HR-CTVs) according to GEC-ESTRO guideline were contoured retrospectively based on CT images taken at the time of high-dose rate intracavitary brachytherapy (HDR-ICBT) and correlation between clinical outcome and dose of HR-CTV were analyzed. Methods Our study population consists of 51 patients with cervical cancer (Stages IB-IVA) treated with 50 Gy external beam radiotherapy (EBRT) using central shield combined with 2–5 times of 6 Gy HDR-ICBT with or without weekly cisplatin. Dose calculation was based on Manchester system and prescribed dose of 6 Gy were delivered for point A. CT images taken at the time of each HDR-ICBT were reviewed and HR-CTVs were contoured. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (α/β = 10 Gy). Results Three-year overall survival, Progression-free survival, and local control rate was 82.4%, 85.3% and 91.7%, respectively. Median cumulative dose of HR-CTV D90 was 65.0 Gy (52.7-101.7 Gy). Median length from tandem to the most lateral edge of HR-CTV at the first ICBT was 29.2 mm (range, 18.0-51.9 mm). On univariate analysis, both LCR and PFS was significantly favorable in those patients D90 for HR-CTV was 60 Gy or greater (p = 0.001 and 0.03, respectively). PFS was significantly favorable in those patients maximum length from tandem to edge of HR-CTV at first ICBT was shorter than 3.5 cm (p = 0.042). Conclusion Volume-dose showed a relationship to the clinical outcome in CT based brachytherapy for cervical carcinoma. PMID:24938757

  16. Study of factors influencing dose distribution of brachytherapy in cervical cancer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Objective To study the factors which influence the dose distribution of brachytherapy in cervical cancer.Methods Ninety-five patients with cervical cancer Ⅱ-Ⅲb received fundamental radiation therapy including brachytherapy in our department from Aug.2004 to Nov.2005.The deviation of isodose curve of brachytherapy was based on A-B reference system,and the deviation of dose was defined by measuring in a practical standard body model.Results The factors influencing isodose offset significantly were parametrial...

  17. Dose rate correction in medium dose rate brachytherapy for carcinoma cervix

    International Nuclear Information System (INIS)

    Purpose: To establish the magnitude of brachytherapy dose reduction required for stage IIB and III carcinoma cervix patients treated by external radiation and medium dose rate (MDR) brachytherapy at a dose rate of 220±10 cGy/h at point A.Materials and methods: In study-I, at the time of MDR brachytherapy application at a dose rate of 220±10 cGy/h at point A, patients received either 3060 cGy, a 12.5% dose reduction (MDR-12.5), or 2450 cGy, a 30% dose reduction (MDR-30), to point A and they were compared to a group of previously treated LDR patients who received 3500 cGy to point A at a dose rate of 55-65 cGy/h. Study-II was a prospective randomized trial and patients received either 2450 cGy, a 30% dose reduction (MDR-II (30)) or 2800 cGy, a 20% dose reduction (MDR-II (20)), at point A. Patients were evaluated for local control of disease and morbidity. Results: In study-I the 5-year actuarial local control rate in the MDR-30 and MDR-12.5 groups was 71.7±10% and 70.5±10%, respectively, compared to 63.4±10% in the LDR group. However, the actuarial morbidity (all grades) in the MDR-12.5 group was 58.5±14% as against 34.9±9% in the LDR group (P3 developed complication as against 62.5% of those receiving a rectal BED of (1403 (χ2=46.43; P<0.001). Conclusion: We suggest that at a dose rate of 220±10 cGy/h at point A the brachytherapy dose reduction factor should be around 30%, as suggested by radiobiological data, to keep the morbidity as low as possible without compromising the local control rates. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  18. Brachytherapy structural shielding calculations using Monte Carlo generated, monoenergetic data

    International Nuclear Information System (INIS)

    Purpose: To provide a method for calculating the transmission of any broad photon beam with a known energy spectrum in the range of 20–1090 keV, through concrete and lead, based on the superposition of corresponding monoenergetic data obtained from Monte Carlo simulation. Methods: MCNP5 was used to calculate broad photon beam transmission data through varying thickness of lead and concrete, for monoenergetic point sources of energy in the range pertinent to brachytherapy (20–1090 keV, in 10 keV intervals). The three parameter empirical model introduced byArcher et al. [“Diagnostic x-ray shielding design based on an empirical model of photon attenuation,” Health Phys. 44, 507–517 (1983)] was used to describe the transmission curve for each of the 216 energy-material combinations. These three parameters, and hence the transmission curve, for any polyenergetic spectrum can then be obtained by superposition along the lines of Kharrati et al. [“Monte Carlo simulation of x-ray buildup factors of lead and its applications in shielding of diagnostic x-ray facilities,” Med. Phys. 34, 1398–1404 (2007)]. A simple program, incorporating a graphical user interface, was developed to facilitate the superposition of monoenergetic data, the graphical and tabular display of broad photon beam transmission curves, and the calculation of material thickness required for a given transmission from these curves. Results: Polyenergetic broad photon beam transmission curves of this work, calculated from the superposition of monoenergetic data, are compared to corresponding results in the literature. A good agreement is observed with results in the literature obtained from Monte Carlo simulations for the photon spectra emitted from bare point sources of various radionuclides. Differences are observed with corresponding results in the literature for x-ray spectra at various tube potentials, mainly due to the different broad beam conditions or x-ray spectra assumed. Conclusions

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, A L [Portsmouth Hospitals NHS Trust, Portsmouth, Hampshire (United Kingdom); University of Surrey, Guildford, Surrey (United Kingdom); Bradley, D A [University of Surrey, Guildford, Surrey (United Kingdom); Nisbet, A [University of Surrey, Guildford, Surrey (United Kingdom); Royal Surrey County Hospital NHS Foundation Trust, Guildford, Surrey (United Kingdom)

    2014-06-01

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

  1. Interstitial high-dose-rate brachytherapy in the treatment of base of tongue carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Takacsi-Nagy, Z.; Polgar, C.; Somogyi, A.; Major, T.; Fodor, J.; Nemeth, G. [Dept. of Radiotherapy, National Inst. of Oncology, Budapest (Hungary); Oberna, F. [Dept. of Maxillofacial Surgery, St. Rokus Hospital, Budapest (Hungary); Remenar, E.; Kasler, M. [Dept. of Head and Neck, Maxillofacial and Reconstructive Plastic Surgery, National Inst. of Oncology, Budapest (Hungary)

    2004-12-01

    Background and purpose: to date none of the studies examined the feasibility and efficacy of interstitial high-dose-rate (HDR) brachytherapy in the treatment of carcinoma of the tongue base. Therefore the aim of this study was to contribute to this issue. Patients and methods: between 1992 and 2000 37 patients (mean age 55 years) with T1-4 and NO-3 carcinoma of the base of tongue were presented. Neck dissection was carried out in twelve cases (32%). 30 patients with advanced stage received brachytherapy boost after 50-66.5 Gy (mean, 60 Gy) locoregional external beam irradiation (EBI) and 7 patients with early stage (T1-2, NO) were managed locally with wide tumor excision and sole brachytherapy. 4 of them underwent neck dissection and the others were subjected to 50 Gy regional EBI. The mean dose of boost and sole brachytherapy was 18 Gy and 28 Gy, respectively. Results: the median follow-up time for surviving patients was 51 months. The 7 sole brachytherapy patients are living with no evidence of disease. For patients treated with EBI and brachytherapy boost, the 5-year actuarial rate of local, locoregional recurrence-free and overall survival was 60%, 52% and 46%, respectively. For all patients in univariate analysis larger tumor size (T4 vs. T1-3) was significant negative predictor of local (RR: 7.23) and locoregional control (RR: 3.87), but nodal involvement was not. Delayed soft tissue ulceration and osteoradionecrosis occurred in 4 (13%) EBI and brachytherapy treated patients. None of the sole brachytherapy patients experienced severe late radiation toxicity. Conclusion: EBI combined with interstitial HDR brachytherapy boost result in acceptable local tumor control with low incidence of late side effects in patients with advanced disease. Fractionated sole HDR brachytherapy following tumor excision is a feasible treatment option for patients with early stage cancer and gives excellent local results. (orig.)

  2. Dose optimization of intra-operative high dose rate interstitial brachytherapy implants for soft tissue sarcoma

    Directory of Open Access Journals (Sweden)

    Jamema Swamidas

    2009-01-01

    Full Text Available Objective : A three dimensional (3D image-based dosimetric study to quantitatively compare geometric vs. dose-point optimization in combination with graphical optimization for interstitial brachytherapy of soft tissue sarcoma (STS. Materials and Methods : Fifteen consecutive STS patients, treated with intra-operative, interstitial Brachytherapy, were enrolled in this dosimetric study. Treatment plans were generated using dose points situated at the "central plane between the catheters", "between the catheters throughout the implanted volume", at "distances perpendicular to the implant axis" and "on the surface of the target volume" Geometrically optimized plans had dose points defined between the catheters, while dose-point optimized plans had dose points defined at a plane perpendicular to the implant axis and on the target surface. Each plan was graphically optimized and compared using dose volume indices. Results : Target coverage was suboptimal with coverage index (CI = 0.67 when dose points were defined at the central plane while it was superior when the dose points were defined at the target surface (CI=0.93. The coverage of graphically optimized plans (GrO was similar to non-GrO with dose points defined on surface or perpendicular to the implant axis. A similar pattern was noticed with conformity index (0.61 vs. 0.82. GrO were more conformal and less homogeneous compared to non-GrO. Sum index was superior for dose points defined on the surface of the target and relatively inferior for plans with dose points at other locations (1.35 vs. 1.27. Conclusions : Optimization with dose points defined away from the implant plane and on target results in superior target coverage with optimal values of other indices. GrO offer better target coverage for implants with non-uniform geometry and target volume.

  3. Inter fraction variations in rectum and bladder volumes and dose distributions during high dose rate brachytherapy treatment of the uterine cervix investigated by repetitive CT-examinations

    International Nuclear Information System (INIS)

    Purpose: To evaluate variation of dose to organs at risk for patients receiving fractionated high dose rate gynaecological brachytherapy by using CT-based 3D treatment planning and dose-volume histograms (DVH). Materials and methods: Fourteen patients with cancer of the uterine cervix underwent three to six CT examinations (mean 4.9) during their course of high-dose-rate brachytherapy using radiographically compatible applicators. The rectal and bladder walls were delineated and DVHs were calculated. Results: Inter fraction variation of the bladder volume (CVmean=44.1%) was significantly larger than the inter fraction variation of the mean dose (CVmean=19.9%, P=0.005) and the maximum dose (CVmean=17.5%, P=0.003) of the bladder wall. The same trend was seen for rectum, although the figures were not significantly different. Performing CT examinations at four of seven brachytherapy fractions reduced the uncertainty to 4 and 7% for the bladder and rectal doses, respectively. A linear regression analysis showed a significant, negative relationship between time after treatment start and the whole bladder volume (P=0.018), whereas no correlation was found for the rectum. For both rectum and bladder a linear regression analysis revealed a significant, negative relationship between the whole volume and median dose (P<0.05). Conclusion: Preferably a CT examination should be provided at every fraction. However, this is logistically unfeasible in most institutions. To obtain reliable DVHs the patients will in the future undergo 3-4 CT examinations during the course of brachytherapy at our institution. Since this study showed an association between large bladder volumes and dose reductions, the patients will be treated with a standardized bladder volume

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

    International Nuclear Information System (INIS)

    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

  5. Medium-dose-rate intracavitary brachytherapy for cervical cancer

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the results of medium-dose-rate (MDR) intracavitary brachytherapy (ICRT) for cervical cancer. Between May 1991 and March 2001, 80 patients with cervical cancer were treated with external radiotherapy combined with MDR-ICRT. Two patients were excluded from this study. The median age of patients was 61 years (range: 30-87 years). Seventy-five patients had pathologically proved squamous cell carcinoma, and 3 had adenocarcinoma. The patients were staged by Union Internationale Contre le Cancer (UICC) classification as follows: Stage IA (2), Stage IB (4), Stage IIA (5), Stage IIB (22), Stage IIIA (1), Stage IIIB (32), Stage IVA (5), Stage IVB (7). Median follow-up for survivor was 68 months (range: 12-131 months). The radiation therapy was based on a combination of ICRT and external pelvic irradiation. Patients with stages II, III and IVA were treated with whole-pelvic irradiation with respective total doses of 20, 30, and 40 Gy. Doses of 40, 30, 20, and 20 Gy parametrial irradiation were added with central shield pelvic irradiation for stages IB, II, III and IVA lesions respectively. For MDR-ICRT, from May 1991 to December 1995, point A dose were 40 Gy/4 fractions for stages I and II, 38 Gy/4 fractions for stage III, and 28.5 Gy/3 fractions for stage IVA. And from January 1996 to March 2001, point A dose of 36 Gy/4 fractions for stages I and II, 34 Gy/4 fractions for stage III, and 25.5 Gy/3 fractions for stage IVA. The median dose rate at point A was 1.7 Gy/hour (range: 1.3-2.2 Gy/hour). The 5-year cause-specific survival rates were 100%, 76%, 51% and 40% for stages I, II, III and IVA respectively. All patients with stage IVB died from the tumor with a median survival time of 12 months. The 5-year pelvic control rates were 100%, 88%, 69% and 40% for stages I, II, III and IVA respectively. Major late complications occurred in 2 patients (3%). One patient developed vesico- and recto-vaginal fistulae, and died of pelvic infection

  6. Feasibility study of patient-specific quality assurance system for high-dose-rate brachytherapy in patients with cervical cancer

    Science.gov (United States)

    Lee, Boram; Ahn, Sung Hwan; Kim, Hyeyoung; Han, Youngyih; Huh, Seung Jae; Kim, Jin Sung; Kim, Dong Wook; Sim, Jina; Yoon, Myonggeun

    2016-04-01

    This study was conducted for the purpose of establishing a quality-assurance (QA) system for brachytherapy that can ensure patient-specific QA by enhancing dosimetric accuracy for the patient's therapy plan. To measure the point-absorbed dose and the 2D dose distribution for the patient's therapy plan, we fabricated a solid phantom that allowed for the insertion of an applicator for patient-specific QA and used an ion chamber and a film as measuring devices. The patient treatment plan was exported to the QA dose-calculation software, which calculated the time weight of dwell position stored in the plan DICOM (Digital Imaging and Communications in Medicine) file to obtain an overall beam quality correction factor, and that correction was applied to the dose calculations. Experiments were conducted after importing the patient's treatment planning source data for the fabricated phantom and inserting the applicator, ion chamber, and film into the phantom. On completion of dose delivery, the doses to the ion chamber and film were checked against the corresponding treatment plan to evaluate the dosimetric accuracy. For experimental purposes, five treatment plans were randomly selected. The beam quality correction factors for ovoid and tandem brachytherapy applicators were found to be 1.15 and 1.10 - 1.12, respectively. The beam quality correction factor in tandem fluctuated by approximately 2%, depending on the changes in the dwell position. The doses measured by using the ion chamber showed differences ranging from -2.4% to 0.6%, compared to the planned doses. As for the film, the passing rate was 90% or higher when assessed using a gamma value of the local dose difference of 3% and a distance to agreement of 3 mm. The results show that the self-fabricated phantom was suitable for QA in clinical settings. The proposed patient-specific QA for the treatment planning is expected to contribute to reduce dosimetric errors in brachytherapy and, thus, to enhancing treatment

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

    International Nuclear Information System (INIS)

    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

  8. Predictors of Toxicity After Image-guided High-dose-rate Interstitial Brachytherapy for Gynecologic Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Larissa J. [Department of Radiation Oncology, Brigham and Women' s Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts (United States); Viswanathan, Akila N., E-mail: aviswanathan@lroc.harvard.edu [Department of Radiation Oncology, Brigham and Women' s Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts (United States)

    2012-12-01

    Purpose: To identify predictors of grade 3-4 complications and grade 2-4 rectal toxicity after three-dimensional image-guided high-dose-rate (HDR) interstitial brachytherapy for gynecologic cancer. Methods and Materials: Records were reviewed for 51 women (22 with primary disease and 29 with recurrence) treated with HDR interstitial brachytherapy. A single interstitial insertion was performed with image guidance by computed tomography (n = 43) or magnetic resonance imaging (n = 8). The median delivered dose in equivalent 2-Gy fractions was 72.0 Gy (45 Gy for external-beam radiation therapy and 24 Gy for brachytherapy). Toxicity was reported according to the Common Toxicity Criteria for Adverse Events. Actuarial toxicity estimates were calculated by the Kaplan-Meier method. Results: At diagnosis, the median patient age was 62 years and the median tumor size was 3.8 cm. The median D90 and V100 were 71.4 Gy and 89.5%; the median D2cc for the bladder, rectum, and sigmoid were 64.6 Gy, 61.0 Gy, and 52.7 Gy, respectively. The actuarial rates of all grade 3-4 complications at 2 years were 20% gastrointestinal, 9% vaginal, 6% skin, 3% musculoskeletal, and 2% lymphatic. There were no grade 3-4 genitourinary complications and no grade 5 toxicities. Grade 2-4 rectal toxicity was observed in 10 patients, and grade 3-4 complications in 4; all cases were proctitis with the exception of 1 rectal fistula. D2cc for rectum was higher for patients with grade 2-4 (68 Gy vs 57 Gy for grade 0-1, P=.03) and grade 3-4 (73 Gy vs 58 Gy for grade 0-2, P=.02) rectal toxicity. The estimated dose that resulted in a 10% risk of grade 2-4 rectal toxicity was 61.8 Gy (95% confidence interval, 51.5-72.2 Gy). Discussion: Image-guided HDR interstitial brachytherapy results in acceptable toxicity for women with primary or recurrent gynecologic cancer. D2cc for the rectum is a reliable predictor of late rectal complications. Three-dimensional-based treatment planning should be performed to ensure

  9. Outcomes of low-dose-rate brachytherapy for treatment of tongue cancer

    International Nuclear Information System (INIS)

    Between 1997 and 2006, 324 patients with T1-2 tongue cancer were treated with low-dose-rate brachytherapy at Tokyo Medical and Dental University Hospital. Their 5- and 10-year local control rates were 83% and 80%, respectively, and the occurrence rates of ≥ grade 3 mucositis and osteonecrosis were both 0.3%. During the study period, 9 other patients with tongue cancer underwent surgery and brachytherapy for positive surgical margins at our institution. Their 5- and 10-year local control rates were 76% and 64%. Moreover, 24 patients with tongue cancer received chemotherapy followed by brachytherapy, and their 5- and 10-year local control rates were both 100%. These outcomes are comparable to those of the patients who underwent low-dose-rate brachytherapy for T1-2 tongue cancer. In this study, 80% of patients treated by brachytherapy for T1-2 tongue cancer were cured with preserved function. However, for some patients with tumors unsuitable for treatment by brachytherapy alone, a combination of brachytherapy and surgery or chemotherapy may be a suitable treatment option. (author)

  10. LOW-DOSE RATE BRACHYTHERAPY FOR PROSTATE CANCER: DIFFERENT INDICATIONS – DIFFERENT RESULTS

    Directory of Open Access Journals (Sweden)

    V. A. Biryukov

    2014-07-01

    Full Text Available In Russia, there is presently a growing interest in low-dose intratissue radiotherapy (brachytherapy for locally advanced prostate cancer (PC. Since its inception, current brachytherapy has undergone a number of significant changes in terms of improved visualization and better treatment planning and monitoring, which is sure to have affected the higher quality of their performance and better long-term results. The main purpose of the given paper is to generalize the data of foreign investigators who have the greatest experience with brachytherapy for its further use in the treatment of patients with locally advanced PC under the conditions of Russian clinics.

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

    International Nuclear Information System (INIS)

    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)

  12. A comparison of radiation dose to the neurovascular bundles in men with and without prostate brachytherapy-induced erectile dysfunction

    International Nuclear Information System (INIS)

    Purpose: The etiology of erectile dysfunction after definitive local therapy for carcinoma of the prostate gland represents a multifactorial phenomenon including neurogenic compromise, venous insufficiency, local trauma, and psychogenic causes. It has been suggested that impotence after prostate brachytherapy is a consequence of excessive radiation dose to the neurovascular bundles (NVB). Herein we evaluate the potential relationship between radiation dose to the NVB and the development of erectile dysfunction following prostate brachytherapy. Methods and Materials: The radiation dose to the NVB was evaluated for 33 patients who developed erectile dysfunction (ED) following brachytherapy plus 21 additional patients who were potent before and subsequent to brachytherapy. Of the 54 patient study group, the median follow up was 37 months, and 25 patients were managed with 125I as a monotherapeutic approach and 29 received 103Pd as a boost following 45 Gy of external beam radiation therapy. Radiographic localization of the NVB was performed via a two-dimensional geometric model that placed 3-NVB calculation points on the left and right posterolateral side of each 5-mm CT slice. Parameters evaluated included dose-surface histograms, dose parameters via point doses on each slice, the magnitude of the dose in relationship to the distance from the base, and the relationship between NVB radiation dose in patients with and without ED, patient response to sildenafil and case sequence number. Results: In terms of percent prescribed minimum peripheral dose (% mPD), there was no significant difference in mean neurovascular bundle dose between potent and impotent patients, between the isotopes (125I or 103Pd), mono- or boost therapy, or side of the prostate for which the overall average was 217% ± 55% of mPD. There was also no significant dosimetric difference in terms of response to sildenafil based on a multivariate analysis which included % mPD and various dose thresholds and

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

    Directory of Open Access Journals (Sweden)

    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

  14. SU-E-T-477: An Efficient Dose Correction Algorithm Accounting for Tissue Heterogeneities in LDR Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mashouf, S; Lai, P [University of Toronto, Medical Biophysics Dept., Toronto, ON (Canada); Karotki, A; Keller, B; Beachey, D; Pignol, J [Sunnybrook Health Sciences Centre, Toronto, ON (Canada)

    2014-06-01

    Purpose: Seed brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose surrounding the brachytherapy seeds is based on American Association of Physicist in Medicine Task Group No. 43 (TG-43 formalism) which generates the dose in homogeneous water medium. Recently, AAPM Task Group No. 186 emphasized the importance of accounting for tissue heterogeneities. This can be done using Monte Carlo (MC) methods, but it requires knowing the source structure and tissue atomic composition accurately. In this work we describe an efficient analytical dose inhomogeneity correction algorithm implemented using MIM Symphony treatment planning platform to calculate dose distributions in heterogeneous media. Methods: An Inhomogeneity Correction Factor (ICF) is introduced as the ratio of absorbed dose in tissue to that in water medium. ICF is a function of tissue properties and independent of source structure. The ICF is extracted using CT images and the absorbed dose in tissue can then be calculated by multiplying the dose as calculated by the TG-43 formalism times ICF. To evaluate the methodology, we compared our results with Monte Carlo simulations as well as experiments in phantoms with known density and atomic compositions. Results: The dose distributions obtained through applying ICF to TG-43 protocol agreed very well with those of Monte Carlo simulations as well as experiments in all phantoms. In all cases, the mean relative error was reduced by at least 50% when ICF correction factor was applied to the TG-43 protocol. Conclusion: We have developed a new analytical dose calculation method which enables personalized dose calculations in heterogeneous media. The advantages over stochastic methods are computational efficiency and the ease of integration into clinical setting as detailed source structure and tissue segmentation are not needed. University of Toronto, Natural Sciences and

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

    Science.gov (United States)

    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

  16. Time, dose and volume factors in interstitial brachytherapy combined with external irradiation for oral tongue carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Yorozu, Atsunori [National Tokyo Second Hospital (Japan)

    1996-04-01

    This is a retrospective analysis of 136 patients with squamous cell carcinoma of stages I and II of the oral tongue who were treated with interstitial brachytherapy alone or in combination with external irradiation between 1976 and 1991. Control of the primary lesion and the occurrence of late complications were analyzed with respect to dose, time and tumor size with the Cox hazard model. The 5-year survival rates for stages I and II were 84.5% and 75.6%. The 5-year primary control rate was 91.3% for stage I and 77.3% for stage II (p<0.05). Local control and survival rates were comparable with those of other modalities. The significant factor in local control was stage. For lesions more than 30 mm in diameter, local control was rather poor in the group given only brachytherapy compared with the group given combined therapy. After 30 Gy of external irradiation, local control was better at a brachytherapy dose >50 Gy compared with a brachytherapy dose <=50 Gy. Mucosal ulcer occurred frequently with increasing total dose and tumor volume. Bone necrosis increased significantly with increasing external irradiation dose. We suggest that external irradiation of 30 Gy followed by brachytherapy of 52 Gy is a better choice for T2 lesions >30 mm. Late complications should be reduced by using a spacer, improvements in dental and oral hygiene, and a sophisticated implant method. (author).

  17. Endobronchial and endoesophageal high dose rate brachytherapy for malignant airway and digestive tract obstructions

    International Nuclear Information System (INIS)

    Purpose/Objective: High dose rate brachytherapy has had a rapid increase in use for endo-luminal treatment especially in tracheobronchial and esophageal carcinoma. The increase in utilization of this modality has outpaced the development of treatment indications, standardization of dose prescription and specification, and reporting of outcome. The course will address these issues. Treatment of endobronchial carcinoma by high dose rate brachytherapy will be discussed covering a survey of low dose, medium dose, and high dose rate treatments reported in the literature to provide prospective. Indications, treatment protocol and results of the author for HDR (including 47 patients treated with medium dose rate) will be discussed, covering more than 500 patients treated on dose searching protocols. Results will include improvement in obstruction (using the obstruction score), symptoms (using the fourtiered symptom complex scores), recurrence patterns, oxygen saturation, performance status, and survival (including cause of death). Complications discussed will be immediate i.e., pneumothorax, and delayed such as fatal hemoptysis, and radiation bronchitis/stenosis. Treatment recommendations for radiation bronchitis/stenosis will be covered. Esophageal brachytherapy for more than 100 patients will be discussed. Procedure, treatment protocols for palliative treatment (both initial disease and recurrence) and for curative intent will be discussed. The curative intent protocol consists of radiation only (external and endoluminal) vs radiation and chemotherapy (reduced dose of external with concurrent 5-FU + Cis-Platinum), then endoluminal brachytherapy. For curative patients, results will include survival and long term complications. Treatment complications to be discussed include perforation, stricture and ulceration

  18. Modelling radiation doses to critical organs of patients undergoing intracavitary brachytherapy treatment at Kumfo Anokye Teaching Hospital

    International Nuclear Information System (INIS)

    The main aim of radiotherapy is to destroy cancerous tissues with ionizing radiation while the other normal parts of the body are saved or spared. Intracavitary brachytherapy is a procedure in which radioactive sources are placed in the body cavities close to or inside the target volume to deliver radiation at short distances. In this mode of treatment, high radiation dose can be delivered to the tumour volume with rapid dose fall-off into the surrounding normal tissues. In brachytherapy, the dosimetry in biological tissues is a complex process. Dosimetric parameters such as the dose to critical organs and the total dose to the reference points as in the case of Manchester system are critical for patients undergoing intracavitary brachytherapy treatment. In this study, the Finite Element Method (FEM) has been utilized to solve Boltzmann Transport Equation (BTE) to determine the distribution of angular photon fluxes at various positions in the cervix of cancer patients and the dose distribution calculated for the organs of interest. The time-dependent linear BTE was used to describe the passage of ionizing radiation taking into account tissue heterogeneities and other scattering phenomena before depositing the absorbed dose in a patient. The simulation was carried out to determine doses to the critical organs, namely the rectum and bladder. Results from the study indicate doses to the rectum and the bladder to be in the range of 10.13-85.67cGy and 21.32-78.81cGy respectively for stage I to stage IV cancer patients. Comparison of the results from the model with data from published articles and dose prescriptions from the treatment planning system of the Radiotherapy Center of the Komfo Anokye Teaching Hospital in Ghana for different cancer stages indicate good agreement with standard error of ±20% to ±34%. (au)

  19. WE-A-17A-04: Development of An Ultra-Fast Monte Carlo Dose Engine for High Dose Rate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: Current clinical brachytherapy dose calculations are based on AAPM TG43 guidelines, which approximate the patient geometry as a large water phantom. This ignores heterogeneities and tends to overestimate skin dose. Although Monte Carlo (MC) dose calculations have been recognized as the most accurate method, its associated long computational time is a major bottleneck for routine clinical applications. This work aims to develop a GPU-based ultra-fast MC dose engine (gBMC) for HDR brachytherapy to provide clinical users with accurate sub-minute dose calculations. Methods: Standard photon transport with discrete events including: Compton scattering, Rayleigh scattering and Photoelectric effect, was implemented. Secondary electrons were transported under the continuous slowing down approximation. To reduce the GPU thread divergence, photons and electrons were separately transported. Transport of photons was grouped according to energy. The source model in gBMC can be either a phase-space file generated using Geant4 or a parameterized source model. This dose engine was validated against TG43 in a water phantom and against Geant4 calculations in heterogeneous patient geometries. Results: A phase space file was generated for the Varian VS2000 Ir-192 source. In a water phantom, the calculated radial dose function was within 0.6% of the TG43 calculations for radial distances from 1 cm to 20 cm. The anisotropy functions were within 1% for radial distances from 1 cm to 20 cm except for polar angles larger than 173°. Local point-dose differences were within 2%. In a Mammosite breast cancer case with 22 dwell locations, gBMC and Geant4 isodose lines compared well. The computation time was about 28 seconds using the phase-space file source and 20 seconds using the parameterized source to simulate 1 billion particles, yielding less than 1% statistical uncertainty. Conclusion: The gBMC dose engine makes it possible to use fast and accurate MC dose calculations for

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  2. Determination of the dose of traffic in HDR brachytherapy with ALANINE/R PE technique

    International Nuclear Information System (INIS)

    It determines, experimentally, the dose of traffic in brachytherapy for High Dose Rate (HDR), using for the first-time the Electronic Paramagnetic Resonance (EPR) technique with alanine detectors. The value obtained is the published next to obtained using lithium fluoride thermoluminescent dosimeters

  3. High dose rate brachytherapy in the treatment of endometrium carcinoma

    International Nuclear Information System (INIS)

    One hundred and four patients with histologic proven carcinoma of the endometrium were referred to our department for treatment. The median age was 65.5 years and the median follow-up was 38 months. Ninety-five was pos-menopaused, 7 peri and 2 were pre-menopaused. Sixteen patients were staged (pos-surgery) IA, 5 GI, 8 G2 and 3 G3. Thirty and four stage IB, 10 G1, 18 G2 and 1 G3. Twenty-five were stage IC, 9 G1, 9 G2 and 7 G3. Six were stage IIA, 2 GI, 3 G2 and 1 G3. Eight were stages IIB, 1 G1,3 G2 and 4 G3. Nine were stage IIA, 2 GI, 5 G2, 2 G3. Three were stage IIIB, 2 GI and 1 G2. One was stage III C G3, and two were IVA G3. Depending of the extension of the disease, patients underwent total hysterectomy and bilateral salpino-ooforectomy, or total hysterectomy and bilateral salpino-ooforectomy plus omentectomy or Werthein-Megs technique. All the patients IA and IB have no evidence of disease (NED). Twenty-four patients IC are NED and one presented distant metastasis. From the IIB patients, 6 are NED, one shown progressive local disease (PLD) and one died from disease. From the patients IIIA, 7 are NED, one DM and one PLD. From the IIIB patients one is NED and TWO are PLD. From the IIIC patient is NED two months after treatment and the IVA patients are NED three and four month after treatment. Eight patients have shown mild complications of treatment. The results of survival and complications are similar to the therapeutic with low dose rate brachytherapy, with the advantage of an outpatient treatment, without the inconvenience of impatient regime. (author)

  4. Maximum and mean bladder dose defined from ultrasonography. Comparison with the ICRU reference in gynaecological brachytherapy

    International Nuclear Information System (INIS)

    The reference bladder dose for gynaecological intracavitary brachytherapy (BT), as defined by the ICRU 38 Report, is often criticised as it is seldom representative of the highest bladder dose nor it gives an idea of the area exposed to a significant dose. Since November 1990, ultrasound measurements are routinely made in order to determine the actual dose delivered to the bladder of each patient. The technique was as follows. (1) the bladder is filled up with 150-200 cm3 of sterile isotonic saline. (2) The intra-uterine position of the tube is checked. (3) The bladder anatomy is controlled. (4) Points of measurements are identified: ICRU bladder reference, minimum distance between bladder mucosa, uterine tube and other similar measurements taken ever 15 mm along the radio-active line. Maximum and mean doses are calculated at the sagittal plane. Measurements are performed by moving the transducer along the skin of the patient and included in the calculation of dose distribution. Doses delivered to each relevant point are compared. This enables determination to be made of the differences between the ICRU and the doses actually observed at the bladder wall with aid of ultrasonography. BT applications were checked in 58 patients (69 measurements). The method was feasible in all cases. The comparison between ICRU dose from orthogonal films and the ICRU dose from ultrasonography resulted in a 90% accuracy. The maximum and mean doses for utero-vaginal BT are higher than the ICRU dose in 75% of cases (range, 2-8). Measurements are now abandoned for vaginal applications as the ICRU dose only could be measured. A single G3 complication was observed after 20 months in a patient in whom a high bladder dose was planned intentionally. The conclusion is that it is expected that this new approach will be of help to decrease the rate of severe complications by pointing out those patients in which there is a large discrepancy between the ICRU dose and doses determined with aid of

  5. Reporting small bowel dose in cervix cancer high-dose-rate brachytherapy.

    Science.gov (United States)

    Liao, Yixiang; Dandekar, Virag; Chu, James C H; Turian, Julius; Bernard, Damian; Kiel, Krystyna

    2016-01-01

    Small bowel (SB) is an organ at risk (OAR) that may potentially develop toxicity after radiotherapy for cervix cancer. However, its dose from brachytherapy (BT) is not systematically reported as in other OARs, even with image-guided brachytherapy (IGBT). This study aims to introduce consideration of quantified objectives for SB in BT plan optimization and to evaluate the feasibility of sparing SB while maintaining adequate target coverage. In all, 13 patients were included in this retrospective study. All patients were treated with external beam radiotherapy (EBRT) 45Gy in 25 fractions followed by high dose rate (HDR)-BT boost of 28Gy in 4 fractions using tandem/ring applicator. Magnetic resonance imaging (MRI) and computed tomographic (CT) images were obtained to define the gross tumor volume (GTV), high-risk clinical target volume (HR-CTV) and OARs (rectum, bladder, sigmoid colon, and SB). Treatment plans were generated for each patient using GEC-ESTRO recommendations based on the first CT/MRI. Treatment plans were revised to reduce SB dose when the [Formula: see text] dose to SB was > 5Gy, while maintaining other OAR constraints. For the 7 patients with 2 sets of CT and MRI studies, the interfraction variation of the most exposed SB was analyzed. Plan revisions were done in 6 of 13 cases owing to high [Formula: see text] of SB. An average reduction of 19% in [Formula: see text] was achieved. Meeting SB and other OAR constraints resulted in less than optimal target coverage in 2 patients (D90 of HR-CTV < 77Gyαβ10). The highest interfraction variation was observed for SB at 16 ± 59%, as opposed to 28 ± 27% for rectum and 21 ± 16% for bladder. Prospective reporting of SB dose could provide data required to establish a potential correlation with radiation-induced late complication for SB. PMID:26235549

  6. Metallic artifact mitigation and organ-constrained tissue assignment for Monte Carlo calculations of permanent implant lung brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, J. G. H.; Miksys, N.; Thomson, R. M., E-mail: rthomson@physics.carleton.ca [Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Furutani, K. M. [Department of Radiation Oncology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905 (United States)

    2014-01-15

    Purpose: To investigate methods of generating accurate patient-specific computational phantoms for the Monte Carlo calculation of lung brachytherapy patient dose distributions. Methods: Four metallic artifact mitigation methods are applied to six lung brachytherapy patient computed tomography (CT) images: simple threshold replacement (STR) identifies high CT values in the vicinity of the seeds and replaces them with estimated true values; fan beam virtual sinogram replaces artifact-affected values in a virtual sinogram and performs a filtered back-projection to generate a corrected image; 3D median filter replaces voxel values that differ from the median value in a region of interest surrounding the voxel and then applies a second filter to reduce noise; and a combination of fan beam virtual sinogram and STR. Computational phantoms are generated from artifact-corrected and uncorrected images using several tissue assignment schemes: both lung-contour constrained and unconstrained global schemes are considered. Voxel mass densities are assigned based on voxel CT number or using the nominal tissue mass densities. Dose distributions are calculated using the EGSnrc user-code BrachyDose for{sup 125}I, {sup 103}Pd, and {sup 131}Cs seeds and are compared directly as well as through dose volume histograms and dose metrics for target volumes surrounding surgical sutures. Results: Metallic artifact mitigation techniques vary in ability to reduce artifacts while preserving tissue detail. Notably, images corrected with the fan beam virtual sinogram have reduced artifacts but residual artifacts near sources remain requiring additional use of STR; the 3D median filter removes artifacts but simultaneously removes detail in lung and bone. Doses vary considerably between computational phantoms with the largest differences arising from artifact-affected voxels assigned to bone in the vicinity of the seeds. Consequently, when metallic artifact reduction and constrained tissue

  7. Imaging method for monitoring delivery of high dose rate brachytherapy

    Science.gov (United States)

    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.

  8. High-dose-rate prostate brachytherapy inverse planning on dose-volume criteria by simulated annealing

    Science.gov (United States)

    Deist, T. M.; Gorissen, B. L.

    2016-02-01

    High-dose-rate brachytherapy is a tumor treatment method where a highly radioactive source is brought in close proximity to the tumor. In this paper we develop a simulated annealing algorithm to optimize the dwell times at preselected dwell positions to maximize tumor coverage under dose-volume constraints on the organs at risk. Compared to existing algorithms, our algorithm has advantages in terms of speed and objective value and does not require an expensive general purpose solver. Its success mainly depends on exploiting the efficiency of matrix multiplication and a careful selection of the neighboring states. In this paper we outline its details and make an in-depth comparison with existing methods using real patient data.

  9. High-dose-rate prostate brachytherapy inverse planning on dose-volume criteria by simulated annealing.

    Science.gov (United States)

    Deist, T M; Gorissen, B L

    2016-02-01

    High-dose-rate brachytherapy is a tumor treatment method where a highly radioactive source is brought in close proximity to the tumor. In this paper we develop a simulated annealing algorithm to optimize the dwell times at preselected dwell positions to maximize tumor coverage under dose-volume constraints on the organs at risk. Compared to existing algorithms, our algorithm has advantages in terms of speed and objective value and does not require an expensive general purpose solver. Its success mainly depends on exploiting the efficiency of matrix multiplication and a careful selection of the neighboring states. In this paper we outline its details and make an in-depth comparison with existing methods using real patient data. PMID:26760757

  10. High-dose-rate interstitial brachytherapy for the treatment of penile carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Petera, J.; Odrazka, K.; Zouhar, M.; Bedrosova, J.; Dolezel, M. [Dept. of Oncology and Radiotherapy, Charles Univ. Medical School and Teaching Hospital, Hradec Kralove (Czech Republic)

    2004-02-01

    Background: interstitial low-dose-rate (LDR) brachytherapy allows conservative treatment of T1-T2 penile carcinoma. High-dose-rate (HDR) is often considered to be dangerous for interstitial implants because of a higher risk of complications, but numerous reports suggest that results may be comparable to LDR. Nevertheless, there are no data in the literature available regarding HDR interstitial brachytherapy for carcinoma of the penis. Case report: a 64-year-old man with T1 NO MO epidermoid carcinoma of the glans is reported. Interstitial HDR brachytherapy was performed using the stainless hollow needle technique and a breast template for fixation and good geometry. The dose delivered was 18 x 3 Gy twice daily. Results: after 232 days from brachytherapy, the patient was without any evidence of the tumor, experienced no serious radiation-induced complications, and had a fully functional organ. Conclusion: HDR interstitial brachytherapy is feasible in selected case of penis carcinoma, when careful planning and small single fractions are used. (orig.)

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

    International Nuclear Information System (INIS)

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

  12. Adherence to Vaginal Dilation Following High Dose Rate Brachytherapy for Endometrial Cancer

    International Nuclear Information System (INIS)

    Purpose: We report demographic, clinical, and psychosocial factors associated with adherence to vaginal dilation and describe the sexual and marital or nonmarital dyadic functioning of women following high dose rate (HDR) brachytherapy for endometrial cancer. Methods and Materials: We retrospectively evaluated women aged 18 years or older in whom early-stage endometrial (IAgr3-IIB) cancers were treated by HDR intravaginal brachytherapy within the past 3.5 years. Women with or without a sexual partner were eligible. Patients completed questionnaires by mail or by telephone assessing demographic and clinical variables, adherence to vaginal dilation, dyadic satisfaction, sexual functioning, and health beliefs. Results: Seventy-eight of 89 (88%) eligible women with early-stage endometrial cancer treated with HDR brachytherapy completed questionnaires. Only 33% of patients were adherers, based on reporting having used a dilator more than two times per week in the first month following radiation. Nonadherers who reported a perceived change in vaginal dimension following radiation reported that their vaginas were subjectively smaller after brachytherapy (p = 0.013). Adherers reported more worry about their sex lives or lack thereof than nonadherers (p = 0.047). Patients reported considerable sexual dysfunction following completion of HDR brachytherapy. Conclusions: Adherence to recommendations for vaginal dilator use following HDR brachytherapy for endometrial cancer is poor. Interventions designed to educate women about dilator use benefit may increase adherence. Although sexual functioning was compromised, it is likely that this existed before having cancer for many women in our study.

  13. Curative high dose rate vaginal apex brachytherapy in stage I papillary serous carcinoma of the endometrium

    International Nuclear Information System (INIS)

    Introduction: Uterine papillary serous carcinoma (UPSC) is a morphologically distinct variant of endometrial carcinoma that is associated with a poor prognosis, high recurrence rate, clinical understaging, and poor response to salvage treatment. We describe the presentation, local and distant control, survival, salvage rate, and complications for patients undergoing whole abdominal radiation therapy (WART), low dose rate (LDR) intracavitary brachytherapy, or high dose rate (HDR) vaginal brachytherapy in patients with stage I UPSC. Methods: Between 1976 and 1994 more than 1700 patients with endometrial carcinoma were treated with radiation therapy, 30 patients with stage I UPSC (1.8%) were treated with radiation before or following TAH/BSO. All patients underwent either preoperative Simon's packing or tandem and plaque which delivered 30-40 Gy to the serosa, WART, or HDR Ir-192 vaginal apex brachytherapy to a total dose of 21 Gy in 3 fractions at 0.5 cm from the vaginal mucosa. A total of 14 patients received HDR vaginal brachytherapy and (5(14)) patients received systemic chemotherapy. All patients presented with vaginal bleeding at a median age of 67 years (range 34-88). The group of 30 patients underwent TAH/BSO, 17 patients were completely staged pathologically (pelvic and para-aortic lymph nodes, omentectomy, and pelvic washings), and 2 patients underwent omental biopsy and pelvic washings only. All specimens revealed UPSC, nuclear grade 3, and lymphovascular invasion (23%). The pathologic stage was IA: 23% (7), IB: 67% (20), and IC: 10% (3). The median follow-up for all patients was 49 months (range 13-187 months). For the patients receiving postoperative HDR vaginal brachytherapy the median time from surgery to radiation was 42 days (range 29-91). Results: The 5-year actuarial disease free survival for Figo stage I UPSC patients treated with postoperative HDR vaginal brachytherapy and systemic chemotherapy was 100% compared to 74% for stage I UPSC patient

  14. The emerging role of high-dose-rate (HDR) brachytherapy as monotherapy for prostate cancer

    International Nuclear Information System (INIS)

    High-dose-rate (HDR) brachytherapy as monotherapy is a comparatively new brachytherapy procedure for prostate cancer. In addition to the intrinsic advantages of brachytherapy, including radiation dose concentration to the tumor and rapid dose fall-off at the surrounding normal tissue, HDR brachytherapy can yield a more homogeneous and conformal dose distribution through image-based decisions for source dwell positions and by optimization of individual source dwell times. Indication can be extended even to T3a/b or a part of T4 tumors because the applicators can be positioned at the extracapsular lesion, into the seminal vesicles, and/or into the bladder, without any risk of source migration or dropping out. Unlike external beam radiotherapy, with HDR brachytherapy inter-/intra-fraction organ motion is not problematic. However, HDR monotherapy requires patients to stay in bed for 1-4 days during hospitalization, even though the actual overall treatment time is short. Recent findings that the α/β value for prostate cancer is less than that for the surrounding late-responding normal tissue has made hypofractionation attractive, and HDR monotherapy can maximize this advantage of hypofractionation. Research on HDR monotherapy is accelerating, with a growing number of publications reporting excellent preliminary clinical results due to the high 'biologically effective dose (BED)' of >200 Gy. Moreover, the findings obtained for HDR monotherapy as an early model of extreme hypofractionation tend to be applied to other radiotherapy techniques such as stereotactic radiotherapy. All these developments point to the emerging role of HDR brachytherapy as monotherapy for prostate cancer. (author)

  15. Interstitial high-dose rate brachytherapy as boost for anal canal cancer

    International Nuclear Information System (INIS)

    To assess clinical outcomes of patients treated with a high-dose rate brachytherapy boost for anal canal cancer (ACC). From August 2005 to February 2013, 28 patients presenting an ACC treated by split-course external beam radiotherapy (EBRT) and HDR brachytherapy with or without chemotherapy in a French regional cancer center in Nice were retrospectively analyzed. Median age was 60.6 years [34 – 83], 25 patients presented a squamous cell carcinoma and 3 an adenocarcinoma; 21 received chemotherapy. Median dose of EBRT was 45 Gy [43.2 – 52]. Median dose of HDR brachytherapy was 12 Gy [10 - 15] with a median duration of 2 days. Median overall treatment time was 63 days and median delay between EBRT and brachytherapy was 20 days. Two-year local relapse free, metastatic free, disease free and overall survivals were 83%, 81.9%, 71.8% and 87.7% respectively. Acute toxicities were frequent but not severe with mostly grade 1 toxicities: 37% of genito-urinary, 40.7% of gastro-intestinal and 3.7% of cutaneous toxicities. Late toxicities were mainly G1 (43.1%) and G2 (22%). Two-year colostomy-free survival was 75.1%, one patient had a definitive sphincter amputation. High-dose rate brachytherapy for anal canal carcinoma as boost represents a feasible technique compared to low or pulsed-dose rate brachytherapy. This technique remains an excellent approach to precisely boost the tumor in reducing the overall treatment time

  16. Use of Monte Carlo Methods in brachytherapy

    International Nuclear Information System (INIS)

    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)

  17. The usefulness of metal markers for CTV-based dose prescription in high-dose-rate interstitial brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Ken; Mitomo, Masanori [Osaka National Hospital (Japan); Nose, Takayuki; Koizumi, Masahiko; Nishiyama, Kinji [Osaka Prefectural Center for Adult Diseases (Japan); Yoshida, Mineo [Sanda City Hospital, Hyogo (Japan)

    2002-12-01

    We employ a clinical target volume (CTV)-based dose prescription for high-dose-rate (HDR) interstitial brachytherapy. However, it is not easy to define CTV and organs at risk (OAR) from X-ray film or CT scanning. To solve this problem, we have utilized metal markers since October 1999. Moreover, metal markers can help modify dose prescription. By regulating the doses to the metal markers, refining the dose prescription can easily be achieved. In this research, we investigated the usefulness of the metal markers. Between October 1999 and May 2001, 51 patients were implanted with metal markers at Osaka Medical Center for Cancer and Cardiovascular Diseases (OMCC), Osaka National Hospital (ONH) and Sanda City Hospital (SCH). Forty-nine patients (head and neck: 32; pelvis: 11; soft tissue: 3; breast: 3) using metal markers were analyzed. During operation, we implanted 179 metal markers (49 patients) to CTV and 151 markers (26 patients) to OAR. At treatment planning, CTV was reconstructed judging from the metal markers, applicator position and operation records. Generally, we prescribed the tumoricidal dose to an isodose surface that covers CTV. We also planned to limit the doses to OAR lower than certain levels. The maximum normal tissue doses were decided 80%, 150%, 100%, 50% and 200% of the prescribed doses for the rectum, the urethra, the mandible, the skin and the large vessel, respectively. The doses to the metal markers using CTV-based dose prescription were generated. These were compared with the doses theoretically calculated with the Paris system. Treatment results were also investigated. The doses to the 158 metal markers (42 patients) for CTV were higher than ''tumoricidal dose''. In 7 patients, as a result of compromised dose prescription, 9 markers were lower than the tumoricidal dose. The other 12 markers (7%) were excluded from dose evaluation because they were judged as miss-implanted. The doses to the 142 metal markers (24 patients

  18. High dose rate prostate brachytherapy: an overview of the rationale, experience and emerging applications in the treatment of prostate cancer

    OpenAIRE

    Challapalli, A; Jones, E; C Harvey; Hellawell, G O; Mangar, S A

    2012-01-01

    The technological advances in real-time ultrasound image guidance for high dose rate (HDR) prostate brachytherapy places this treatment modality at the forefront of innovation in radiotherapy. This review article will explore the rationale for HDR brachytherapy as a highly conformal method of dose delivery and safe dose escalation to the prostate, in addition to the particular radiobiological advantages it has over low dose rate and external beam radiotherapy. The encouraging outcome data and...

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

    International Nuclear Information System (INIS)

    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

  20. Treatment of keloids by high-dose-rate brachytherapy: A seven-year study

    International Nuclear Information System (INIS)

    Purpose: To analyze the results obtained in a prospective group of patients with keloid scars treated by high-dose-rate (HDR) brachytherapy with or without surgery. Methods and Materials: One hundred and sixty-nine patients with keloid scars were treated with HDR brachytherapy between December 1991 and December 1998. One hundred and thirty-four patients were females, and 35 were males. The distribution of keloid scars was as follows: face, 77; trunk, 73; and extremities, 19. The mean length was 4.2 cm (range 2-22 cm), and the mean width 1.8 cm (range 1.0-2.8 cm). In 147 patients keloid tissues were removed before HDR brachytherapy treatment, and in 22 HDR brachytherapy was used as definitive treatment. In patients who underwent prior surgery, a flexible plastic tube was put in place during the surgical procedure. Bottoms were used to fix the plastic tubes, and the surgical wound was repaired by absorbable suture. HDR brachytherapy was administered within 30-60 min of surgery. A total dose of 12 Gy (at 1 cm from the center of the catheter) was given in four fractions of 300 cGy in 24 h (at 09.00 am, 15.00 pm, 21.00 pm, and 09.00 am next day). Treatment was optimized using standard geometric optimization. In patients who did not undergo surgery, standard brachytherapy was performed, and plastic tubes were placed through the skin to cover the whole scar. Local anesthesia was used in all procedures. In these patients a total dose of 18 Gy was given in 6 fractions of 300 cGy in one and a half days (at 9.00 am, 3.00 pm, and 9.00 pm; and at 9.00 am, 3.00 pm, and 9.00 pm next day). No further treatment was given to any patient. Patients were seen in follow-up visits every 3 months during the first year, every 6 months in the second year, and yearly thereafter. No patient was lost to follow-up. Particular attention was paid to keloid recurrence, late skin effects, and cosmetic results. Results: All patients completed the treatment. After a follow-up of seven years, 8

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

    International Nuclear Information System (INIS)

    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)

  2. Dose metrology for high dose rate brachytherapy: from the definition of the national standard towards transfer to users

    International Nuclear Information System (INIS)

    The Laboratoire National Henri Becquerel (LNE-LNHB) has developed a national standard for high dose rate brachytherapy. This document describes the complete procedure from the definition of the national standard down to the transfer to users. A perspective for future work is also presented. (authors)

  3. Interaction of 2-Gy Equivalent Dose and Margin Status in Perioperative High-Dose-Rate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To determine patient, tumor, and treatment factors predictive of local control (LC) in a series of patients treated with either perioperative high-dose-rate brachytherapy (PHDRB) alone (Group 1) or with PHDRB combined with external-beam radiotherapy (EBRT) (Group 2). Patient and Methods: Patients (n = 312) enrolled in several PHDRB prospective Phase I-II studies conducted at the Clinica Universidad de Navarra were analyzed. Treatment with PHDRB alone, mainly because of prior irradiation, was used in 126 patients to total doses of 32 Gy/8 b.i.d. or 40 Gy/10 b.i.d. treatments after R0 or R1 resections. Treatment with PHDRB plus EBRT was used in 186 patients to total doses of 16 Gy/4 b.i.d. or 24 Gy/6 b.i.d. treatments after R0 or R1 resections along with 45 Gy of EBRT with or without concomitant chemotherapy. Results: No dose-margin interaction was observed in Group 1 patients. In Group 2 patients there was a significant interaction between margin status and 2-Gy equivalent (Eq2Gy) dose (p = 0.002): (1) patients with negative margins had 9-year LC of 95.7% at Eq2Gy = 62.9Gy; (2) patients with close margins of >1 mm had 9-year LC of 92.4% at Eq2Gy = 72.2Gy, and (3) patients with positive/close <1-mm margins had 9-year LC of 68.0% at Eq2Gy = 72.2Gy. Conclusions: Two-gray equivalent doses ≥70 Gy may compensate the effect of close margins ≥1 mm but do not counterbalance the detrimental effect of unfavorable (positive/close <1 mm) resection margins. No dose-margin interaction is observed in patients treated at lower Eq2Gy doses ≤50 Gy with PHDRB alone.

  4. Construction of a anthropomorphic phantom for dose measurement in hands in brachytherapy procedures

    International Nuclear Information System (INIS)

    The main objective of this work was to show the differences between the dose value measured by dosimeter endpoint and the values measured in different points inside the hand during brachytherapy procedures. For this, the procedures involved in the handling of sources were analyzed and the simulated using an anthropomorphic phantom hand

  5. Staff dose of hospitalization in the treatment of patients in ophthalmic brachytherapy with 125 I

    International Nuclear Information System (INIS)

    The objective of this work, therefore, has been the evaluation of the dose levels which nursing staff can receive in care for ophthalmic brachytherapy patients treated with 125 I from measurements made on the same, evaluating, in an experimental way, job security following the PR rules laid down for these treatments. (Author)

  6. Surface membrane based bladder registration for evaluation of accumulated dose during brachytherapy in cervical cancer

    DEFF Research Database (Denmark)

    Noe, Karsten Østergaard; Tanderup, Kari; Sørensen, Thomas Sangild

    2011-01-01

    of the fixed surface. Optional landmark based matches can be included in the suggested iterative solver. The technique is demonstrated for bladder registration in brachytherapy treatment evaluation of cervical cancer. It holds promise to better estimate the accumulated but unintentional dose delivered...

  7. Doses of radiation in the environment of patients undergoing treatment of ophthalmic brachytherapy

    International Nuclear Information System (INIS)

    This paper presents results for measures of dose made to different patient undergoing treatment with ophthalmic brachytherapy. The aim of these measures has been, on the one hand, verify assessments relating to radiation protection in the memory of the installation and, on the other hand, experimental measures that can serve to reduce the perception of the radiological risk professionals have. (Author)

  8. Application of a color scanner for 60Co high dose rate brachytherapy dosimetry with EBT radiochromic film

    International Nuclear Information System (INIS)

    The aim of this study is to evaluate the performance of a color scanner as a radiochromic film reader in two dimensional dosimetry around a high dose rate brachytherapy source. A Microtek ScanMaker 1000XL film scanner was utilized for the measurement of dose distribution around a high dose rate GZP6 60Co brachytherapy source with GafChromic® EBT radiochromic films. In these investigations, the non-uniformity of the film and scanner response, combined, as well as the films sensitivity to scanner’s light source was evaluated using multiple samples of films, prior to the source dosimetry. The results of these measurements were compared with the Monte Carlo simulated data using MCNPX code. In addition, isodose curves acquired by radiochromic films and Monte Carlo simulation were compared with those provided by the GZP6 treatment planning system. Scanning of samples of uniformly irradiated films demonstrated approximately 2.85% and 4.97% nonuniformity of the response, respectively in the longitudinal and transverse directions of the film. Our findings have also indicated that the film response is not affected by the exposure to the scanner’s light source, particularly in multiple scanning of film. The results of radiochromic film measurements are in good agreement with the Monte Carlo calculations (4%) and the corresponding dose values presented by the GZP6 treatment planning system (5%). The results of these investigations indicate that the Microtek ScanMaker 1000XL color scanner in conjunction with GafChromic EBT film is a reliable system for dosimetric evaluation of a high dose rate brachytherapy source

  9. A brachytherapy treatment planning system based on dicom images and MCNP5 calculations optimized with artificial neural network

    International Nuclear Information System (INIS)

    Exact dose calculation is an important part of brachytherapy Treatment Planning Systems (TPS). Currently used methods, such as analytic methods or tabulated data are inexact, as they are based on dose calculation in homogeneous water medium. Dose calculation systems such as CT based Monte Carlo simulation are the most exact, but they take too much time to reach the desirable accuracy. The aim of this research is to optimize the CT-based Monte Carlo dose calculation for dynamic Treatment Planning systems by using an Artificial Neural Network (ANN) which is capable of calculating the dose distribution with the same accuracy as the CT based Monte Carlo simulation. 80000 Dose distributions -produced by the Best no.2301 seed source in different positions in the CT scan of the prostate- was calculated by the Monte Carlo Neutral particle (MCNP)5 code and this data was used to train the ANN. The ANN was tested for 26768 cases which were not used for the training step, with an average error of 0.8 percent compared to MCNP5 results. (author)

  10. Clinical results of iridium-192 high dose rate brachytherapy with external beam radiotherapy

    International Nuclear Information System (INIS)

    Here, we report the clinical results of iridium-192 high dose rate brachytherapy at Kanazawa University Hospital. The study population consisted of 166 patients diagnosed with T1c-T3bN0M0 prostate cancer treated with high dose rate brachytherapy and external beam radiotherapy and followed up for 6 months or longer. Treatment consisted of external beam radiotherapy to the prostate at 44 Gy/22 fractions and high dose rate brachytherapy at 18 Gy/3 fractions. Median follow-up interval was 31.5 months (range 6.2-88.7). The overall 5-year biological recurrence-free survival rate was 93.0%. The 5-year biological recurrence-free survival rates for the patients in low-, intermediate- and high-risk groups according to the D'Amico risk classification criteria were 96.1%, 89.0% and 91.6%, respectively. When limited to the group that did not receive adjuvant hormonal therapy, the 5-year biological recurrence-free survival rates for the patients in low-, intermediate- and high-risk groups were 96.0%, 96.3% and 82.9%, respectively. Grade 3 or greater adverse effects were rare. Urethral stricture was observed in only 1.0% of the patients. Eighty percent of patients retained erectile function after high dose rate brachytherapy and reported satisfaction with sexual function. High dose rate brachytherapy is considered a good form of treatment for localized prostate cancer, although longer follow-up is necessary. (author)

  11. High dose rate endovascular brachytherapy in aorto-iliac lesion for the prevention of restenosis

    International Nuclear Information System (INIS)

    This study examined the applicability of endovascular brachytherapy to larger del arteries such as the abdominal aorta and iliac artery. Endovascular brachytherapy using an Ir-192 HDR source was administered 11 times to nine patients who had undergone percutaneous transluminal angioplasty (PTA) between 1995 and 1999. The follow-up lasted 13 to 55 months after treatment (median, 24 months). Eight of the 11 lesions have been controlled so far. Although one case developed thrombus inside the stent five months later, recanalization was achieved by means of retreatment. One patient who underwent low-dose irradiation (6 Gy) without stent implantation showed restenosis five months after treatment. We used a centering catheter that did not block the blood stream for exact centering of the radiation source in larger vessels such as the abdominal aorta. Although endovascular brachytherapy is a promising and safe procedure, careful follow-up is needed to detect untoward reactions such as thrombosis. (author)

  12. High dose rate endovascular brachytherapy in aorto-iliac lesion for the prevention of restenosis

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Hideya [Toyonaka Municipal Hospital, Osaka (Japan); Tomoda, Kaname; Shiomi, Hiroya [Osaka Univ., Suita (Japan). Graduate School of Medicine] [and others

    2002-02-01

    This study examined the applicability of endovascular brachytherapy to larger del arteries such as the abdominal aorta and iliac artery. Endovascular brachytherapy using an Ir-192 HDR source was administered 11 times to nine patients who had undergone percutaneous transluminal angioplasty (PTA) between 1995 and 1999. The follow-up lasted 13 to 55 months after treatment (median, 24 months). Eight of the 11 lesions have been controlled so far. Although one case developed thrombus inside the stent five months later, recanalization was achieved by means of retreatment. One patient who underwent low-dose irradiation (6 Gy) without stent implantation showed restenosis five months after treatment. We used a centering catheter that did not block the blood stream for exact centering of the radiation source in larger vessels such as the abdominal aorta. Although endovascular brachytherapy is a promising and safe procedure, careful follow-up is needed to detect untoward reactions such as thrombosis. (author)

  13. Prenatal radiation exposure. Dose calculation

    International Nuclear Information System (INIS)

    The unborn child requires special protection. In this context, the indication for an X-ray examination is to be checked critically. If thereupon radiation of the lower abdomen including the uterus cannot be avoided, the examination should be postponed until the end of pregnancy or alternative examination techniques should be considered. Under certain circumstances, either accidental or in unavoidable cases after a thorough risk assessment, radiation exposure of the unborn may take place. In some of these cases an expert radiation hygiene consultation may be required. This consultation should comprise the expected risks for the unborn while not perturbing the mother or the involved medical staff. For the risk assessment in case of an in-utero X-ray exposition deterministic damages with a defined threshold dose are distinguished from stochastic damages without a definable threshold dose. The occurrence of deterministic damages depends on the dose and the developmental stage of the unborn at the time of radiation. To calculate the risks of an in-utero radiation exposure a three-stage concept is commonly applied. Depending on the amount of radiation, the radiation dose is either estimated, roughly calculated using standard tables or, in critical cases, accurately calculated based on the individual event. The complexity of the calculation thereby increases from stage to stage. An estimation based on stage one is easily feasible whereas calculations based on stages two and especially three are more complex and often necessitate execution by specialists. This article demonstrates in detail the risks for the unborn child pertaining to its developmental phase and explains the three-stage concept as an evaluation scheme. It should be noted, that all risk estimations are subject to considerable uncertainties.

  14. A comparison of organs at risk doses in GYN intracavitary brachytherapy for different tandem lengths and bladder volumes.

    Science.gov (United States)

    Siavashpour, Zahra; Aghamiri, Mahmoud Reza; Jaberi, Ramin; ZareAkha, Naser; Dehghan Manshadi, Hamid Reza; Kirisits, Christian; Sedaghat, Mahbod

    2016-01-01

    The purpose of this study was to investigate the concurrent effects of tandem length and bladder volume on dose to pelvic organs at risk (OARs) in HDR intracavitary brachytherapy treatment of cervical cancer. Twenty patients with locally advanced cervical cancer were selected for brachytherapy using Rotterdam applicators. The patients were CT scanned twice with empty and full bladder. Two treatment plans were prepared on each of the image sets. Patients were categorized into two groups; those treated with a tandem length of 4 cm or smaller (T ≤ 4 cm) and those with tandem length larger than 4 cm (T > 4 cm). Only one tandem tip angle of 30° was studied. Dose-volume histograms (DVHs) of OARs were calculated and compared. Bladder dose was significantly affected by both bladder volume and tandem physical length for T ≤ 4 cm. This was reflected on the values obtained for D2cm³, D1cm³, and D0.1cm³ for both empty and full bladder cases. When T > 4 cm, no correlation could be established between variations in bladder dose and blad-der volume. Rectum dose was generally lower when the bladder was empty and T > 4 cm. Dose to sigmoid was increased when T > 4 cm; this increase was larger when the bladder was full. Our results suggest that, for tandems longer than 4 cm, keeping the bladder empty may reduce the dose to rectum and sigmoid. This is contrary to cases where a shorter than 4 cm tandem is used in which a full bladder (about 50-120 cm³) tends to result in a lower dose to rectum and sigmoid. Attention should be given to doses to sigmoid with long tandem lengths, as a larger tandem generally results in a larger dose to sigmoid. PMID:27167253

  15. The mechanical system design of the iridium-192 isotope wire in cervical cancer brachytherapy with medium dose rate

    International Nuclear Information System (INIS)

    In 2010, brachytherapy engineering activities have a purpose to establish a detailed design of the cervical cancer brachytherapy with medium dose rate. The brachytherapy will use an Iridium-92 source with the emiting radiation of 5 to 10 Curies. The source is wrapped in SS-316 capsule and carried by a SS-316 wire having diameter of about 1 mm dan length of 1800 mm. As part of this activity, the preliminary design of the mechanical drive systems for the isotope source has been developed. The technical specifications for the main components of the mechanical drive system have been successfully determined. This is started by studying the concept design, performing calculations, determining technical specifications, and finally defining the main components. From the evaluation, some components were decided: a stepper motor PK264A1-SG10, needle bearing NKI-10/20, spiral tube in SS316-1/8'' with 120 mm in diameter, rubber-based belts with a width of 20 mm, and aluminium drum with a diameter of 100 mm. Not all components could be identified in detail, especially for the components that do not exist in the market place and have to be created ourself. Since the main components have been identified, the detailed design step of the mechanical drive systems for the isotope source can be performed. (author)

  16. Preparation of a program for the independent verification of the brachytherapy planning systems calculations; Confeccion de un programa para la verificacion independiente de los calculos de los sistemas de planificacion en braquiterapia

    Energy Technology Data Exchange (ETDEWEB)

    V Carmona, V.; Perez-Calatayud, J.; Lliso, F.; Richart Sancho, J.; Ballester, F.; Pujades-Claumarchirant, M.C.; Munoz, M.

    2010-07-01

    In this work a program is presented that independently checks for each patient the treatment planning system calculations in low dose rate, high dose rate and pulsed dose rate brachytherapy. The treatment planning system output text files are automatically loaded in this program in order to get the source coordinates, the desired calculation point coordinates and the dwell times when it is the case. The source strength and the reference dates are introduced by the user. The program allows implementing the recommendations about independent verification of the clinical brachytherapy dosimetry in a simple and accurate way, in few minutes. (Author).

  17. Intraluminal High-Dose-Rate Brachytherapy for the Tumors of Gastrointestinal Tract

    International Nuclear Information System (INIS)

    Purpose : Intraluminal High dose rate brachytherapy is an accepted treatment for the tumors of GI tract. However, there is only some limited clinical data for intraluminal high dose rate brachytherapy for the tumors of GI tract. Materials and Methods : Between February 1991 and July 1993, 18 patients who have the tumors of GI tract (esophageal cancer-8 cases, rectal cancer-10 cases) were treated with high dose rae iridium-192 afterloading system )Microselectron-HDR, Nucletron CO, Netherland) at the department of therapeutic radiology, St. Mary's hospital, Catholic university medical college. Age rage was 47-87 years with a mean age 71 years. All patients were treated with intraluminal high dose rate brachytherapy within two weeks after conventional external radiation therapy and received 3-5 Gy/fraction 3-4 times per week to a total dose 12-20 Gy (mean 17 Gy). Standard fractionation and conventional dose were delivered for external radiation therapy. Total dose of external radiation therapy ranged 41.4-59.4 Gy (mean 49.6 Gy). Median follow up was 19 months. Results : The analysis was based on 18 patients. The complete response and partial response in esophageal cancer was similar (38%). Two year rates for survival and median survival were 13% and 10 months, respectively. Among 10 patients of rectal cancers, partial response was obtained in 6 patients (60%). There was no complete response in the patients with rectal cancer, but good palliative results were achieved in all patients. Conclusion : Although the number of patients was not large and the follow up period was relatively short, these findings suggested that intraluminal high dose rate brachytherapy could be useful in the treatment of the patients with advanced tumors of GI tract

  18. Salvage high-dose-rate interstitial brachytherapy for locally recurrent rectal cancer*

    Science.gov (United States)

    Pellizzon, Antônio Cássio Assis

    2016-01-01

    For tumors of the lower third of the rectum, the only safe surgical procedure is abdominal-perineal resection. High-dose-rate interstitial brachytherapy is a promising treatment for local recurrence of previously irradiated lower rectal cancer, due to the extremely high concentrated dose delivered to the tumor and the sparing of normal tissue, when compared with a course of external beam radiation therapy.

  19. Evaluation of functioning of high dose rate brachytherapy at the Instituto Nacional do Cancer

    International Nuclear Information System (INIS)

    Quality control tests are very useful tools to assure the quality of patient's treatment. A daily control of the high dose rate micro selectron was performed based on the security parameters of the equipment and on the quickness of performance. The purpose of this report is to evaluate and to discuss the errors found during the first three years with the high dose rate brachytherapy, at the Instituto Nacional de Cancer. (author)

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

    International Nuclear Information System (INIS)

    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

  1. Routine clinical estimation of rectal, rectosigmoidal, and bladder doses from intracavitary brachytherapy in the treatment of carcinoma of the cervix

    International Nuclear Information System (INIS)

    An evaluation of rectal, rectosigmoidal, and bladder doses from intracavitary brachytherapy in carcinoma of the cervix has been initiated on a routine basis in an effort to obtain the optimum radiotherapeutic dose. Contrast radiography on a radiotherapy simulator is used to image the rectum and bladder, and dose rates are determined at predesignated reference points with the aid of computer calculated dose distributions. Forty-three patients have been reviewed in order to ascertain the correlation between radiation injury and dose at reference points in the rectum and bladder. In a related study involving 77 patients, the doses at points A and B and the prescription in mghr were analyzed in relation to radiation injury. There was no apparent association between the incidence of radiation injury in either the mghr prescription or the doses at points A or B. Computer calculations were supplemented with in vivo and in vitro thermoluminescent dosimeter (TLD) measurements. We conclude that routine contrast radiography of the rectum and the bladder with dose calculations at selected reference points provides important information for optimizing radiotherapy in carcinoma of the cervix without a significant increase in treatment planning effort or patient discomfort

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

    International Nuclear Information System (INIS)

    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

  3. In vivo dosimetry using electron paramagnetic resonance in L-alanine in gynecological low dose rate brachytherapy

    International Nuclear Information System (INIS)

    To present the results of in vivo dosimetry performed on 15 patients treated for gynecological cancer with the aim of optimizing the detector design and its application in body cavities and comparing the doses measured in vivo with those calculated by the Plato (Nucletron) system of brachytherapy treatment planning. Electron paramagnetic resonance (EPR) is, as a dosimetric method, based on the detection of free radicals generated by ionizing radiation in L-alanine. The concentration of free radicals is proportional to the absorbed dose and is determined by the EPR technique. The detectors appear as small cellulose capsules (outer diameter 5 mm, length 15 mm), tightly filled with crystalline L-alanine powder. The doses from 137Cs brachytherapy sources were measured in selected points inside the rectum and vagina. The relative deviations of measured doses from those calculated by the treatment planning system ranged from -28% to +40%. The mean deviations from the prescribed doses were relatively low (+1% for detectors placed in the rectum, - 10% for detectors placed in the vagina). However, due to a low number of samples and large standard deviations of the mean values (±23% and ±11% for detectors placed in the rectum and the vagina, respectively), the deviations of the mean values are of low statistical significance. The accuracy of the measurements was analyzed and is hereby discussed. The main sources of the differences between the measured and calculated dose should, generally, be attributed to uncertainties in the determination of the detector position inside the body as ascertained from the radiographs and to uncontrollable motion of detectors during treatment. (author)

  4. Correlation of Point B and Lymph Node Dose in 3D-Planned High-Dose-Rate Cervical Cancer Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To compare high dose rate (HDR) point B to pelvic lymph node dose using three-dimensional-planned brachytherapy for cervical cancer. Methods and Materials: Patients with FIGO Stage IB-IIIB cervical cancer received 70 tandem HDR applications using CT-based treatment planning. The obturator, external, and internal iliac lymph nodes (LN) were contoured. Per fraction (PF) and combined fraction (CF) right (R), left (L), and bilateral (Bil) nodal doses were analyzed. Point B dose was compared with LN dose-volume histogram (DVH) parameters by paired t test and Pearson correlation coefficients. Results: Mean PF and CF doses to point B were R 1.40 Gy ± 0.14 (CF: 7 Gy), L 1.43 ± 0.15 (CF: 7.15 Gy), and Bil 1.41 ± 0.15 (CF: 7.05 Gy). The correlation coefficients between point B and the D100, D90, D50, D2cc, D1cc, and D0.1cc LN were all less than 0.7. Only the D2cc to the obturator and the D0.1cc to the external iliac nodes were not significantly different from the point B dose. Significant differences between R and L nodal DVHs were seen, likely related to tandem deviation from irregular tumor anatomy. Conclusions: With HDR brachytherapy for cervical cancer, per fraction nodal dose approximates a dose equivalent to teletherapy. Point B is a poor surrogate for dose to specific nodal groups. Three-dimensional defined nodal contours during brachytherapy provide a more accurate reflection of delivered dose and should be part of comprehensive planning of the total dose to the pelvic nodes, particularly when there is evidence of pathologic involvement.

  5. Current situation of high-dose-rate brachytherapy for cervical cancer in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Rogerio Matias Vidal da; Souza, Divanizia do Nascimento, E-mail: rmv.fisica@gmail.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil); Pinezi, Juliana Castro Dourado [Pontificia Universidade Catolica de Goias (PUC-Goias), Goiania, GO (Brazil); Macedo, Luiz Eduardo Andrade [Hospital Chama, Arapiraca, AL (Brazil)

    2014-05-15

    To assess the current situation of high-dose-rate (HDR) brachytherapy for cancer of the cervix in Brazil, regarding apparatuses, planning methods, prescription, fractionation schedule and evaluation of dose in organs at risk. Materials and methods: in the period between March/2012 and May/2013, a multiple choice questionnaire was developed and sent to 89 Brazilian hospitals which perform HDR brachytherapy. Results: sixty-one services answered the questionnaire. All regions of the country experienced a sharp increase in the number of HDR brachytherapy services in the period from 2001 to 2013. As regards planning, although a three-dimensional planning software was available in 91% of the centers, conventional radiography was mentioned by 92% of the respondents as their routine imaging method for such a purpose. Approximately 35% of respondents said that brachytherapy sessions are performed after teletherapy. The scheme of four 7 Gy intracavitary insertions was mentioned as the most frequently practiced. Conclusion: the authors observed that professionals have difficulty accessing adjuvant three-dimensional planning tools such as computed tomography and magnetic resonance imaging. (author)

  6. Current situation of high-dose-rate brachytherapy for cervical cancer in Brazil

    International Nuclear Information System (INIS)

    To assess the current situation of high-dose-rate (HDR) brachytherapy for cancer of the cervix in Brazil, regarding apparatuses, planning methods, prescription, fractionation schedule and evaluation of dose in organs at risk. Materials and methods: in the period between March/2012 and May/2013, a multiple choice questionnaire was developed and sent to 89 Brazilian hospitals which perform HDR brachytherapy. Results: sixty-one services answered the questionnaire. All regions of the country experienced a sharp increase in the number of HDR brachytherapy services in the period from 2001 to 2013. As regards planning, although a three-dimensional planning software was available in 91% of the centers, conventional radiography was mentioned by 92% of the respondents as their routine imaging method for such a purpose. Approximately 35% of respondents said that brachytherapy sessions are performed after teletherapy. The scheme of four 7 Gy intracavitary insertions was mentioned as the most frequently practiced. Conclusion: the authors observed that professionals have difficulty accessing adjuvant three-dimensional planning tools such as computed tomography and magnetic resonance imaging. (author)

  7. Pulsed-dose-rate brachytherapy: design of convenient (daytime-only) schedules

    International Nuclear Information System (INIS)

    Purpose: To design pulsed-brachytherapy (PDR) protocols that are expected to be at least as clinically efficacious (in terms of both tumor control and late sequelae) as continuous low-dose-rate (CLDR) regimens, but that involve irradiation only during extended office hours. Both interstitial and intracavitary brachytherapy protocols are considered. Methods and Materials: The linear quadratic formalism was used in which the late normal tissue damage and tumor control for one protocol relative to another are assumed to be determined primarily by the level of cellular survival. PDR schedules were designed in which pulses are delivered during 'extended office hours' (8 A.M. to 8 P.M.) with no irradiation overnight. Generally, the proposed PDR regimes last the same number of treatment days as the corresponding CLDR regimen, but the PDR treatment lasts longer on the final day (i.e., until 8 P.M.). PDR doses were calculated such as to produce a tumor control which is equivalent to standard CLDR protocols, and the corresponding predicted late complication rate was compared with that for CLDR. Ranges of plausible values for the half-times of sublethal damage repair for tumors and for late-responding normal tissues were considered. Results: As has been previously shown, the efficacy of PDR relative to CLDR depends considerably on the repair rates for sublethal damage repair. Clinical and experimental evidence suggests that average repair half-times for early effects (e.g., tumor control) are less than about a half hour, and for late sequelae are more than about an hour. If these estimates are correct, daytime PDR regimes can usually be designed which take the same number of days as the corresponding CLDR regimen, but have comparable or better therapeutic ratios than CLDR. Conclusion: Protocols for PDR can be designed to involve irradiation only during extended office hours, that are likely to result in clinical results comparable or better than CLDR, for any expected

  8. Interstitial high dose rate brachytherapy for cancer of the oral tongue

    International Nuclear Information System (INIS)

    Between October 1992 and March 1996, 34 patients with cancer of the tongue without nodal metastases underwent fractionated interstitial brachytherapy with a high dose rate (HDR) iridium remote afterloader. The types of treatment consisted of brachytherapy (BT) alone: 8 cases, BT after surgery: 3 cases, BT after systemic chemotherapy: 3 cases, BT after arterial infusion (AI): 14 cases, BT after external beam radiotherapy (ERT): 5 cases, and BT after AI+ERT: 1 case. Applicators were implanted under general anesthesia. Reference dose was estimated at point 5 mm from source. Brachytherapy was carried out in 10 fractions twice a day for 5 days. Patients received 60 Gy with BT alone, 45-55 Gy after ERT, and 50-55 Gy after chemotherapy. Local failure was found in 5 cases with T2 lesions. Recurrence occurred in 5 out of 27 cases with tumor thickness of 10 mm or less. On the other hand, there were no recurrences in 7 cases with tumor thickness of more than 10 mm. Among various types of treatment, BT following systemic chemotherapy or AI exhibited better results (local failure: 1/17) than other modalities. Lymph node metastases appeared in 11 cases. Cause specific survival was 91% at 2 years in all cases. Ulcerations of the tongue were noted in 7 in 26 evaluable cases. Although ulceration occurred in 6/13 cases treated until March 1994, the incidence decreased to 1/13 afterwards. Careful implantation and dose prescription contributed to the decrease in ulceration. Ulcerative lesions healed with conservative care within 6 months in all cases. Bone exposure occurred in 2 cases that received 60 Gy following AI for advanced diseases. HDR fractionated brachytherapy may be a workable alternative to LDR therapy for cancer of the tongue. Brachytherapy following chemotherapy can be applied to more advanced cases of the disease. (K.H.)

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

    Science.gov (United States)

    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

  10. 22: Use of a portable personal computer for treatment planning in intraoperative high-dose-rate brachytherapy

    International Nuclear Information System (INIS)

    An intraoperative high-dose-rate brachytherapy has been performed. A remote afterloading equipment with a small Ir-192 source was used. As applicators thin hollow steel needles are implanted into the tumor. The exact target volume is determined only during the operation. Therefore it is not possible to make a preoperative treatment plan. Thus use was made of a small portable computer system. The software designed by the authors allows the positions of the applicators and points of interest with prescribed doses to be input by means of a keyboard, a mouse or a digitizer. Using methods from nonlinear programming, the dwell times for each stopping point of the source are calculated in such a way that the prescribed doses in each point of interest are approximated as closely as possible. 7 refs.; 1 figure; 2 tabs

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

    International Nuclear Information System (INIS)

    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

  12. BEDVH--A method for evaluating biologically effective dose volume histograms: Application to eye plaque brachytherapy implants

    Energy Technology Data Exchange (ETDEWEB)

    Gagne, Nolan L.; Leonard, Kara L.; Huber, Kathryn E.; Mignano, John E.; Duker, Jay S.; Laver, Nora V.; Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Departments of Ophthalmology and Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

    2012-02-15

    Purpose: A method is introduced to examine the influence of implant duration T, radionuclide, and radiobiological parameters on the biologically effective dose (BED) throughout the entire volume of regions of interest for episcleral brachytherapy using available radionuclides. This method is employed to evaluate a particular eye plaque brachytherapy implant in a radiobiological context. Methods: A reference eye geometry and 16 mm COMS eye plaque loaded with {sup 103}Pd, {sup 125}I, or {sup 131}Cs sources were examined with dose distributions accounting for plaque heterogeneities. For a standardized 7 day implant, doses to 90% of the tumor volume ( {sub TUMOR}D{sub 90}) and 10% of the organ at risk volumes ( {sub OAR}D{sub 10}) were calculated. The BED equation from Dale and Jones and published {alpha}/{beta} and {mu} parameters were incorporated with dose volume histograms (DVHs) for various T values such as T = 7 days (i.e., {sub TUMOR} {sup 7}BED{sub 10} and {sub OAR} {sup 7}BED{sub 10}). By calculating BED throughout the volumes, biologically effective dose volume histograms (BEDVHs) were developed for tumor and OARs. Influence of T, radionuclide choice, and radiobiological parameters on {sub TUMOR}BEDVH and {sub OAR}BEDVH were examined. The nominal dose was scaled for shorter implants to achieve biological equivalence. Results: {sub TUMOR}D{sub 90} values were 102, 112, and 110 Gy for {sup 103}Pd, {sup 125}I, and {sup 131}Cs, respectively. Corresponding {sub TUMOR} {sup 7}BED{sub 10} values were 124, 140, and 138 Gy, respectively. As T decreased from 7 to 0.01 days, the isobiologically effective prescription dose decreased by a factor of three. As expected, {sub TUMOR} {sup 7}BEDVH did not significantly change as a function of radionuclide half-life but varied by 10% due to radionuclide dose distribution. Variations in reported radiobiological parameters caused {sub TUMOR} {sup 7}BED{sub 10} to deviate by up to 46%. Over the range of {sub OAR

  13. TMH index for an independent method of verification of a brachytherapy treatment plan on micro selectron high dose rate remote afterloading machine

    International Nuclear Information System (INIS)

    The purpose of this paper is to find an independent method for verification of a brachytherapy treatment plan on micro selectron high dose rate (HDR) remote afterloading machine. This TMH Index is simple to calculate prior to approving patient treatment execution at the treatment console as an independent check by the medical physicist. Also, it is sensitive enough to identify significant error in the dose specification points, dwell positions and/or prescribed dose for Rotterdam applications. Similar index may be derived for any other application, where dose specification points and type of applicator are constant

  14. Pulsed dose rate brachytherapy (PDR): an analysis of the technique at 2 years

    International Nuclear Information System (INIS)

    A total of 154 applications was analysed using a pulsed dose brachytherapy technique for 138 patients over a 2 year period with emphasis on technical aspects influencing the overall treatment time. Vaginal ovoids were used in 59 cases, plastic tubes in 52, a Fletcher-type in 18, vaginal cylinders in 14 and a perineal template in 11 cases. Pulses were given at hourly intervals with a median dose rate of 0.6 Gy per pulse (range 0.4 to 3 Gy). The number of pulses per application varied from 3 to 134 (median 32). The number of dwell positions varied from 1 to 542 over 1 to 18 catheters. Patient related problems were few. The room was entered almost every 77 minutes. We noted 561 status codes in 147 applications. Of the 25 different codes, the most frequent one was due to the door left open when a pulse had to be given (35%) or due to constriction of the plastic catheters at the transfer tube junction (26%). However, the median total treatment time was increased by only 5 minutes. With pulsed dose rate brachytherapy at hourly pulses we can treat our patients within the planned time despite frequent room entrance and occurrence of an appreciable number of status codes. This technique seems to fulfill its promise to replace low dose rate brachytherapy

  15. Pulsed dose rate brachytherapy (PDR): an analysis of the technique at 2 years

    Energy Technology Data Exchange (ETDEWEB)

    Thienpont, M. [Ghent Rijksuniversiteit (Belgium). Kliniek voor Radiotherapie en Kerngeneeskunde; Van Eijkeren, M.; Van Hecke, H.; Boterberg, T.; De Neve, W.

    1995-12-01

    A total of 154 applications was analysed using a pulsed dose brachytherapy technique for 138 patients over a 2 year period with emphasis on technical aspects influencing the overall treatment time. Vaginal ovoids were used in 59 cases, plastic tubes in 52, a Fletcher-type in 18, vaginal cylinders in 14 and a perineal template in 11 cases. Pulses were given at hourly intervals with a median dose rate of 0.6 Gy per pulse (range 0.4 to 3 Gy). The number of pulses per application varied from 3 to 134 (median 32). The number of dwell positions varied from 1 to 542 over 1 to 18 catheters. Patient related problems were few. The room was entered almost every 77 minutes. We noted 561 status codes in 147 applications. Of the 25 different codes, the most frequent one was due to the door left open when a pulse had to be given (35%) or due to constriction of the plastic catheters at the transfer tube junction (26%). However, the median total treatment time was increased by only 5 minutes. With pulsed dose rate brachytherapy at hourly pulses we can treat our patients within the planned time despite frequent room entrance and occurrence of an appreciable number of status codes. This technique seems to fulfill its promise to replace low dose rate brachytherapy.

  16. Low-dose-rate interstitial brachytherapy preserves good quality of life in buccal mucosa cancer patients

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the results and long-term changes in radiation toxicity of stage I-II buccal mucosa cancer patients treated by low-dose-rate (LDR) brachytherapy with 198Au grains. A total of 133 stage I-II buccal mucosa carcinomas patients received 198Au grain implantation brachytherapy between January 1982 and July 2005: 75 of them were treated by 198Au grain implantation alone and 58 were treated by 198Au implantation in combination with external irradiation. The average 198Au-grain dose was 70 Gy in 7 days. Gross tumor areas ranged from 2.4 cm2 to 9 cm2, and the clinical target areas ranged from 6 cm2 to 15 cm2. The follow-up periods ranged from 3 months to 20 years (mean: 5 years 11 months and median: 5 years 1 months). Failure at the site of the primary lesion occurred in 17 patients. Post-treatment mucosal ulceration developed in 15 patients, and all were cured within 25 months by conservative treatment. Osteoradionecrosis was diagnosed in 8 patients, but only one patient required surgical treatment. No severe complications or aggravation of complications developed more than 10 years after treatment. The results of low-dose-rate (LDR)-brachytherapy (BT) alone and LDR-BT in combination with external irradiation at a total dose of 25 Gy were acceptable from the standpoint of cure rate and quality of life (QOL). (author)

  17. Iododeoxyuridine radiosensitization by low- and high-energy photons for brachytherapy dose rates

    International Nuclear Information System (INIS)

    The dependence of iododeoxyuridine (IUdR) radiosensitization on photon energy and dose rate in the range of interest to brachytherapy was investigated by irradiating Chinese hamster cells in vitro under aerobic conditions. The radiosensitization produced by 10(-5) and 10(-4) M IUdR for 28-keV (average) photons from 125I, 60-keV photons from 241Am, and 830-keV (average) photons from 226Ra was measured at nominal dose rates of 0.17, 0.30, 0.57, and 0.73 Gy/h. Radiosensitization factors for IUdR were essentially independent of dose rate from 0.30 to 0.73 Gy/h for all cases except for 10(-4) M IUdR plus 241Am, in which case the radiosensitization factor increased from 2.5 +/- 0.2 to 3.0 +/- 0.1. In all cases, the radiosensitization factor decreased significantly as the dose rate was lowered from 0.30 to 0.17 Gy/h e.g., the radiosensitization factor for 241Am dropped to 1.9 +/- 0.2 at a dose rate of 0.17 Gy/h. Moreover, at 0.17 Gy/h the radiosensitization factors were essentially the same for all three photon energies. As the dose rate increased from 0.17 to 0.73 Gy/h, the difference between the radiosensitization factors for the three photon energies became larger; radiosensitization factors for 241Am were higher than those for 226Ra and 125I. In temporary brachytherapy the tumor is irradiated at the higher dose rate of about 0.50-0.70 Gy/h, while the normal tissues are irradiated at lower dose rates; the dose rate dependence of the radiosensitization factor may therefore lead to an improvement in the therapeutic ratio for brachytherapy in combination with IUdR

  18. Time, dose and volume factors in interstitial brachytherapy combined with external irradiation for oral tongue carcinoma

    International Nuclear Information System (INIS)

    This is a retrospective analysis of 136 patients with squamous cell carcinoma of stages I and II of the oral tongue who were treated with interstitial brachytherapy alone or in combination with external irradiation between 1976 and 1991. Control of the primary lesion and the occurrence of late complications were analyzed with respect to dose, time and tumor size with the Cox hazard model. The 5-year survival rates for stages I and II were 84.5% and 75.6%. The 5-year primary control rate was 91.3% for stage I and 77.3% for stage II (p50 Gy compared with a brachytherapy dose 30 mm. Late complications should be reduced by using a spacer, improvements in dental and oral hygiene, and a sophisticated implant method. (author)

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

    International Nuclear Information System (INIS)

    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. Dose volume histogram analysis of normal structures associated with accelerated partial breast irradiation delivered by high dose rate brachytherapy and comparison with whole breast external beam radiotherapy fields

    Directory of Open Access Journals (Sweden)

    Mutyala Subhakar

    2008-11-01

    Full Text Available Abstract Purpose To assess the radiation dose delivered to the heart and ipsilateral lung during accelerated partial breast brachytherapy using a MammoSite™ applicator and compare to those produced by whole breast external beam radiotherapy (WBRT. Materials and methods Dosimetric analysis was conducted on patients receiving MammoSite breast brachytherapy following conservative surgery for invasive ductal carcinoma. Cardiac dose was evaluated for patients with left breast tumors with a CT scan encompassing the entire heart. Lung dose was evaluated for patients in whom the entire lung was scanned. The prescription dose of 3400 cGy was 1 cm from the balloon surface. MammoSite dosimetry was compared to simulated WBRT fields with and without radiobiological correction for the effects of dose and fractionation. Dose parameters such as the volume of the structure receiving 10 Gy or more (V10 and the dose received by 20 cc of the structure (D20, were calculated as well as the maximum and mean doses received. Results Fifteen patients were studied, five had complete lung data and six had left-sided tumors with complete cardiac data. Ipsilateral lung volumes ranged from 925–1380 cc. Cardiac volumes ranged from 337–551 cc. MammoSite resulted in a significantly lower percentage lung V30 and lung and cardiac V20 than the WBRT fields, with and without radiobiological correction. Conclusion This study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator. The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated WBRT fields of the same CT data sets. Trial registration Dana Farber Trial Registry number 03-179

  1. SU-E-T-546: Use of Implant Volume for Quality Assurance of Low Dose Rate Brachytherapy Treatment Plans

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, D; Kolar, M [Radiation Oncology, Cleveland Clinic Foundation, Cleveland, OH (United States)

    2014-06-01

    Purpose: To analyze the application of volume implant (V100) data as a method for a global check of low dose rate (LDR) brachytherapy plans. Methods: Treatment plans for 335 consecutive patients undergoing permanent seed implants for prostate cancer and for 113 patients treated with plaque therapy for ocular melanoma were analyzed. Plaques used were 54 COMS (10 to 20 mm, notched and regular) and 59 Eye Physics EP917s with variable loading. Plots of treatment time x implanted activity per unit dose versus v100 ^.667 were made. V100 values were obtained using dose volume histograms calculated by the treatment planning systems (Variseed 8.02 and Plaque Simulator 5.4). Four different physicists were involved in planning the prostate seed cases; two physicists for the eye plaques. Results: Since the time and dose for the prostate cases did not vary, a plot of implanted activity vs V100 ^.667 was made. A linear fit with no intercept had an r{sup 2} = 0.978; more than 94% of the actual activities fell within 5% of the activities calculated from the linear fit. The greatest deviations were in cases where the implant volumes were large (> 100 cc). Both COMS and EP917 plaque linear fits were good (r{sup 2} = .967 and .957); the largest deviations were seen for large volumes. Conclusions: The method outlined here is effective for checking planning consistency and quality assurance of two types of LDR brachytherapy treatment plans (temporary and permanent). A spreadsheet for the calculations enables a quick check of the plan in situations were time is short (e.g. OR-based prostate planning)

  2. SU-E-T-546: Use of Implant Volume for Quality Assurance of Low Dose Rate Brachytherapy Treatment Plans

    International Nuclear Information System (INIS)

    Purpose: To analyze the application of volume implant (V100) data as a method for a global check of low dose rate (LDR) brachytherapy plans. Methods: Treatment plans for 335 consecutive patients undergoing permanent seed implants for prostate cancer and for 113 patients treated with plaque therapy for ocular melanoma were analyzed. Plaques used were 54 COMS (10 to 20 mm, notched and regular) and 59 Eye Physics EP917s with variable loading. Plots of treatment time x implanted activity per unit dose versus v100 ^.667 were made. V100 values were obtained using dose volume histograms calculated by the treatment planning systems (Variseed 8.02 and Plaque Simulator 5.4). Four different physicists were involved in planning the prostate seed cases; two physicists for the eye plaques. Results: Since the time and dose for the prostate cases did not vary, a plot of implanted activity vs V100 ^.667 was made. A linear fit with no intercept had an r2 = 0.978; more than 94% of the actual activities fell within 5% of the activities calculated from the linear fit. The greatest deviations were in cases where the implant volumes were large (> 100 cc). Both COMS and EP917 plaque linear fits were good (r2 = .967 and .957); the largest deviations were seen for large volumes. Conclusions: The method outlined here is effective for checking planning consistency and quality assurance of two types of LDR brachytherapy treatment plans (temporary and permanent). A spreadsheet for the calculations enables a quick check of the plan in situations were time is short (e.g. OR-based prostate planning)

  3. Dosimetry measurements at close range to high dose-rate brachytherapy for endovascular irradiation

    International Nuclear Information System (INIS)

    Purpose/Objective: Transluminal angioplasty in peripheral as well as coronary arteries has been an important treatment approach for arterial occlusive diseases. However, the major limitation seems to be that more than 40% of the treated arteries undergo restenosis or reocclusion within the first year. There have been some reports that endovascular brachytherapy may be useful to prevent arterial restenosis. According to the recently organized randomized study, the dose will be prescribed at the depth of one-half the luminal diameter plus 0.2 mm (round up to the nearest half millimeter) for 14 Gray using the Ir-192 high dose-rate (HDR) remote afterloading device. There is no reliable dosimetry data measured at millimeter range. The purpose of this paper is to accurately measure the specific dose rate per curie at close millimeter range for high activity iridium-192 source in HDR machine. Material and Methods: A plastic tissue-equivalent phantom was specially designed and built for this experiment. A small hole was drilled into the phantom to simulate the artery and big enough to fit a 6F luminal catheter used to position the radiation source in phantom. The high activity iridiu source from the Nucletron remote afterloading device was used and programmed to the predetermined positions. Since the measurements were required for high spatial resolutions, both low sensitivity films and mini-thermoluminescent dosimeters (TLD) of 1 mm3 in size were used for dose measurements. The measurements were performed repeatedly for better statistical accuracy. Prior to exposure, the films were cut in an appropriate size and sandwiched between two halves of the phantom sealed with light-proof tape. The source was run to the preset dwell position and dwell time to expose the film to a density of between 2 to 3. The exposed films were then developed and scanned with an automatic optical density scanner and then the results were converted to absorbed doses. The aperture size effect is

  4. Analysis of environmental and occupational doses from brachytherapy procedures

    International Nuclear Information System (INIS)

    Lithium Fluoride Thermoluminescent detectors (TLD) were used to obtain the doses received by a physician and a physicist involved in braquitherapy procedures and also in measuring the dose in the treatment room. From the results, one can infer that: the physicist receives in his hands six times more doses preparing the probes, than the physician inserting them; the braquitherapy procedures, alone, are responsible for almost 25% of the total dose related to all radiotherapy activities; the environmental measurement doses related to high dose ratio were higher when compared to low dose ratio doses, once the radiation activity used was higher. From the results one can also infer that having a TLD dosimetry system for radiotherapy routine can be useful also to obtain the doses for radiation workers or for environment radiation in order to contribute to the institution quality assurance. (author)

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

    Science.gov (United States)

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

    2015-06-01

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

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

    International Nuclear Information System (INIS)

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

  7. High-dose-rate brachytherapy for cervical carcinoma patients with narrow vagina

    Energy Technology Data Exchange (ETDEWEB)

    Yorozu, Atsunori; Toya, Kazuhito; Kawase, Takatugu [National Tokyo Medical Center, Tokyo (Japan); Dokiya, Takushi [Saitama Medical Coll., Moroyama (Japan)

    2002-06-01

    We retrospectively analyzed cervical cancer patients with narrow vagina treated by high-dose-rate (HDR) brachytherapy followed by external beam irradiation. Fifty patients were treated with radical radiotherapy between 1992 and 1999 at the National Tokyo Medical Center. All patients received 30 Gy of external whole pelvic irradiation and 20 Gy of pelvic irradiation with a central shield. After 30 Gy of whole pelvic irradiation, 24 Gy of fractionated brachytherapy was applied with a tandem and ovoids, non-rigid type developed in the Cancer Institute, according to the Manchester method. Nineteen patients with a narrow vagina of less than 40 mm in width were compared with 31 other patients (control group). The 5-year cumulative survival rates were 56% in the patients with a narrow vagina and 53% in the control group (P=0.6008). The control rate in the pelvis was not significantly different between the two groups. The cumulative rate of rectal complications of the patients with a narrow vagina was more frequent than the control group (58% vs 29%) (P=0.0924). Severe rectal bleeding was also more frequent in the patients with a narrow vagina. The estimated maximal dose of the rectal wall was significantly higher in patients with a narrow vagina. This result suggests that a lower brachytherapy dose is necessary for patients with narrow vagina considering the rectal sequelae in the case of using our methods. (author)

  8. Survey of high-dose-rate prostate brachytherapy practice in Australia and New Zealand, 2010-2011

    International Nuclear Information System (INIS)

    A survey was designed to establish a baseline data set for the current routine practice of high-dose-rate prostate brachytherapy (HDR-PB) in Australia and New Zealand. Existing treatment protocols and clinical implementations are not generally known. The survey, for the 2010 and 2011 calendar years, collected data including number of patients treated; equipment used; imaging modalities; applicator verification and correction methods; dose prescriptions and normal tissue dose constraints. The number of HDR-PB patients treated was compared with the most recently published prostate cancer incidence data in Australia and in New Zealand. Total biologically equivalent doses in 2.0Gy fractions (EQD2) were calculated for each prescription regime reported. There were reductions, of 25-60%, in patients treated with HDR-PB from 2010 to 2011 in four departments. Prostate cancer patients are two to six times more likely to be prescribed HDR-PB in Western Australia than elsewhere in the region. There were 12 different treatment prescriptions, with EQD2 doses ranging from 73.5 to 97.6Gy, among the 18 reported by survey respondents. Normal tissue definition methodology and dose constraints varied, and 13 of 15 departments reported that no particular published external guidelines were followed in full. The high survey response rate, 15 of 17 departments, has provided a representative baseline data set of contemporary HDR-PB practice in Australia and New Zealand that may assist government and professional bodies, such as the Australasian Brachytherapy Group, in formulating recommendations, setting standards and future planning.

  9. Implementation of three-dimensional planning in brachytherapy of high dose rate for gynecology therapies

    International Nuclear Information System (INIS)

    This work aims to implement the three-dimensional (3D) planning for gynecological brachytherapy treatments. For this purpose, tests of acceptance and commissioning of brachytherapy equipment were performed to establish a quality and periodic assurance program. For this purpose, an important step was searching for a material to be used as a dummy source, since the applicators do not have any specific dummy. In addition, the validation of the use of applicators library was made for reconstruction in computed tomography (CT) and magnetic resonance imaging (MRI). In order to validate 3D planning, comparison of doses in dose assessment points used in bidimensional (2D) plans have been performed with volumetric doses to adjacent organs to the tumor. Finally, a protocol was established for 3D brachytherapy planning alternately using magnetic resonance image (MRI) and CT images, making evaluation of the dose in the tumor through the recording of MR and CT images. It was not possible to find a suitable material that could be used as dummy in MRI. However, the acquisition of the license's library for the applicators made possible the 3D planning based on MRI. No correlation was found between volumetric and specific doses analyzed, showing the importance of the implementation of 3D planning. The average ratio between D2cc and ICRUBladder dose was 1,74, 22% higher than the ratio found by others authors. For the rectum, D2cc was less than dose point for 60% of fractions; the average difference was 12,5%. The average ratio between D2cc and point dose rectum, 0,85, is equivalent to the value showed by Kim et al, 0,91. The D2cc for sigmoid was 69% higher than point dose used, unless it was not possible compare this value, since the sigmoid point used in the 2D procedures is not used in others institutes. Relative dose in 2 cc of sigmoid was 57% of the prescription dose, the same value was found by in literature. This work enabled the implementation of a viable brachytherapy 3

  10. The Preliminary Prototype of Medium Dose Rate Brachytherapy Equipment

    Directory of Open Access Journals (Sweden)

    A. Satmoko

    2013-08-01

    Full Text Available A preliminary prototype of a brachytherapy equipment has been constructed. The work started by developing conceptual design, followed by basic design and detailed design. In the conceptual design, design requirements are stated. In the basic design, technical specifications for main components are determined. In detailed design, general drawings are discussed. The prototype consists of three main systems: a mechanical system, an instrumentation system, and a safety system. The mechanical system assures the movement mechanism of the isotope source position beginning from the standby position until the applicators. It consists of three main modules: a position handling module, a container module, and a channel distribution module. The position handling module serves to move the isotope source position. As shielding, the second module is to store the source when the equipment is in standby position. The prototype provides 12 output channels. The channel selection is performed by the third module. The instrumentation system controls the movement of source position by handling motor operations. It consists of several modules. A microcontroller module serves as a control center whose task includes both controlling motors and communicating with computer. A motor module serves to handle motors. 10 sensors, including their signal conditionings, are introduced to read the environment conditions of the equipment. LEDs are used to display these conditions. In order to facilitate the operators’ duty, communication via RS232 is provided. The brachytherapy equipment can therefore be operated by using computer. Interface software is developed using C# language. To complete both mechanical and instrumentation systems performance, a safety system is developed to make sure that the safety for operator and patients from receiving excessive radiation. An interlock system is introduced to guard against abnormal conditions. In the worst case, a manual intervention

  11. Treatment Outcome of Medium-Dose-Rate Intracavitary Brachytherapy for Carcinoma of the Uterine Cervix: Comparison With Low-Dose-Rate Intracavitary Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kaneyasu, Yuko, E-mail: kaneyasu@hiroshima-u.ac.jp [Department of Radiation Oncology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima (Japan); Department of Radiation Oncology, Tokyo Women' s Medical University, Tokyo (Japan); Kita, Midori [Department of Radiation Oncology, Tokyo Women' s Medical University, Tokyo (Japan); Department of Clinical Radiology, Tokyo Metropolitan Tama Medical Center, Tokyo (Japan); Okawa, Tomohiko [Evaluation and Promotion Center, Utsunomiya Memorial Hospital, Tochigi (Japan); Maebayashi, Katsuya [Department of Radiation Oncology, Tokyo Women' s Medical University, Tokyo (Japan); Kohno, Mari [Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women' s Medical University Hospital, Tokyo (Japan); Sonoda, Tatsuo; Hirabayashi, Hisae [Department of Radiology, Tokyo Women' s Medical University Hospital, Tokyo (Japan); Nagata, Yasushi [Department of Radiation Oncology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima (Japan); Mitsuhashi, Norio [Department of Radiation Oncology, Tokyo Women' s Medical University, Tokyo (Japan)

    2012-09-01

    Purpose: To evaluate and compare the efficacy of medium-dose-rate (MDR) and low-dose-rate (LDR) intracavitary brachytherapy (ICBT) for uterine cervical cancer. Methods and Materials: We evaluated 419 patients with squamous cell carcinoma of the cervix who were treated by radical radiotherapy with curative intent at Tokyo Women's Medical University from 1969 to 1999. LDR was used from 1969 to 1986, and MDR has been used since July 1987. When compared with LDR, fraction dose was decreased and fraction size was increased (1 or 2 fractions) for MDR to make the total dose of MDR equal to that of LDR. In general, the patients received a total dose of 60 to 70 Gy at Point A with external beam radiotherapy combined with brachytherapy according to the International Federation of Gynecology and Obstetrics stage. In the LDR group, 32 patients had Stage I disease, 81 had Stage II, 182 had Stage III, and 29 had Stage IVA; in the MDR group, 9 patients had Stage I disease, 19 had Stage II, 55 had Stage III, and 12 had Stage IVA. Results: The 5-year overall survival rates for Stages I, II, III, and IVA in the LDR group were 78%, 72%, 55%, and 34%, respectively. In the MDR group, the 5-year overall survival rates were 100%, 68%, 52%, and 42%, respectively. No significant statistical differences were seen between the two groups. The actuarial rates of late complications Grade 2 or greater at 5 years for the rectum, bladder, and small intestine in the LDR group were 11.1%, 5.8%, and 2.0%, respectively. The rates for the MDR group were 11.7%, 4.2%, and 2.6%, respectively, all of which were without statistical differences. Conclusion: These data suggest that MDR ICBT is effective, useful, and equally as good as LDR ICBT in daytime (about 5 hours) treatments of patients with cervical cancer.

  12. Treatment Outcome of Medium-Dose-Rate Intracavitary Brachytherapy for Carcinoma of the Uterine Cervix: Comparison With Low-Dose-Rate Intracavitary Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To evaluate and compare the efficacy of medium-dose-rate (MDR) and low-dose-rate (LDR) intracavitary brachytherapy (ICBT) for uterine cervical cancer. Methods and Materials: We evaluated 419 patients with squamous cell carcinoma of the cervix who were treated by radical radiotherapy with curative intent at Tokyo Women’s Medical University from 1969 to 1999. LDR was used from 1969 to 1986, and MDR has been used since July 1987. When compared with LDR, fraction dose was decreased and fraction size was increased (1 or 2 fractions) for MDR to make the total dose of MDR equal to that of LDR. In general, the patients received a total dose of 60 to 70 Gy at Point A with external beam radiotherapy combined with brachytherapy according to the International Federation of Gynecology and Obstetrics stage. In the LDR group, 32 patients had Stage I disease, 81 had Stage II, 182 had Stage III, and 29 had Stage IVA; in the MDR group, 9 patients had Stage I disease, 19 had Stage II, 55 had Stage III, and 12 had Stage IVA. Results: The 5-year overall survival rates for Stages I, II, III, and IVA in the LDR group were 78%, 72%, 55%, and 34%, respectively. In the MDR group, the 5-year overall survival rates were 100%, 68%, 52%, and 42%, respectively. No significant statistical differences were seen between the two groups. The actuarial rates of late complications Grade 2 or greater at 5 years for the rectum, bladder, and small intestine in the LDR group were 11.1%, 5.8%, and 2.0%, respectively. The rates for the MDR group were 11.7%, 4.2%, and 2.6%, respectively, all of which were without statistical differences. Conclusion: These data suggest that MDR ICBT is effective, useful, and equally as good as LDR ICBT in daytime (about 5 hours) treatments of patients with cervical cancer.

  13. SU-E-T-55: Biological Equivalent Dose (BED) Comparison Between Permanent Interstitial Brachytherapy and Conventional External Beam Radiotherapy for Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: The goal of this research is to calculate and compare the Biological Equivalent Dose (BED) between permanent prostate Iodine-125 implant brachytherapy as monotherapy with the BED of conventional external beam radiation therapy (EBRT). Methods: A retrospective study of 605 patients treated with Iodine-125 seed implant was performed in which physician A treated 274 patients and physician B treated 331 patients. All the Brachytherapy treatment plans were created using VariSeed 8 planning system. The Iodine-125 seed source activities and loading patterns varied slightly between the two physicians. The prescription dose is 145 Gy to PTV for each patient. The BED and Tumor Control Probability (TCP) were calculated based on the TG 137 formulas. The BED for conventional EBRT of the prostate given in our institution in 2Gy per fraction for 38 fractions was calculated and compared. Results: Physician A treated 274 patients with an average BED of 123.92±0.87 Gy and an average TCP of 99.20%; Physician B treated 331 patients with an average BED of 124.87±1.12 Gy and an average TCP of 99.30%. There are no statistically significant differences (T-Test) between the BED and TCP values calculated for these two group patients.The BED of the patients undergoing conventional EBRT is calculated to be 126.92Gy. The BED of the patients treated with permanent implant brachytherapy and EBRT are comparable. Our BED and TCP values are higher than the reported values by TG 137 due to higher Iodine-125 seed activity used in our institution. Conclusion: We calculated the BED,a surrogate of the biological response to a permanent prostate brachytherapy using TG 137 formulas and recommendation. The TCP of better than 99% is calculated for these patients. A clinical outcome study of these patients correlating the BED and TCP values with PSA and Gleason Levels as well as patient survival is warranted

  14. A well chamber method of measuring the transit dose of an hour brachytherapy unit

    International Nuclear Information System (INIS)

    Full text: Treatment planning for high dose rate (HDR) brachytherapy with a single stepping-source generally neglects the transit dose. The transit dose due to the source movement comprises entry, interdwell and exit components. There is a lack of reliable results reported in the literature on transit dose and this leads to difficulties in predicting its significance in some clinical situations. This study investigates the effects of the transit dose in the planning target volume (PTV) of a HDR brachytherapy unit. A well-type chamber was used to determine the dose differences between two sets of measurements, one being the stationary dose only and the other being the sum of stationary and transit doses. The entry and exit components of the transit dose were also measured. Single catheters of active lengths of 20 and 40 mm, different dwell times of 0.5, 1,2 and 5 s and different step sizes of 2.5, 5 and 10 mm were used in the measurements with the well-type chamber. The measured dose differences between stationary and stationary plus transit source movement in most clinical cases were within 2%. The additional dose due to the source transit can be as high as 25% for the case of 0.5 s dwell time, 10 mm step-size and 20 m active length. For this particular case, the dose at 10 mm on the transverse bisector would be 11 cGy, which is far less than a typical prescribed dose. It is found that the transit dose to the PTV in most clinical cases is within 2% and is negligible. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine

  15. A dosimetric study of polyethylene glycol hydrogel in 200 prostate cancer patients treated with high-dose rate brachytherapy ± intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on rectal doses in prostate cancer patients undergoing radiotherapy. Materials and methods: Between July 2009 and April 2013, we treated 200 clinically localized prostate cancer patients with high-dose rate (HDR) brachytherapy ± intensity modulated radiation therapy. Half of the patients received a transrectal ultrasound (TRUS)-guided transperineal injection of 10 mL PEG hydrogel (DuraSeal™ Spinal Sealant System; Covidien, Mansfield, MA) in their anterior perirectal fat immediately prior to the first HDR brachytherapy treatment and 5 mL PEG hydrogel prior to the second HDR brachytherapy treatment. Prostate, rectal, and bladder doses and prostate–rectal distances were calculated based upon treatment planning CT scans. Results: There was a success rate of 100% (100/100) with PEG hydrogel implantation. PEG hydrogel significantly increased the prostate–rectal separation (mean ± SD, 12 ± 4 mm with gel vs. 4 ± 2 mm without gel, p < 0.001) and significantly decreased the mean rectal D2 mL (47 ± 9% with gel vs. 60 ± 8% without gel, p < 0.001). Gel decreased rectal doses regardless of body mass index (BMI). Conclusions: PEG hydrogel temporarily displaced the rectum away from the prostate by an average of 12 mm and led to a significant reduction in rectal radiation doses, regardless of BMI

  16. Evaluation of physician eye lens doses during permanent seed implant brachytherapy for prostate cancer

    International Nuclear Information System (INIS)

    Treatment of low grade prostate cancer with permanent implant of radioactive seeds has become one of the most common brachytherapy procedures in use today. The implant procedure is usually performed with fluoroscopy image guidance to ensure that the seeds are deployed in the planned locations. In this situation the physician performing the transperineal implant is required to be close to the fluoroscopy unit and dose to the eye lens may be of concern. In 1991 the International Commission on Radiological Protection (ICRP) provided a recommended dose limit of 150 mSv yr−1 for occupational exposures to the lens of the eye. With more long term follow-up data, this limit was revised in 2011 to 20 mSv yr−1. With this revised limit in mind, we have investigated the dose to the lens of the eye received by physicians during prostate brachytherapy seed implantation. By making an approximation of annual workload, we have related the dose received to the annual background dose. Through clinical and phantom measurements with thermoluminescent dosimeters, it was found that the excess dose to the physician’s eye lens received for a conservative estimate of annual workload was never greater than 100% of the annual background dose. (paper)

  17. Is the Use of a Surrogate Urethra an Option in Prostate High-Dose-Rate Brachytherapy?

    International Nuclear Information System (INIS)

    Purpose: To investigate the accuracy and the dosimetric consequences of substituting a surrogate urethra assumed to be at the geometric center of the prostate, in place of the true urethra when using high-dose-rate (HDR) brachytherapy for the treatment of prostate cancer. Methods and Materials: One hundred prostate cancer patients treated with HDR brachytherapy constituted the study group. A pre-plan was made with the urethra visualized. The true urethra was defined, and a surrogate urethra was placed at the geometric center of the prostate. The distance between the two urethras was measured. The deviation was evaluated at the base, middle, and apex. To evaluate the dosimetric consequences for the true urethra when using a surrogate urethra, two different dose plans were made: one based on the true urethra and one based on the surrogate urethra. The dose-volume histograms for the true urethra were analyzed. Results: The deviation between the true urethra and the surrogate urethra was greatest at the base of the prostate. A statistically significant difference was seen between the dosimetric parameters for the true and the surrogate urethra when the dose plan was made using the surrogate urethra. In this situation the dose to the true urethra was increased above our defined maximum tolerance limit. Conclusions: When using dose plans made according to a surrogate urethra the dose to the true urethra might be too high to be acceptable. If the true urethra is not visualized, severe damage could easily develop in a significant number of patients

  18. External beam radiation therapy followed by high-dose-rate brachytherapy for inoperable superficial esophageal carcinoma

    International Nuclear Information System (INIS)

    Purpose: The aim of this study was to retrospectively evaluate the feasibility, efficacy, and tolerance of external beam radiotherapy followed by high-dose-rate brachytherapy in inoperable patients with superficial esophageal cancer. Patients and Methods: From November 1992 to May 1999, 66 patients with superficial esophageal cancer were treated with exclusive radiotherapy. The median age was 60 years (range, 41-85). Fifty-three percent of them were ineligible for surgery owing to synchronous or previously treated head-and-neck cancer. Most of the patients (n = 49) were evaluated with endoscopic ultrasonography (EUS) or computed tomography (CT). The mean doses of external beam radiotherapy and high-dose rate brachytherapy were 57.1 Gy (±4.83) and 8.82 Gy (±3.98), respectively. The most frequently used regimen was 60 Gy followed by 7 Gy at 5 mm depth in two applications. Results: Among patients evaluated with EUS or CT, the complete response rate was 98%. The 3-, 5-, and 7-year survival rates were 57.9%, 35.6%, and 26.6%, respectively. Median overall survival was 3.8 years. The 5-year relapse-free survival and cause-specific survival were 54.6% and 76.9%. The 5-year overall, relapse-free, and cause-specific survival of the whole population of 66 patients was 33%, 53%, and 77%, respectively. Local failure occurred in 15 of 66 patients; 6 were treated with brachytherapy. Severe late toxicity (mostly esophageal stenosis) rated according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale occurred in 6 of 66 patients (9%). Conclusion: This well tolerated regimen may be a therapeutic alternative for inoperable patients with superficial esophageal cancer. Only a randomized study could be able to check the potential benefit of brachytherapy after external beam radiation in superficial esophageal cancer

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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.

  1. A linear programming model for optimizing HDR brachytherapy dose distributions with respect to mean dose in the DVH-tail

    International Nuclear Information System (INIS)

    Purpose: Recent research has shown that the optimization model hitherto used in high-dose-rate (HDR) brachytherapy corresponds weakly to the dosimetric indices used to evaluate the quality of a dose distribution. Although alternative models that explicitly include such dosimetric indices have been presented, the inclusion of the dosimetric indices explicitly yields intractable models. The purpose of this paper is to develop a model for optimizing dosimetric indices that is easier to solve than those proposed earlier.Methods: In this paper, the authors present an alternative approach for optimizing dose distributions for HDR brachytherapy where dosimetric indices are taken into account through surrogates based on the conditional value-at-risk concept. This yields a linear optimization model that is easy to solve, and has the advantage that the constraints are easy to interpret and modify to obtain satisfactory dose distributions.Results: The authors show by experimental comparisons, carried out retrospectively for a set of prostate cancer patients, that their proposed model corresponds well with constraining dosimetric indices. All modifications of the parameters in the authors' model yield the expected result. The dose distributions generated are also comparable to those generated by the standard model with respect to the dosimetric indices that are used for evaluating quality.Conclusions: The authors' new model is a viable surrogate to optimizing dosimetric indices and quickly and easily yields high quality dose distributions

  2. CT-guided brachytherapy of prostate cancer: reduction of effective dose from X-ray examination

    Science.gov (United States)

    Sanin, Dmitriy B.; Biryukov, Vitaliy A.; Rusetskiy, Sergey S.; Sviridov, Pavel V.; Volodina, Tatiana V.

    2014-03-01

    Computed tomography (CT) is one of the most effective and informative diagnostic method. Though the number of CT scans among all radiographic procedures in the USA and European countries is 11% and 4% respectively, CT makes the highest contribution to the collective effective dose from all radiographic procedures, it is 67% in the USA and 40% in European countries [1-5]. Therefore it is necessary to understand the significance of dose value from CT imaging to a patient . Though CT dose from multiple scans and potential risk is of great concern in pediatric patients, this applies to adults as well. In this connection it is very important to develop optimal approaches to dose reduction and optimization of CT examination. International Commission on Radiological Protection (ICRP) in its publications recommends radiologists to be aware that often CT image quality is higher than it is necessary for diagnostic confidence[6], and there is a potential to reduce the dose which patient gets from CT examination [7]. In recent years many procedures, such as minimally invasive surgery, biopsy, brachytherapy and different types of ablation are carried out under guidance of computed tomography [6;7], and during a procedures multiple CT scans focusing on a specific anatomic region are performed. At the Clinics of MRRC different types of treatment for patients with prostate cancer are used, incuding conformal CT-guided brachytherapy, implantation of microsources of I into the gland under guidance of spiral CT [8]. So, the purpose of the study is to choose optimal method to reduce radiation dose from CT during CT-guided prostate brachytherapy and to obtain the image of desired quality.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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.

  5. Partial breast irradiation with interstitial high dose-rate brachytherapy: acute and late toxicities and cosmetic results

    International Nuclear Information System (INIS)

    Accelerated partial breast irradiation aims at decreasing the overall treatment time and reducing toxicity. The study we report is for early stage breast cancer and is a multicentre clinical investigation of partial breast irradiation achieved by interstitial high dose-rate (HDR) brachytherapy with intraoperative placement of catheters. We have been able to conclude from the initial data that an interstitial perioperative brachytherapy implant is a feasible method of treatment with good tolerance and good cosmetic results. (author)

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

    International Nuclear Information System (INIS)

    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

  7. Dosimetric equivalence of non-standard high dose rate (HDR) brachytherapy catheter patterns

    CERN Document Server

    Cunha, J Adam M; Pouliot, Jean

    2009-01-01

    Purpose: To determine whether alternative HDR prostate brachytherapy catheter patterns can result in improved dose distributions while providing better access and reducing trauma. Methods: Prostate HDR brachytherapy uses a grid of parallel needle positions to guide the catheter insertion. This geometry does not easily allow the physician to avoid piercing the critical structures near the penile bulb nor does it provide position flexibility in the case of pubic arch interference. On CT data from ten previously-treated patients new catheters were digitized following three catheter patterns: conical, bi-conical, and fireworks. The conical patterns were used to accommodate a robotic delivery using a single entry point. The bi-conical and fireworks patterns were specifically designed to avoid the critical structures near the penile bulb. For each catheter distribution, a plan was optimized with the inverse planning algorithm, IPSA, and compared with the plan used for treatment. Irrelevant of catheter geometry, a p...

  8. Ruthenium-106 brachytherapy for thick uveal melanoma: reappraisal of apex and base dose radiation and dose rate

    Science.gov (United States)

    Jaberi, Ramin; Sedaghat, Ahad; Azma, Zohreh; Nojomi, Marzieh; Falavarjani, Khalil Ghasemi; Nazari, Hossein

    2016-01-01

    Purpose To evaluate the outcomes of ruthenium-106 (106Ru) brachytherapy in terms of radiation parameters in patients with thick uveal melanomas. Material and methods Medical records of 51 patients with thick (thickness ≥ 7 mm and < 11 mm) uveal melanoma treated with 106Ru brachytherapy during a ten-year period were reviewed. Radiation parameters, tumor regression, best corrected visual acuity (BCVA), and treatment-related complications were assessed. Results Fifty one eyes of 51 consecutive patients including 25 men and 26 women with a mean age of 50.5 ± 15.2 years were enrolled. Patients were followed for 36.1 ± 26.5 months (mean ± SD). Mean radiation dose to tumor apex and to sclera were 71 (± 19.2) Gy and 1269 (± 168.2) Gy. Radiation dose rates to tumor apex and to sclera were 0.37 (± 0.14) Gy/h and 6.44 (± 1.50) Gy/h. Globe preservation was achieved in 82.4%. Preoperative mean tumor thickness of 8.1 (± 0.9) mm decreased to 4.5 (± 1.6) mm, 3.4 (± 1.4) mm, and 3.0 (± 1.46) mm at 12, 24, and 48 months after brachytherapy (p = 0.03). Four eyes that did not show regression after 6 months of brachytherapy were enucleated. Secondary enucleation was performed in 5 eyes because of tumor recurrence or neovascular glaucoma. Tumor recurrence was evident in 6 (11.8%) patients. Mean Log MAR (magnification requirement) visual acuity declined from 0.75 (± 0.63) to 0.94 (± 0.5) (p = 0.04). Best corrected visual acuity of 20/200 or worse was recorded in 37% of the patients at the time of diagnosis and 61.7% of the patients at last exam (p = 0.04). Non-proliferative and proliferative radiation-induced retinopathy was observed in 20 and 7 eyes. Conclusions Thick uveal melanomas are amenable to 106Ru brachytherapy with less than recommended apex radiation dose and dose rates. PMID:26985199

  9. 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

    International Nuclear Information System (INIS)

    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

  10. Characterisation of a Fricke gel compound adopted to produce dosimetric catheters for in vivo dose measurements in HDR brachytherapy

    International Nuclear Information System (INIS)

    Radiation doses delivered to the patient during high dose rate brachytherapy treatments are susceptible to many inaccuracies and may not accurately match the planned doses. Novel Fricke gel dosimetric catheters (FGDC) were developed in the laboratory to be used for in vivo measurements of high dose rate brachytherapy treatments and represent possible tools to increase treatment accuracy. In this study, the dosimetric compound adopted to achieve FGDC was studied in terms of dose sensitivity and linearity, and some potentialities and limits of its application were investigated. Results show that at doses higher than 400 cGy, the dosimeter response is linear with the delivered dose until a saturation effect is observed at doses higher than 2800 cGy. However, saturation is reached at lower doses as well with dose rates higher than 400 cGy/min.

  11. Characterisation of a Fricke gel compound adopted to produce dosimetric catheters for in vivo dose measurements in HDR brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-01

    Radiation doses delivered to the patient during high dose rate brachytherapy treatments are susceptible to many inaccuracies and may not accurately match the planned doses. Novel Fricke gel dosimetric catheters (FGDC) were developed in the laboratory to be used for in vivo measurements of high dose rate brachytherapy treatments and represent possible tools to increase treatment accuracy. In this study, the dosimetric compound adopted to achieve FGDC was studied in terms of dose sensitivity and linearity, and some potentialities and limits of its application were investigated. Results show that at doses higher than 400 cGy, the dosimeter response is linear with the delivered dose until a saturation effect is observed at doses higher than 2800 cGy. However, saturation is reached at lower doses as well with dose rates higher than 400 cGy/min.

  12. New Brachytherapy Standards Paradigm Shift

    International Nuclear Information System (INIS)

    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

  13. Development of 3D ultrasound needle guidance for high-dose-rate interstitial brachytherapy of gynaecological cancers

    Science.gov (United States)

    Rodgers, J.; Tessier, D.; D'Souza, D.; Leung, E.; Hajdok, G.; Fenster, A.

    2016-04-01

    High-dose-rate (HDR) interstitial brachytherapy is often included in standard-of-care for gynaecological cancers. Needles are currently inserted through a perineal template without any standard real-time imaging modality to assist needle guidance, causing physicians to rely on pre-operative imaging, clinical examination, and experience. While two-dimensional (2D) ultrasound (US) is sometimes used for real-time guidance, visualization of needle placement and depth is difficult and subject to variability and inaccuracy in 2D images. The close proximity to critical organs, in particular the rectum and bladder, can lead to serious complications. We have developed a three-dimensional (3D) transrectal US system and are investigating its use for intra-operative visualization of needle positions used in HDR gynaecological brachytherapy. As a proof-of-concept, four patients were imaged with post-insertion 3D US and x-ray CT. Using software developed in our laboratory, manual rigid registration of the two modalities was performed based on the perineal template's vaginal cylinder. The needle tip and a second point along the needle path were identified for each needle visible in US. The difference between modalities in the needle trajectory and needle tip position was calculated for each identified needle. For the 60 needles placed, the mean trajectory difference was 3.23 +/- 1.65° across the 53 visible needle paths and the mean difference in needle tip position was 3.89 +/- 1.92 mm across the 48 visible needles tips. Based on the preliminary results, 3D transrectal US shows potential for the development of a 3D US-based needle guidance system for interstitial gynaecological brachytherapy.

  14. Sci—Thur AM: YIS - 11: Estimation of Bladder-Wall Cumulative Dose in Multi-Fraction Image-Based Gynaecological Brachytherapy Using Deformable Point Set Registration

    Energy Technology Data Exchange (ETDEWEB)

    Zakariaee, R [Physics Department, University of British Columbia, Vancouver, BC (Canada); Brown, C J; Hamarneh, G [School of Computing Science, Simon Fraser University, Burnaby, BC (Canada); Parsons, C A; Spadinger, I [British Columbia Cancer Agency, Vancouver, BC (Canada)

    2014-08-15

    Dosimetric parameters based on dose-volume histograms (DVH) of contoured structures are routinely used to evaluate dose delivered to target structures and organs at risk. However, the DVH provides no information on the spatial distribution of the dose in situations of repeated fractions with changes in organ shape or size. The aim of this research was to develop methods to more accurately determine geometrically localized, cumulative dose to the bladder wall in intracavitary brachytherapy for cervical cancer. The CT scans and treatment plans of 20 cervical cancer patients were used. Each patient was treated with five high-dose-rate (HDR) brachytherapy fractions of 600cGy prescribed dose. The bladder inner and outer surfaces were delineated using MIM Maestro software (MIM Software Inc.) and were imported into MATLAB (MathWorks) as 3-dimensional point clouds constituting the “bladder wall”. A point-set registration toolbox for MATLAB, Coherent Point Drift (CPD), was used to non-rigidly transform the bladder-wall points from four of the fractions to the coordinate system of the remaining (reference) fraction, which was chosen to be the emptiest bladder for each patient. The doses were accumulated on the reference fraction and new cumulative dosimetric parameters were calculated. The LENT-SOMA toxicity scores of these patients were studied against the cumulative dose parameters. Based on this study, there was no significant correlation between the toxicity scores and the determined cumulative dose parameters.

  15. Sci—Thur AM: YIS - 11: Estimation of Bladder-Wall Cumulative Dose in Multi-Fraction Image-Based Gynaecological Brachytherapy Using Deformable Point Set Registration

    International Nuclear Information System (INIS)

    Dosimetric parameters based on dose-volume histograms (DVH) of contoured structures are routinely used to evaluate dose delivered to target structures and organs at risk. However, the DVH provides no information on the spatial distribution of the dose in situations of repeated fractions with changes in organ shape or size. The aim of this research was to develop methods to more accurately determine geometrically localized, cumulative dose to the bladder wall in intracavitary brachytherapy for cervical cancer. The CT scans and treatment plans of 20 cervical cancer patients were used. Each patient was treated with five high-dose-rate (HDR) brachytherapy fractions of 600cGy prescribed dose. The bladder inner and outer surfaces were delineated using MIM Maestro software (MIM Software Inc.) and were imported into MATLAB (MathWorks) as 3-dimensional point clouds constituting the “bladder wall”. A point-set registration toolbox for MATLAB, Coherent Point Drift (CPD), was used to non-rigidly transform the bladder-wall points from four of the fractions to the coordinate system of the remaining (reference) fraction, which was chosen to be the emptiest bladder for each patient. The doses were accumulated on the reference fraction and new cumulative dosimetric parameters were calculated. The LENT-SOMA toxicity scores of these patients were studied against the cumulative dose parameters. Based on this study, there was no significant correlation between the toxicity scores and the determined cumulative dose parameters

  16. Re-distribution of brachytherapy dose using a differential dose prescription adapted to risk of local failure in low-risk prostate cancer patients

    DEFF Research Database (Denmark)

    Rylander, Susanne; Polders, Daniel; Steggerda, Marcel J; Moonen, Luc M; Tanderup, Kari; Van der Heide, Uulke A

    2015-01-01

    BACKGROUND AND PURPOSE: We investigated the application of a differential target- and dose prescription concept for low-dose-rate prostate brachytherapy (LDR-BT), involving a re-distribution of dose according to risk of local failure and treatment-related morbidity. MATERIAL AND METHODS: Our study...

  17. Calculational Tool for Skin Contamination Dose Assessment

    CERN Document Server

    Hill, R L

    2002-01-01

    Spreadsheet calculational tool was developed to automate the calculations preformed for dose assessment of skin contamination. This document reports on the design and testing of the spreadsheet calculational tool.

  18. Assessment of ocular beta radiation dose distribution due to 106Ru/106Rh brachytherapy applicators using MCNPX Monte Carlo code

    Directory of Open Access Journals (Sweden)

    Nilseia Aparecida Barbosa

    2014-08-01

    Full Text Available Purpose: Melanoma at the choroid region is the most common primary cancer that affects the eye in adult patients. Concave ophthalmic applicators with 106Ru/106Rh beta sources are the more used for treatment of these eye lesions, mainly lesions with small and medium dimensions. The available treatment planning system for 106Ru applicators is based on dose distributions on a homogeneous water sphere eye model, resulting in a lack of data in the literature of dose distributions in the eye radiosensitive structures, information that may be crucial to improve the treatment planning process, aiming the maintenance of visual acuity. Methods: The Monte Carlo code MCNPX was used to calculate the dose distribution in a complete mathematical model of the human eye containing a choroid melanoma; considering the eye actual dimensions and its various component structures, due to an ophthalmic brachytherapy treatment, using 106Ru/106Rh beta-ray sources. Two possibilities were analyzed; a simple water eye and a heterogeneous eye considering all its structures. Two concave applicators, CCA and CCB manufactured by BEBIG and a complete mathematical model of the human eye were modeled using the MCNPX code. Results and Conclusion: For both eye models, namely water model and heterogeneous model, mean dose values simulated for the same eye regions are, in general, very similar, excepting for regions very distant from the applicator, where mean dose values are very low, uncertainties are higher and relative differences may reach 20.4%. For the tumor base and the eye structures closest to the applicator, such as sclera, choroid and retina, the maximum difference observed was 4%, presenting the heterogeneous model higher mean dose values. For the other eye regions, the higher doses were obtained when the homogeneous water eye model is taken into consideration. Mean dose distributions determined for the homogeneous water eye model are similar to those obtained for the

  19. Tank Z-361 dose rate calculations

    International Nuclear Information System (INIS)

    Neutron and gamma ray dose rates were calculated above and around the 6-inch riser of tank Z-361 located at the Plutonium Finishing Plant. Dose rates were also determined off of one side of the tank. The largest dose rate 0.029 mrem/h was a gamma ray dose and occurred 76.2 cm (30 in.) directly above the open riser. All other dose rates were negligible. The ANSI/ANS 1991 flux to dose conversion factor for neutrons and photons were used in this analysis. Dose rates are reported in units of mrem/h with the calculated uncertainty shown within the parentheses

  20. Cosmetic results in early stage breast cancer patients with high-dose brachytherapy after conservative surgery

    International Nuclear Information System (INIS)

    Purpose: to reveal cosmetic results in patients at early stages of low risk breast cancer treated with partial accelerated radiotherapy using high dose rate brachytherapy. Methods and materials: from March 2001 to July 2003,14 stages l and ll breast cancer patients were treated at the Colombian national cancer institute in Bogota with conservative surgery and radiotherapy upon the tumor bed (partial accelerated radiotherapy), using interstitial implants with iridium 192 (high dose rate brachytherapy) with a dose of 32 Gys, over 4 days, at 8 fractions twice a day. Results: with an average follow up of 17.7 months, good cosmetic results were found among 71.4 % of patients and excellent results among 14.3% of patients, furthermore none of the patients neither local nor regional or distant relapses. Conclusion: among patients who suffer from breast cancer at early stages, it showed is possible to apply partial accelerated radiotherapy upon the tumor bed with high doses over 4 days with good to excellent cosmetic results

  1. Reduction of rectal doses by removal of gas in the rectum during vaginal cuff brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Sabater, S.; Sevillano, M.M.; Andres, I.; Berenguer, R. [Complejo Hospitalario Univ. de Albacete (CHUA) (Spain). Dept. of Radiation Oncology; Machin-Hamalainen, S. [C.S. General Ricardos, Madrid (Spain); Mueller, K.; Arenas, M. [Hospital Univ. Sant Joan, Reus (Spain). Dept. of Radiation Oncology

    2013-11-15

    Objective: The goal of this work was to evaluate whether the volume reduction related to removal of gas in the rectum could be translated in lower doses to organs at risk (OAR) during vaginal cuff brachytherapy (VBT). Material and methods: Fourteen pairs of brachytherapy planning CT scans derived from 11 patients were re-segmented and re-planned using the same parameters. The only difference between pairs of CTs was the presence or lack of gas in the rectum. The first CT showed the basal status and the second was carried out after gas removal with a tube. A set of values derived from bladder and rectum dose-volume histograms (DVH) and dose-surface histograms (DSH) were extracted. Moreover the cylinder position related to the patient craniocaudal axis was recorded. Results: Rectum volume decreased significantly from 77.8 {+-} 45 to 55.43 {+-} 17.6 ml (p = 0.0052) after gas removal. Such volume diminution represented a significant reduction on all rectal DVH parameters analyzed except D{sub 25%} and D{sub 50%}. DSH parameter results were similar to previous ones. A nonsignificant increase of the bladder volume was observed and was associated with an increase of the DVH metrics analyzed. Conclusion: Removal of gas pockets is a simple and inexpensive maneuver that decreases rectal dose parameters on VBT, which can be translated as a better therapeutic ratio. It also suggests that other actions directed to empty the rectum could have a similar effect. (orig.)

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

    International Nuclear Information System (INIS)

    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)

  3. Experiences of high dose rate interstitial brachytherapy for carcinoma of the mobile tongue

    International Nuclear Information System (INIS)

    Interstitial brachytherapy was conducted for mobile tongue carcinoma using a high dose rate remote afterloading machine with small 192I source. Detailed method, named as 'linked double-botton technique', is to approach from submandibular skin by an open-ended stainless steel needles to the tongue lesion, and to replace each needle into flexible nylon tube from the oral cavity. Delivered dose was 60 Gy/10 Fr./5-6 days at the distance 5 mm from the source plane. Ten patients with mobile tongue carcinoma Tl-2N0 were treated with this method from October 1991 through August 1992. Local was uncontrolled in one patient, in whom the lesion was combined with leukoplakia at both lateral borders of the tongue. This was in accordance with the result in low dose rate treatment. This can be a substitute to low dose rate system for treatment of mobile tongue carcinoma. (author)

  4. High-dose-rate brachytherapy using molds for lip and oral cavity tumors

    International Nuclear Information System (INIS)

    High-dose-rate (HDR) brachytherapy using the mold technique is a less invasive treatment for early lip and oral cavity cancer. However, limited reports exist regarding the feasibility of this method. In this retrospective study, we evaluated the outcome of this therapy and investigated its feasibility for lip and oral cavity tumors. Between May 2002 and December 2010, 17 patients (median age, 80.0 years) with histologically confirmed squamous cell carcinoma of the lip or oral cavity were treated by means of HDR brachytherapy using the mold technique after external beam radiotherapy (EBRT). Tumor sites included the buccal mucosa in eight cases, the gingiva in three cases, the lips in two cases, the floor of the mouth in two cases, and the hard palate in two cases. For all patients, EBRT (30 Gy/15 fractions), was performed before HDR brachytherapy. Two 6-Gy fractions were delivered twice daily for 2 days a week with an interval of 6 hours between the fractions. The total HDR brachytherapy dose was 24 Gy. Prior to EBRT, two patients with neck metastasis underwent neck dissection, and one patient with an exophytic tumor underwent tumor resection. The median follow-up period was 53.4 (range, 4.8–83.4) months. Of the 17 patients, 14 (82.4%) achieved a complete response, and three (17.6%) displayed a partial response. The overall 3- and 5-year survival rates were both 68.8%, the 3- and 5-year disease-specific survival rates were both 86.7%, and the 3- and 5-year local control rates were both 54.1%. Seven patients developed local recurrence at a median time of 3.4 (range, 1.7–29.1) months after treatment. Nodal and lung metastases occurred separately in two patients. By the end of the follow-up period, two patients had died of the primary disease and four patients had died of other causes. Although there is a need to improve the technical aspects of the treatment protocol, HDR brachytherapy using the mold technique might be a therapeutic option for superficial lip or

  5. Nerve tolerance to high-dose-rate brachytherapy in patients with soft tissue sarcoma: a retrospective study

    International Nuclear Information System (INIS)

    Brachytherapy, interstitial tumor bed irradiation, following conservative surgery has been shown to provide excellent local control and limb preservation in patients with soft tissue sarcomas (STS), whereas little is known about the tolerance of peripheral nerves to brachytherapy. In particular, nerve tolerance to high-dose-rate (HDR) brachytherapy has never been properly evaluated. In this study, we examined the efficacy and radiation neurotoxicity of HDR brachytherapy in patients with STS in contact with neurovascular structures. Between 1995 and 2000, seven patients with STS involving the neurovascular bundle were treated in our institute with limb-preserving surgery, followed by fractionated HDR brachytherapy. Pathological examination demonstrated that 6 patients had high-grade lesions with five cases of negative margins and one case with positive margins, and one patient had a low-grade lesion with a negative margin. Afterloading catheters placed within the tumor bed directly upon the preserved neurovascular structures were postoperatively loaded with Iridium-192 with a total dose of 50 Gy in 6 patients. One patient received 30 Gy of HDR brachytherapy combined with 20 Gy of adjuvant external beam radiation. With a median follow-up of 4 years, the 5-year actuarial overall survival, disease-free survival, and local control rates were 83.3, 68.6, and 83.3%, respectively. None of the 7 patients developed HDR brachytherapy-induced peripheral neuropathy. Of 5 survivors, 3 evaluable patients had values of motor nerve conduction velocity of the preserved peripheral nerve in the normal range. In this study, there were no practical and electrophysiological findings of neurotoxicity of HDR brachytherapy. Despite the small number of patients, our encouraging results are valuable for limb-preserving surgery of unmanageable STS involving critical neurovascular structures

  6. Fast radioactive seed localization in intraoperative cone beam CT for low-dose-rate prostate brachytherapy

    Science.gov (United States)

    Hu, Yu-chi; Xiong, Jian-ping; Cohan, Gilad; Zaider, Marco; Mageras, Gig; Zelefsky, Michael

    2013-03-01

    A fast knowledge-based radioactive seed localization method for brachytherapy was developed to automatically localize radioactive seeds in an intraoperative volumetric cone beam CT (CBCT) so that corrections, if needed, can be made during prostate implant surgery. A transrectal ultrasound (TRUS) scan is acquired for intraoperative treatment planning. Planned seed positions are transferred to intraoperative CBCT following TRUS-to-CBCT registration using a reference CBCT scan of the TRUS probe as a template, in which the probe and its external fiducial markers are pre-segmented and their positions in TRUS are known. The transferred planned seeds and probe serve as an atlas to reduce the search space in CBCT. Candidate seed voxels are identified based on image intensity. Regions are grown from candidate voxels and overlay regions are merged. Region volume and intensity variance is checked against known seed volume and intensity profile. Regions meeting the above criteria are flagged as detected seeds; otherwise they are flagged as likely seeds and sorted by a score that is based on volume, intensity profile and distance to the closest planned seed. A graphical interface allows users to review and accept or reject likely seeds. Likely seeds with approximately twice the seed volume are automatically split. Five clinical cases are tested. Without any manual correction in seed detection, the method performed the localization in 5 seconds (excluding registration time) for a CBCT scan with 512×512×192 voxels. The average precision rate per case is 99% and the recall rate is 96% for a total of 416 seeds. All false negative seeds are found with 15 in likely seeds and 1 included in a detected seed. With the new method, updating of calculations of dose distribution during the procedure is possible and thus facilitating evaluation and improvement of treatment quality.

  7. Prostate brachytherapy

    Science.gov (United States)

    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. MRI-assisted treatment planning in brachytherapy of cervical- and endometrial-Ca: dose to organs at risk

    International Nuclear Information System (INIS)

    Dose to organs at risk in brachytherapy of cervical and endometrial cancer is measured directly in the rectum and urinary bladder during irradiation, e.g. by semiconductors or estimated by reference points (ICRU 38). MRI gives excellent information of anatomical relation between treatment volume and organs at risk. Methods: 8 Patients with cervical and 4 patients with endometrial carcinoma underwent MRI of the pelvis with in-situ applicators (ring-/tandem-applicators for cervical-Ca and Heyman-Capsules for endometrial-Ca). Dose prescription was 8.5 Gy to Pt. A in cervical-Ca resp. 10 Gy to point 'My' in endometrial-Ca. T1w slices were angulated twice (coronal and sagittal) to get rectangular reproductions to applicator axis. The coordinates of dorsal bladder wall, ventral rectum wall and small intestine closest to the applicator were measured. The dose to these points, e.g. maximum doses, was calculated with the aid of the Nucletron Treatment Planning System 'Plato'. Target and organs at risk were contourated and dose-volume-histograms were calculated. Results: The maximum dose to the dorsal bladder wall was 10.35 Gy/fx at mean in cervical- and 6.67 Gy/fx in endometrial-carcinoma. The mean of max.-dose in ICRU reference point was calculated at 5.4 Gy/fx (cerv.ca) and 5.1 Gy/fx (endom. ca), a difference of 52 % resp. 34 %. Mean irradiated bladder wall volume at 7 Gy isodose was 2.9 ccm in cervical- and 5 ccm in endometrial-Ca. The mean of the maximum dose to the ventral rectum wall was 8.5 Gy/fx (MRI) vs. 5.1 Gy/fx (ICRU-point) in cervical-Ca and 10.34 Gy/fx (MRI) vs 2.4 Gy/fx at ICRU-point in endometrial-Ca, a difference of 41 % resp. 430 %. The irradiated volume at 7 Gy isodose was smaller than 1ccm in both entities. The dose and volume to small intestine was neglectable in most patients, however for 1 patient the 7 Gy isodose included 6 ccm of small intestine. Conclusion: MRI gives excellent information in order to calculate the dose-volume relationship. In some

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

    International Nuclear Information System (INIS)

    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

  10. Brachytherapy applications and techniques

    CERN Document Server

    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

  11. High-dose-rate-intracavitary brachytherapy applications and the difference in the bladder and rectum doses: A study from rural centre of Maharashatra, India

    Directory of Open Access Journals (Sweden)

    Jain Vandana

    2007-01-01

    Full Text Available Aim : To report the difference in the bladder and rectum doses with different applications by the radiotherapists in the same patient of the carcinoma of the uterine cervix treated by multiple fractions of high-dose-rate (HDR intracavitary brachytherapy (ICBT. Materials and Methods : Between January 2003 to December 2004, a total of 60 cases of the carcinoma uterine cervix were selected randomly for the retrospective analyses. All 60 cases were grouped in six groups according to the treating radiotherapist who did the HDR-ICBT application. Three radiotherapists were considered for this study, named A, B and C. Ten cases for each radiotherapist in whom all three applications were done by the same radiotherapist. And 10 cases for each radiotherapist with shared applications in the same patient (A+B, A+C and B+C. The bladder and rectal doses were calculated in reference to point "A" dose and were limited to 80% of prescribed point "A" dose, as per ICRU-38 recommendations. Received dose grouped in three groups- less then 80% (< 80%, 80-100% and above 100% (>100%. A total of 180 applications for 60 patients were calculated for the above analyses. Results : There is a lot of difference in the bladder and rectal doses with the application by the different radiotherapists, even in the same patient with multiple fractions of HDR-ICBT. Applications by ′A′ radiotherapist were within the limits in the self as well as in the shared groups more number of times, by ′B′ radiotherapist was more times exceeding the limit and by ′C′ radiotherapist doses were in between the A and B. Discussion and Conclusion : For the rectal and bladder doses most important factors are patient′s age, disease stage, duration between EBRT and HDR-ICRT and patient anatomy, but these differences can be minimized to some extent by careful application, proper packing and proper fixation.

  12. Factors for Predicting Rectal Dose of High-Dose-Rate Intracavitary Brachytherapy After Pelvic Irradiation in Patients With Cervical Cancer: A Retrospective Study With Radiography-Based Dosimetry

    International Nuclear Information System (INIS)

    Purpose: To evaluate the predictive factors for rectal dose of the first fraction of high-dose-rate intracavitary brachytherapy (HDR-ICBT) in patients with cervical cancer. Methods and Materials: From March 1993 through February 2008, 946 patients undergoing pelvic irradiation and HDR-ICBT were analyzed. Examination under anesthesia (EUA) at the first implantation of the applicator was usually performed in the early period. Rectal point was determined radiographically according to the 38th Report of the International Commission of Radiation Units and Measurements (ICRU). The ICRU rectal dose (PRD) as a percentage of point A dose was calculated; multiple linear regression models were used to predict PRD. Results: Factors influencing successful rectal dose calculation were EUA (p < 0.001) and absence of diabetes (p = 0.047). Age (p < 0.001), body weight (p = 0.002), diabetes (p = 0.020), and EUA (p < 0.001) were independent factors for the PRD. The predictive equation derived from the regression model was PRD (%) = 57.002 + 0.443 x age (years) - 0.257 x body weight (kg) + 6.028 x diabetes (no: 0; yes: 1) - 8.325 x EUA (no: 0; yes: 1) Conclusion: Rectal dose at the first fraction of HDR-ICBT is positively influenced by age and diabetes, and negatively correlated with EUA and body weight. A small fraction size at point A may be considered in patients with a potentially high rectal dose to reduce the biologically effective dose if the ICRU rectal dose has not been immediately obtained in the first fraction of HDR-ICBT.

  13. Comparison of methods for the measurement of radiation dose distributions in high dose rate (HDR) brachytherapy: Ge-doped optical fiber, EBT3 Gafchromic film, and PRESAGE® radiochromic plastic

    International Nuclear Information System (INIS)

    Purpose: Dose distribution measurement in clinical high dose rate (HDR) brachytherapy is challenging, because of the high dose gradients, large dose variations, and small scale, but it is essential to verify accurate treatment planning and treatment equipment performance. The authors compare and evaluate three dosimetry systems for potential use in brachytherapy dose distribution measurement: Ge-doped optical fibers, EBT3 Gafchromic film with multichannel analysis, and the radiochromic material PRESAGE® with optical-CT readout. Methods: Ge-doped SiO2 fibers with 6 μm active core and 5.0 mm length were sensitivity-batched and their thermoluminescent properties used via conventional heating and annealing cycles. EBT3 Gafchromic film of 30 μm active thickness was calibrated in three color channels using a nominal 6 MV linear accelerator. A 48-bit transmission scanner and advanced multichannel analysis method were utilized to derive dose measurements. Samples of the solid radiochromic polymer PRESAGE®, 60 mm diameter and 100 mm height, were analyzed with a parallel beam optical CT scanner. Each dosimetry system was used to measure the dose as a function of radial distance from a Co-60 HDR source, with results compared to Monte Carlo TG-43 model data. Each system was then used to measure the dose distribution along one or more lines through typical clinical dose distributions for cervix brachytherapy, with results compared to treatment planning system (TPS) calculations. Purpose-designed test objects constructed of Solid Water and held within a full-scatter water tank were utilized. Results: All three dosimetry systems reproduced the general shape of the isolated source radial dose function and the TPS dose distribution. However, the dynamic range of EBT3 exceeded those of doped optical fibers and PRESAGE®, and the latter two suffered from unacceptable noise and artifact. For the experimental conditions used in this study, the useful range from an isolated HDR

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

    International Nuclear Information System (INIS)

    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)

  15. High-dose-rate brachytherapy in the treatment of uterine cervix cancer. Analysis of dose effectiveness and late complications

    International Nuclear Information System (INIS)

    Purpose: This retrospective analysis aims to report results of patients with cervix cancer treated by external beam radiotherapy (EBR) and high-dose-rate (HDR) brachytherapy. Methods and Materials: From September 1992 to December 1996, 138 patients with FIGO Stages II and III and mean age of 56 years were treated. Median EBR to the whole pelvis was 45 Gy in 25 fractions. Parametrial boost was performed in 93% of patients, with a median dose of 14.4 Gy. Brachytherapy with HDR was performed during EBR or following its completion with a dose of 24 Gy in four weekly fractions of 6 Gy to point A. Median overall treatment time was of 60 days. Patient age, tumor stage, and overall treatment time were variables analyzed for survival and local control. Cumulative biologic effective dose (BED) at rectal and bladder reference points were correlated with late complications in these organs and dose of EBR at parametrium was correlated with small bowel complications. Results: Median follow-up time was 38 months. Overall survival, disease-free survival, and local control at 5 years was 53.7%, 52.7%, and 62%, respectively. By multivariate and univariate analysis, overall treatment time up to 50 days was the only statistically significant adverse variable for overall survival (p=0.003) and actuarial local control (p=0.008). The 5-year actuarial incidence of rectal, bladder, and small bowel late complications was 16%, 11%, and 14%, respectively. Patients treated with cumulative BED at rectum points above 110 Gy3 and at bladder point above 125 Gy3 had a higher but not statistically significant 5-year actuarial rate of complications at these organs (18% vs. 12%, p=0.49 and 17% vs. 9%, p=0.20, respectively). Patients who received parametrial doses larger than 59 Gy had a higher 5-year actuarial rate of complications in the small bowel; however, this was not statistically significant (19% vs. 10%, p=0.260). Conclusion: This series suggests that 45 Gy to the whole pelvis combined with

  16. Dose verification in HDR brachytherapy and IMRT with Fricke gel-layer dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Negri, A.; Bartesaghi, G.; Pirola, L. [Department of Physics, Universita degli Studi di Milano, Italy (Italy); Carrara, M.; Gambini, I.; Tomatis, S.; Fallai, C.; Zonca, G. [Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy (Italy); Stokucova, J. [Faculty Hospital Na Bulovce, Prague, Czech Republic (Czech Republic)

    2009-10-15

    At the Department of Physics of the Universita degli Studi di Milano in collaboration with the Medical Physics Unit and the Radiotherapy Unit of the Fondazione IRCCS Istituto Nazionale dei Tumori di Milano the research of a dosimetric technique based on Fricke gel layers and optical analysis in under study. In fact, Fricke gel layer dosimeters (FGLD) have various advantages such as the tissue-equivalence for photons in the clinical energy interval, the possibility to obtain the spatial information about continuous dose distribution and not only a point dose distribution as it is for example in the case of ionization chambers, TLD or diodes and the possibility to obtain the information about 3D dose distributions. In this work, specific applications of FGLD to absolute dosimetry in radiotherapy have been studied, i.e. in-phantom measurements of complex intensity modulated radiation therapy fields (IMRT) and complex brachytherapy fields. (Author)

  17. Phase II investigation: partial breast irradiation with high-dose brachytherapy using intratissue multicatheter implant

    International Nuclear Information System (INIS)

    Local control, side-effects, and cosmetic results were analyzed in patients with early-stage breast cancer after organpreserving surgery and adjuvant partial accelerated irradiation of the breast using high dose rate brachytherapy and intratissue multicatheter implant. The patients over 50 with solitary tumors < 3 cm invasive ductal carcinoma, differentiation grade I-III, resection R0, N0 (axillary dissection or investigation of signal lymph node) were included in the study. The irradiation was performed twice a day with a 6-hour interval at a single dose of 4 Gy. Total focal dose of 32 Gy was delivered with 8 fractions. With a mean observation period of 31 months (13-46), a local relapse was diagnosed in one patient (1.7 %). Cosmetic results were assessed as good and excellent. Immediate complications of the treatment were minimal. The method can be indicated in a selected group of patients and cannot be a standard of treatment at present.

  18. Dose verification in HDR brachytherapy and IMRT with Fricke gel-layer dosimeters

    International Nuclear Information System (INIS)

    At the Department of Physics of the Universita degli Studi di Milano in collaboration with the Medical Physics Unit and the Radiotherapy Unit of the Fondazione IRCCS Istituto Nazionale dei Tumori di Milano the research of a dosimetric technique based on Fricke gel layers and optical analysis in under study. In fact, Fricke gel layer dosimeters (FGLD) have various advantages such as the tissue-equivalence for photons in the clinical energy interval, the possibility to obtain the spatial information about continuous dose distribution and not only a point dose distribution as it is for example in the case of ionization chambers, TLD or diodes and the possibility to obtain the information about 3D dose distributions. In this work, specific applications of FGLD to absolute dosimetry in radiotherapy have been studied, i.e. in-phantom measurements of complex intensity modulated radiation therapy fields (IMRT) and complex brachytherapy fields. (Author)

  19. Interstitial high-dose-rate brachytherapy in locally advanced and recurrent vulvar cancer

    Science.gov (United States)

    Białas, Brygida; Fijałkowski, Marek; Wojcieszek, Piotr; Szlag, Marta; Cholewka, Agnieszka; Ślęczka, Maciej; Kołosza, Zofia

    2016-01-01

    Purpose The aim of the study was to report our experience with high-dose-rate interstitial brachytherapy (HDR-ISBT) in locally advanced and recurrent vulvar cancer. Material and methods Between 2004 and 2014, fourteen women with locally advanced or recurrent vulvar cancer were treated using HDR-ISBT in our Centre. High-dose-rate interstitial brachytherapy was performed as a separate treatment or in combination with external beam radiotherapy (EBRT) (given prior to brachytherapy). Results Patients were divided into: group I (n = 6) with locally advanced tumors, stages III-IVA after an incisional biopsy only, and group II (n = 8) with recurrent vulvar cancer after previous radical surgery. In group I, median follow up was 12 months (range 7-18 months); 1-year overall survival (OS) was 83%. Transient arrest of cancer growth or tumor regression was noticed in all patients but 4/6 developed relapse. Median time to failure was 6.3 months (range 3-11 months). The 1-year progression-free survival (PFS) was 33%. In group II, median follow up was 28 months (range 13-90 months). The 1-year and 3-year OS was 100% and 80%, respectively. The arrest of cancer growth or tumor regression was achieved in all patients. In 4/8 patients neither clinical nor histological symptoms of relapse were observed but 4/8 women experienced relapse. Median time to failure was 31 months (range 13-76 months). The 1-year and 3-year PFS was 100% and 62.5%, respectively. Two patients (14.3%) in group II had severe late toxicity (G3). Conclusions High-dose-rate interstitial brachytherapy is a well-tolerated treatment option in selected patients with advanced or recurrent vulvar cancer. It is a safe and effective treatment modality for advanced and recurrent vulvar cancer, yielding good local control with acceptable late treatment related side effects. In our study, patients with recurrent vulvar cancer had better results in HDR-ISBT treatment, probably because of the smaller tumor volume. This

  20. Determination of the accuracy of implant reconstruction and dose delivery in brachytherapy in The Netherlands and Belgium

    International Nuclear Information System (INIS)

    Purpose: To gain insight into the accuracy of brachytherapy treatments, the accuracy of implant reconstruction and dose delivery was investigated in 33 radiotherapy institutions in The Netherlands and Belgium. Materials and methods: The accuracy of the implant reconstruction method was determined using a cubic phantom containing 25 spheres at well-known positions. Reconstruction measurements were obtained on 41 brachytherapy localizers, 33 of which were simulators. The reconstructed distances between the spheres were compared with the true distances. The accuracy of the dose delivery was determined for high dose rate (HDR), pulsed dose rate (PDR) and low dose rate (LDR) afterloading systems using a polymethyl methacrylate cylindrical phantom containing a NE 2571 ionization chamber in its centre. The institutions were asked to deliver a prescribed dose at the centre of the phantom. The measured dose was compared with the prescribed dose. Results: The average reconstruction accuracy was -0.07 mm (±0.4 mm, 1 SD) for 41 localizers. The average deviation of the measured dose from the prescribed dose was +0.9% (±1.3%, 1 SD) for 21 HDR afterloading systems, +1.0% (±2.3%, 1 SD) for 12 PDR afterloaders, and +1.8% (±2.5%, 1 SD) for 15 LDR afterloaders. Conclusions: This comparison showed a good accuracy of brachytherapy implant reconstruction and dose delivery in The Netherlands and Belgium

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

    Science.gov (United States)

    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

  2. High dose rate brachytherapy for carcinoma of the oral tongue

    International Nuclear Information System (INIS)

    Purpose: The purpose of this study is to assess the feasibility of treating early-staged tongue cancer with high dose rate (HDR) remote afterloading technique. Furthermore, a new figure of merit, the Geometry Index (GI), is introduced to quantify the quality of the implants. Methods and Materials: Between 1994 and 1995, eight patients with carcinoma of the oral tongue were treated solely with interstitial implant using the HDR remote afterloading technique. Five patients had T1 NO disease and the remaining three had T2 N0 disease. Elective neck treatment was withheld. The male-to-female ratio was 1:1, and the mean age 60 years (range: 32-72 years). The median follow-up time was 26 months (range: 6-30 months). The afterloading catheters were positioned through the submandibular approach with the assistance of templates. Six patients had single planar implant and the remaining two had double planar implant. The median number of catheters inserted was 5 (range: 4-9). The median dose given was 60 Gy in 10 fractions over 6 days. The interfraction interval was 7 h. Mandibular and maxillary shields were inserted prior to treatment. Thomadsen et al. introduced the use of Implant Quality Index (QI). We introduce a new parameter, GI, which is defined as ratio of the QI of the nonoptimized executed implant to the corresponding QI value of the nonoptimized idealized implant. Results: The mucositis lasted for 6 to 20 weeks (median: 10 weeks). There was no local failure up to a median follow-up of 26 months. Two patients developed ipsilateral neck node metastases at 2 and 4 months following implant, respectively. One patient had involvement at level II and the other failed at level I to III. Both patients were salvaged by neck node dissection and regionally remained in control. One patient with multiple nodal metastases and extracapsular spread developed biopsy-proven liver metastases and succumbed 6 months following implant. One patient treated with double planar implant

  3. Effect of Bladder Distension on Dose Distribution of Intracavitary Brachytherapy for Cervical Cancer: Three-Dimensional Computed Tomography Plan Evaluation

    International Nuclear Information System (INIS)

    Purpose: To quantify the effect of bladder volume on the dose distribution during intracavitary brachytherapy for cervical cancer. Methods and Patients: The study was performed on 10 women with cervical cancer who underwent brachytherapy treatment. After insertion of the brachytherapy applicator, the patients were transferred to the computed tomography unit. Two sets of computed tomography slices were taken, including the pelvis, one with an empty bladder and one after the bladder was filled with saline. The target and critical organs were delineated by the radiation oncologist and checked by the expert radiologist. The radiotherapy plan was run on the Plato planning system, version 14.1, to determine the dose distributions, dose-volume histograms, and maximal dose points. The doses and organ volumes were compared with the Wilcoxon signed ranks test on a personal computer using the Statistical Package for Social Sciences, version 11.0, statistical program. Results: No significant difference regarding the dose distribution and target volumes between an empty or full bladder was observed. Bladder fullness significantly affected the dose to the small intestine, rectum, and bladder. The median of maximal doses to the small intestine was significantly greater with an empty bladder (493 vs. 284 cGy). Although dosimetry revealed lower doses for larger volumes of bladder, the median maximal dose to the bladder was significantly greater with a full bladder (993 vs. 925 cGy). The rectal doses were also affected by bladder distension. The median maximal dose was significantly lower in the distended bladder (481vs. 628 cGy). Conclusions: Bladder fullness changed the dose distributions to the bladder, rectum, and small intestine. The clinical importance of these changes is not known and an increase in the use of three-dimensional brachytherapy planning will highlight the answer to this question

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    International Nuclear Information System (INIS)

    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

  6. Perioperative fractionated high dose rate brachytherapy in bone and soft-tissue tumors

    International Nuclear Information System (INIS)

    Purpose/Objective: Perioperative fractionated HDR brachytherapy was applied for treatment of bone and soft-tissue tumors. We investigate the local control and side effect, and consider possibility to reduce surgical margin. Materials and Methods: The 13 lesions of 11 patients with bone and soft-tissue tumors (four primary and nine recurrent lesions) were treated at Osaka University Hospital between Aug. 1992 and Feb. 1995. Follow-up terms are between a year and 30 months (median; 15 months). They consisted of 8 males and 3 females. The age ranged from 14 to 75 (median; 38). The histology contained 3 MFH's, 2 liposarcomas, 1 chordoma, osteosarcoma, malignant schwanoma, synovial sarcoma, and epithelioid sarcoma. The sites of lesion are 4 pelvis, 4 neck or supraclavicle, 3 upper limbs, and 2 lower limbs. The surgical margins including intraoperative catheterizing are 3 wide, 6 marginal, and 4 intralesional resection. Postoperative fractionated high dose rate (HDR) brachytherapy started on 4-7th day after surgery. A total dose was 40-50 Gy/7-10 fr/6-7 d (bid) at 5 mm from the sources. Results: One case was dead of tumor, 4 cases were dead of metastasis, 1 case is alive with tumor, 2 cases are alive with distant metastasis, and 4 cases are no evidence of disease. Local control was achieved in eight of 13 lesions (62%). Four of the five uncontrolled lesions had macroscopic residual tumor after the surgery. In five of the six marginal resection, lesions were controlled. Local control rates with Kaplan-Mayer methods were 69% in 1 year and 58% in 2 years. Survival rates were 82% in 1 year and 66% in 2 years. There was one peripheral nerve palsy as a side effect. There was no infection or delayed heal of surgical scar, affected by tubing and interstitial radiation. Conclusion: This study indicates that the use of perioperative fractionated HDR brachytherapy is easy, safe, and well tolerated. Some cases with frequent recurrence previously, can also be controlled. A safe

  7. Bladder–Rectum Spacer Balloon in High-Dose-Rate Brachytherapy in Cervix Carcinoma

    International Nuclear Information System (INIS)

    Purpose: To compare bladder and rectum doses with the use of a bladder–rectum spacer balloon (BRSB) versus standard gauze packing in the same patient receiving 2 high-dose-rate intracavitary brachytherapy fractions. Methods and Materials: This was a randomized study to compare the reduction in bladder and rectum doses with the use of a BRSB compared with standard gauze packing in patients with carcinoma of the cervix being treated with high-dose-rate intracavitary brachytherapy. The patients were randomized between 2 arms. In arm A, vaginal packing was done with standard gauze packing in the first application, and BRSB was used in the second application. Arm B was the reverse of arm A. The International Commission for Radiation Units and Measurement (ICRU) point doses and doses to 0.1-cm3, 1-cm3, 2-cm3, 5-cm3, and 10-cm3 volumes of bladder and rectum were compared. The patients were also subjectively assessed for the ease of application and the time taken for application. Statistical analysis was done using the paired t test. Results: A total of 43 patients were enrolled; however, 3 patients had to be excluded because the BRSB could not be inserted owing to unfavorable local anatomy. Thus 40 patients (80 plans) were evaluated. The application was difficult in 3 patients with BRSB, and in 2 patients with BRSB the application time was prolonged. There was no significant difference in bladder doses to 0.1 cm3, 1 cm3, 2 cm3, 5 cm3, and 10 cm3 and ICRU bladder point. Statistically significant dose reductions to 0.1-cm3, 1-cm3, and 2-cm3 volumes for rectum were observed with the BRSB. No significant differences in 5-cm3 and 10-cm3 volumes and ICRU rectum point were observed. Conclusion: A statistically significant dose reduction was observed for small high-dose volumes in rectum with the BRSB. The doses to bladder were comparable for BRSB and gauze packing. Transparent balloons of variable sizes are recommended for patients with a less spacious vaginal cavity

  8. Bladder–Rectum Spacer Balloon in High-Dose-Rate Brachytherapy in Cervix Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Rai, Bhavana [Department of Radiotherapy and Oncology, Regional Cancer Centre, Postgraduate Institute of Medical Education and Research, Chandigarh (India); Patel, Firuza D., E-mail: firuzapatel@gmail.com [Department of Radiotherapy and Oncology, Regional Cancer Centre, Postgraduate Institute of Medical Education and Research, Chandigarh (India); Chakraborty, Santam; Sharma, Suresh C.; Kapoor, Rakesh [Department of Radiotherapy and Oncology, Regional Cancer Centre, Postgraduate Institute of Medical Education and Research, Chandigarh (India); Aprem, Abi Santhosh [Corporate R and D Division, HLL Lifecare Limited, Karamana, Trivandrum (India)

    2013-04-01

    Purpose: To compare bladder and rectum doses with the use of a bladder–rectum spacer balloon (BRSB) versus standard gauze packing in the same patient receiving 2 high-dose-rate intracavitary brachytherapy fractions. Methods and Materials: This was a randomized study to compare the reduction in bladder and rectum doses with the use of a BRSB compared with standard gauze packing in patients with carcinoma of the cervix being treated with high-dose-rate intracavitary brachytherapy. The patients were randomized between 2 arms. In arm A, vaginal packing was done with standard gauze packing in the first application, and BRSB was used in the second application. Arm B was the reverse of arm A. The International Commission for Radiation Units and Measurement (ICRU) point doses and doses to 0.1-cm{sup 3}, 1-cm{sup 3}, 2-cm{sup 3}, 5-cm{sup 3}, and 10-cm{sup 3} volumes of bladder and rectum were compared. The patients were also subjectively assessed for the ease of application and the time taken for application. Statistical analysis was done using the paired t test. Results: A total of 43 patients were enrolled; however, 3 patients had to be excluded because the BRSB could not be inserted owing to unfavorable local anatomy. Thus 40 patients (80 plans) were evaluated. The application was difficult in 3 patients with BRSB, and in 2 patients with BRSB the application time was prolonged. There was no significant difference in bladder doses to 0.1 cm{sup 3}, 1 cm{sup 3}, 2 cm{sup 3}, 5 cm{sup 3}, and 10 cm{sup 3} and ICRU bladder point. Statistically significant dose reductions to 0.1-cm{sup 3}, 1-cm{sup 3}, and 2-cm{sup 3} volumes for rectum were observed with the BRSB. No significant differences in 5-cm{sup 3} and 10-cm{sup 3} volumes and ICRU rectum point were observed. Conclusion: A statistically significant dose reduction was observed for small high-dose volumes in rectum with the BRSB. The doses to bladder were comparable for BRSB and gauze packing. Transparent balloons of

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

    International Nuclear Information System (INIS)

    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

  10. SU-E-J-181: Effect of Prostate Motion On Combined Brachytherapy and External Beam Dose Based On Daily Motion of the Prostate

    Energy Technology Data Exchange (ETDEWEB)

    Narayana, V; McLaughlin, P [Providence Cancer Center, Southfield, MI (United States); University of Michigan, Ann Arbor, MI (United States); Ealbaj, J [University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Purpose: In this study, the adequacy of target expansions on the combined external beam and implant dose was examined based on the measured daily motion of the prostate. Methods: Thirty patients received an I–125 prostate implant prescribed to dose of 90Gy. This was followed by external beam to deliver a dose of 90Gyeq (external beam equivalent) to the prostate over 25 to 30 fractions. An ideal IMRT plan was developed by optimizing the external beam dose based on the delivered implant dose. The implant dose was converted to an equivalent external beam dose using the linear quadratic model. Patients were set up on the treatment table by daily orthogonal imaging and aligning the marker seeds in the prostate. Orthogonal images were obtained at the end of treatment to assess prostate intrafraction motion. Based on the observed motion of the markers between the initial and final images, 5 individual plans showing the actual dose delivered to the patient were calculated. A final true dose distribution was established based on summing the implant dose and the 5 external beam plans. Dose to the prostate, seminal vesicles, lymphnodes and normal tissues, rectal wall, urethra and lower sphincter were calculated and compared to ideal. On 18 patients who were sexually active, dose to the corpus cavernosum and internal pudendal artery was also calculated. Results: The average prostate motion in 3 orthogonal directions was less than 1 mm with a standard deviation of less than +2 mm. Dose and volume parameters showed that there was no decrease in dose to the targets and a marginal decrease in dose to in normal tissues. Conclusion: Dose delivered by seed implant moves with the prostate, decreasing the impact of intrafractions dose movement on actual dose delivered. Combined brachytherapy and external beam dose delivered to the prostate was not sensitive to prostate motion.

  11. Equivalence of Gyn GEC-ESTRO guidelines for image guided cervical brachytherapy with EUD-based dose prescription

    OpenAIRE

    Shaw, William; Rae, William ID; Alber, Markus L

    2013-01-01

    Background To establish a generalized equivalent uniform dose (gEUD) -based prescription method for Image Guided Brachytherapy (IGBT) that reproduces the Gyn GEC-ESTRO WG (GGE) prescription for cervix carcinoma patients on CT images with limited soft tissue resolution. Methods The equivalence of two IGBT planning approaches was investigated in 20 patients who received external beam radiotherapy (EBT) and 5 concomitant high dose rate IGBT treatments. The GGE planning strategy based on dose to ...

  12. Low dose-rate intra-operative brachytherapy for soft tissue sarcomas: 85 cases report

    International Nuclear Information System (INIS)

    MATERIAL AND METHODS: Between May 1986 and January 1994, 85 patients with soft tissue sarcomas underwent intra-operative interstitial implants in conjunction with conservative tumor resections. Brachytherapy was part of the initial treatment in 62 cases, and was realized in 23 cases for recurrent tumor. 70/85 (82%) tumors were located in the limbs, 56/85 (66%) were T2 or T3. 38/85 (45%) were involving or close to neuro-vascular structures. The implant dose was 40 - 65 Gy when brachytherapy was the only treatment 31/85 p), mostly for recurrent sarcomas, and 12 - 25 Gy (mean 20 Gy) when combined with external irradiation ((54(85)) p). RESULTS: Median follow-up is 40 months. - 4 years actuarial survival rate is 70.8% for the whole series, 74.5% for previously untreated patients, 61.8 % for patients treated for recurrent tumors. - 4 years actuarial local control rate is respectively 86.4%, 95; 7% and 68.1%. Of the 8 patients with local relapse, 1 is alive without evolutive disease, 7 have developed pulmonary metastasis. Acute side-effects occurred in 18/85 patients (21 %) requiring surgical repair in 8 cases. Late side-effects were mostly fibrosis (30 p), lymphoedemas (8 p), neuropathies (5 p). As a result, functional impairment was observed in 13/85 (15 %) patients. No amputation was required for side-effects. CONCLUSION: This series emphasizes brachytherapy combined with external irradiation is a safe and efficient treatment technique in the treatment of soft tissue sarcomas. The local control rate appears satisfactory and the side-effects tolerable, with limited functional impairment

  13. Single fraction multimodal image guided focal salvage high-dose-rate brachytherapy for recurrent prostate cancer

    Science.gov (United States)

    Rischke, Hans-Christian; Meyer, Philipp Tobias; Knobe, Sven; Volgeova-Neher, Natalja; Kollefrath, Michael; Jilg, Cordula Annette; Grosu, Anca Ligia; Baltas, Dimos; Kroenig, Malte

    2016-01-01

    Purpose We present a novel method for treatment of locally recurrent prostate cancer (PCa) following radiation therapy: focal, multimodal image guided high-dose-rate (HDR) brachytherapy. Material and methods We treated two patients with recurrent PCa after primary (#1) or adjuvant (#2) external beam radiation therapy. Multiparametric magnetic resonance imaging (mpMRI), choline, positron emission tomography combined with computed tomography (PET/CT), or prostate-specific membrane antigen (PSMA)-PET combined with CT identified a single intraprostatic lesion. Positron emission tomography or magnetic resonance imaging – transrectal ultrasound (MRI-TRUS) fusion guided transperineal biopsy confirmed PCa within each target lesion. We defined a PET and mpMRI based gross tumor volume (GTV). A 5 mm isotropic margin was applied additionally to each lesion to generate a planning target volume (PTV), which accounts for technical fusion inaccuracies. A D90 of 18 Gy was intended in one fraction to each PTV using ultrasound guided HDR brachytherapy. Results Six month follow-up showed adequate prostate specific antygen (PSA) decline in both patients (ΔPSA 83% in patient 1 and ΔPSA 59.3% in patient 2). Follow-up 3-tesla MRI revealed regressive disease in both patients and PSMA-PET/CT showed no evidence of active disease in patient #1. No acute or late toxicities occurred. Conclusions Single fraction, focal, multimodal image guided salvage HDR brachytherapy for recurrent prostate cancer is a feasible therapy for selected patients with single lesions. This approach has to be evaluated in larger clinical trials. PMID:27504134

  14. Perioperative fractionated high-dose rate brachytherapy for malignant bone and soft tissue tumors

    International Nuclear Information System (INIS)

    Purpose: To investigate the viability of perioperative fractionated HDR brachytherapy for malignant bone and soft tissue tumors, analyzing the influence of surgical margin. Methods and Materials: From July 1992 through May 1996, 16 lesions of 14 patients with malignant bone and soft tissue tumors (3 liposarcomas, 3 MFHs, 2 malignant schwannomas, 2 chordomas, 1 osteosarcoma, 1 leiomyosarcoma, 1 epithelioid sarcoma, and 1 synovial sarcoma) were treated at the Osaka University Hospital. The patients' ages ranged from 14 to 72 years (median: 39 years). Treatment sites were the pelvis in 6 lesions, the upper limbs in 5, the neck in 4, and a lower limb in 1. The resection margins were classified as intracapsular in 5 lesions, marginal in 5, and wide in 6. Postoperative fractionated HDR brachytherapy was started on the 4th-13th day after surgery (median: 6th day). The total dose was 40-50 Gy/7-10 fr/ 4-7 day (bid) at 5 or 10 mm from the source. Follow-up periods were between 19 and 46 months (median: 30 months). Results: Local control rates were 75% at 1 year and 48% in 2 years, and ultimate local control was achieved in 8 (50%) of 16 lesions. Of the 8 uncontrolled lesions, 5 (63%) had intracapsular (macroscopically positive) resection margins, and all the 8 controlled lesions (100%) had marginal (microscopically positive) or wide (negative) margins. Of the total, 3 patients died of both tumor and metastasis, 3 of metastasis alone, 1 of tumor alone, and 7 showed no evidence of disease. Peripheral nerve palsy was seen in one case after this procedure, but no infection or delayed wound healing caused by tubing or irradiation has occurred. Conclusion: Perioperative fractionated HDR brachytherapy is safe, well tolerated, and applicable to marginal or wide surgical margin cases

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

    International Nuclear Information System (INIS)

    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

  16. Methods of bone marrow dose calculation

    International Nuclear Information System (INIS)

    Several methods of bone marrow dose calculation for photon irradiation were analised. After a critical analysis, the author proposes the adoption, by the Instituto de Radioprotecao e Dosimetria/CNEN, of Rosenstein's method for dose calculations in Radiodiagnostic examinations and Kramer's method in case of occupational irradiation. It was verified by Eckerman and Simpson that for monoenergetic gamma emitters uniformly distributed within the bone mineral of the skeleton the dose in the bone surface can be several times higher than dose in skeleton. In this way, is also proposed the Calculation of tissue-air ratios for bone surfaces in some irradiation geometries and photon energies to be included in the Rosenstein's method for organ dose calculation in Radiodiagnostic examinations. (Author)

  17. Transperineal low-dose rate iridium-192 interstitial brachytherapy in cervical carcinoma stage IIB

    Energy Technology Data Exchange (ETDEWEB)

    Budrukkar, A.N.; Shrivastava, S.K.; Jalali, R.; Agarwal, J.P.; Dinshaw, K.A. [Tata Memorial Hospital, Parel, Mumbai (India). Dept. of Radiation Oncology; Deshpande, D.D.; Nehru, R.M. [Tata Memorial Hospital, Parel, Mumbai (India). Dept. of Medical Physics

    2001-10-01

    Purpose: To assess local control, survival and complications in patients with cervical carcinoma Stage IIB treated radically with transperineal Iridium-192 low-dose rate interstitial brachytherapy following external beam radiotherapy. Patients and Methods: 65 women (age 25-70 years, mean 47 years) with cervical carcinoma Stage IIB were initially treated with external beam radiotherapy on a telecobalt or 6 MW linear accelerator to a dose of 50 Gy delivered in 5-6 weeks. After 2-3 weeks of completing external radiation, patients received interstitial brachytherapy with Iridium-192 (activity 0.5-1 mCi/cm) using a Syed-Neblett perineal template. The median dose delivered to the implant volume was 24 Gy (range 20-32 Gy) delivered at an average dose rate of 0.70 Gy/h (range 0.40-1.20 Gy/h). A point defined at 1.5 cm lateral to the central uterine tandem at the level of os was taken as a representative for assessing the dose to the cervix. Mean doses delivered by interstitial brachytherapy to point A, cervix, point B and rectum were 38 Gy, 34 Gy, 16 Gy and 16 Gy, respectively. Results: At a median follow-up of 53 months, the actuarial disease free survival and overall survival for 65 patients at both 5 and 10 years was 64% and 44%, respectively. Response to radiotherapy was a strong predictor of local control with 82% of patients continuing to have pelvic control after initial complete response. Overall, nine (14%) patients had persistent disease, ten (15%) developed a central recurrence after initial control and three patients developed distant metastasis on follow-up. No patient had any immediate treatment-related complication. Late toxicity included grade I-II rectal reactions in five patients and grade IV bladder complication (vesico-vaginal fistula) in two patients. 5 years after treatment, one patient developed intestinal obstruction, which was relieved after conservative management. Two patients developed vaginal stenosis. The 5- and 10-year disease free survival

  18. Measuring the absorbed dose in critical organs during low rate dose brachytherapy with 137 Cs using thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Intracavitary Brachytherapy is one of the most used methods for the treatment of the cervical-uterine cancer. This treatment consists in the insertion of low rate dose 137Cs sources into the patient. The most used system for the treatment dose planning is that of Manchester. This planning is based on sources, which are considered fixed during the treatment. However, the experience has shown that, during the treatment, the sources could be displaced from its initial position, changing the dose from that previously prescribed. For this reason, it is necessary to make measurements of the absorbed dose to the surrounding organs (mainly bladder and rectum). This paper presents the results of measuring the absorbed dose using home-made LiF: Mg, Cu, P + Ptfe thermoluminescent dosimeters (TLD). Measurements were carried out in-vivo during 20 minutes at the beginning and at the end of the treatments. Results showed that the absorbed dose to the critical organs vary significantly due to the movement of the patient during the treatment. (Author)

  19. Dose calculation system for remotely supporting radiotherapy

    International Nuclear Information System (INIS)

    The dose calculation system IMAGINE is being developed keeping in mind remotely supporting external radiation therapy using photon beams. The system is expected to provide an accurate picture of the dose distribution in a patient body, using a Monte Carlo calculation that employs precise models of the patient body and irradiation head. The dose calculation will be performed utilising super-parallel computing at the dose calculation centre, which is equipped with the ITBL computer, and the calculated results will be transferred through a network. The system is intended to support the quality assurance of current, widely carried out radiotherapy and, further, to promote the prevalence of advanced radiotherapy. Prototypes of the modules constituting the system have already been constructed and used to obtain basic data that are necessary in order to decide on the concrete design of the system. The final system will be completed in 2007. (authors)

  20. Literature analysis of high dose rate brachytherapy fractionation schedules in the treatment of cervical cancer: is there an optimal fractionation schedule?

    International Nuclear Information System (INIS)

    Purpose: A literature review and analysis was performed to determine whether or not efficacious high dose rate (HDR) brachytherapy fractionation schedules exist for the treatment of cervical cancer. Methods and Materials: English language publications from peer reviewed journals were assessed to calculate the total contribution of dose to Point A from both the external and intracavitary portions of radiation for each stage of cervical cancer. Using the linear quadratic formula, the biologically effective dose to the tumor, using an α/β = 10, was calculated to Point A (Gy10) in order to determine a dose response relationship for local control and survival. Significant complications were assessed by calculating the dose to the late-responding tissues at Point A using an α/β = 3 (Gy3) as a surrogate for normal tissue tolerance, since few publications list the actual bladder and rectal doses. Results: For all stages combined, the median external beam fractionation schedule to Point A was 40 Gy in 20 fractions, while the median HDR fractionation schedule was 28 Gy in 4 fractions. For stages IB, IIB, and IIIB the median biologically effective dose to Point A (Gy10) was 96, 96 and 100 Gy10s, respectively. No correlation was identified between Point A BED (Gy10s) to either survival or pelvic control. A dose response relationship could also not be identified when correlating Point A Gy3s to complications. Conclusion: A dose response relationship could not be identified for either tumor control nor late tissue complications. These findings do not necessarily question the validity of the linear quadratic model, as much as they question the quality of the current HDR brachytherapy literature as it is currently presented and reported. Most of the HDR publications report inadequate details of the dose fractionation schedules. Only a minority of publications report significant complications using the actuarial method. In the future, all HDR publications for the treatment of

  1. High-dose-rate interstitial brachytherapy in early stage oral tongue cancer – 15 year experience from a tertiary care institute

    Science.gov (United States)

    Bansal, Anshuma; Ghoshal, Sushmita; Oinam, Arun S; Sharma, Suresh Chander; Dhanireddy, Bhaswanth

    2016-01-01

    Purpose To determine outcomes of interstitial high-dose-rate brachytherapy (HDR-BT) in patients with early stage oral tongue cancer. Material and methods Ninety-two patients with stage I and II oral tongue cancer were treated with HDR-BT between 1999 and 2014: brachytherapy alone = 62 (67.4%), and combination of external beam radiotherapy (EBRT) and brachytherapy = 30 (32.6%). Median follow-up was 53.5 months. Patterns of failure, overall survival (OS), disease-free survival (DFS), local control rates (LCR), and nodal control rates (NCR) were determined. Results 5-year OS, DFS, LCR, and NCR were 73.2%, 58.2%, 64.2%, and 83.8%, respectively. In total, 43 patients (46.7%) failed treatment: isolated local failures = 28 (30.4%), isolated nodal failures = 8 (8.7%), both local and regional failures = 7 (7.6%). While in T1 stage, 5 year LCR were significantly higher in brachytherapy alone group compared to combined EBRT and brachytherapy group (81.7% vs. 62.5%, p = 0.04), the isolated nodal failure rates were not significantly different among the two groups. For T2 stage, NCR were higher in combined EBRT and brachytherapy group compared to brachytherapy alone (92.9% vs. 74.3%). Acute mucositis (grade ≥ 2) was seen more in brachytherapy alone group compared to the combined modality group (87% vs. 66%), and this correlated significantly with the higher biological equivalent dose (BED) in the brachytherapy alone group. Conclusions Our study recommends treating patients with brachytherapy alone in T1 stage, and demonstrates the need for addressing nodal region either by neck dissection or nodal irradiation in T2 stage patients. Also, the study highlights the need for dose escalation (from the doses used in the study) in both T1 and T2 stage tumors when using interstitial brachytherapy either as sole modality or as a boost. PMID:26985198

  2. Equivalent-spherical-shield neutron dose calculations

    International Nuclear Information System (INIS)

    Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab

  3. Migration of a strand of four seeds in low-dose-rate brachytherapy

    Science.gov (United States)

    Dedic-Hagan, Jasmina; Teh, Amy Y M; Liang, Eisen; Collett, Nicholas; Woo, Henry H

    2014-01-01

    We report a case of stranded-seed migration (one strand of four seeds), via the prostatic venous plexus to the internal pudendal vein, in low-dose-rate (LDR) prostate brachytherapy. A 70-year-old man with low-risk prostate adenocarcinoma underwent transperineal permanent seed implantation. A total of 93 iodine-125 seeds were implanted (91 stranded seeds and 2 loose seeds). Immediate postimplantation fluoroscopic image and day 1 postimplantation CT scan indicated all implanted seeds to be within the vicinity of the prostate as planned. Day 30 pelvic X-ray and CT scan revealed migration of a strand of four seeds to the right pelvis (adjacent to ischial spine). At 2 years postimplantation, the patient continues to have good disease control with prostate specific antigen level of 0.69 μg/L, and asymptomatic. To the best of our knowledge, this is the first report of migration of an entire strand of seeds following LDR prostate brachytherapy. PMID:24879735

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  6. Clinical impact of MRI assisted dose volume adaptation and dose escalation in brachytherapy of locally advanced cervix cancer

    International Nuclear Information System (INIS)

    Background: To investigate the clinical impact of MRI based cervix cancer brachytherapy combined with external beam radiochemotherapy applying dose volume adaptation and dose escalation in a consecutive group of patients with locally advanced cervix cancer. Methods: In the period 1998-2003, 145 patients with cervix cancer stages IB-IVA were treated with definitive radiotherapy +/- cisplatin chemotherapy. Median age was 60 years. In 67 patients, the tumour size was 2-5 cm, in 78 patients it was >5 cm. In 29 cases the standard intracavitary technique was combined with interstitial brachytherapy. Total prescribed dose was 80-85 Gy (total biologically equivalent dose in 2 Gy fractions). Since 2001, MRI based treatment planning integrated systematic concepts for High Risk Clinical Target Volume (HR CTV) and organs at risk (OAR), biological modelling, Dose-Volume-Histogram analysis, dose-volume-adaptation (D90, D 2 cm3), and dose escalation, if appropriate and feasible. Findings: Dose volume adaptation was performed in 130/145 patients. The mean D90 during the whole period was 86 Gy, with a mean D90 of 81 Gy and 90 Gy during the first and second period, respectively (p 5 cm it was 71% in 1998-2000 and 90% in 2001-2003 (p = 0.05). Progression free survival (PFS) for true pelvis (local control) was 85%, PFS for distant metastases was 80%, both at 3 years. Local control for tumours >5 cm was 64% in 1998-2000 and 82% in 2001-2003 (p = 0.09) and 100% and 96%, respectively, for tumours 2-5 cm. PFS for distant metastases remained the same during the two treatment periods with 79% and 80%. Overall survival (OS) was 58%, and cancer-specific survival (CSS) was 68% at 3 years. In the two different periods improvement in OS was from 53% to 64% (p = 0.03) and in CSS from 62% to 74% (p = 0.13). Improvement occurred only in tumours >5 cm: OS 28% versus 58% (p = 0.003); CSS 40% versus 62% (p = 0.07). Actuarial late morbidity rate (LENT SOMA, grades 3 and 4) at 3 years was

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

    International Nuclear Information System (INIS)

    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)

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

    CERN Document Server

    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...

  9. Quality control of planning system of treatment for esophageal tumors with high dose rate brachytherapy; Controle de qualidade do sistema de planejamento de tratamento das neoplasias do esofago com braquiterapia de alta taxa de dose

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Penha M.; Ferreira, Fernando J.; Guedes, Laura M.A.; Manso, Luiz A.P. [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil). Setor de Fisica Medica; Castro, Betina W. [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil). Servico de Radioterapia; Ferreira, Maria A. [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil). Servico de Endoscopia

    2001-07-01

    An equation to control the quality of treatment for oesophageal tumors with high dose rate brachytherapy was adopted by the section of physics of the Instituto Nacional de Cancer. It was tested in 394 insertions in 20 (5.1%) a difference greater than 3% was observed between the duration of treatment calculated by the software of the equipment and the duration calculated by the equation. The largest difference observed was 9% in one insertion. By correcting the position of the patient on the X-ray table it has been possible to diminish this difference. (author)

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    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

  12. The long term effects of high dose rate brachytherapy on neointimal hyperplasia formation in the rat carotid artery - an update

    International Nuclear Information System (INIS)

    Purpose/Objective: A large number of investigators have begun utilizing radiation modalities in order to prevent or delay neointimal hyperplasia (NIH) formation. Following our initial successful studies looking at single fraction low doses of HDR brachytherapy given immediately after injury, we extended this model to look at the long term effects on the inhibition of NIH in the rat common carotid artery. Materials and Methods: The right common carotid arteries (CCA) of 4-5 month old male Sprague Dawley rats were injured using a 2F balloon catheter. Immediately post-injury, a delivery catheter was sutured alongside the injured artery and the vessel received either 0, 5, or 10 Gy irradiation using an Iridium 192 afterloader. Six months post-treatment, the animals were sacrificed and both the right and left CCA were harvested following perfusion fixation, and processed for light and electron micrography. Specimens were stained with PAS and the intima and media areas were calculated using a computer-assisted digitizing program. Additional immunocytochemical staining was carried out, looking particularly at PDGF. Results: In contrast to our previous findings which were assessed at 3 weeks post-treatment, at the later time point of 6 months post-treatment, there was no significant reduction in intimal area of the radiation-treated balloon-injured animals compared to the balloon-injured alone and the intima: media ratios was the same in both groups (Fig. 1). The lumenal area in both treatment groups was significantly reduced from normal controls (Fig. 2). Immunocytochemical staining for PDGF at 3 weeks demonstrated that there was an immediate (24 hours) release of growth factor from the medial smooth muscle in the balloon-injured animals; there was no similar release in the radiation-treated animals at the 1 day, 1 or 3 week time points. This will now be assessed at the later time points. Higher doses of 15-25 Gy are now being studied since other investigators have shown

  13. Prospective Clinical Trial of Bladder Filling and Three-Dimensional Dosimetry in High-Dose-Rate Vaginal Cuff Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To investigate the effect of bladder filling on dosimetry and to determine the best bladder dosimetric parameter for vaginal cuff brachytherapy. Methods and Materials: In this prospective clinical trial, a total of 20 women underwent vaginal cylinder high-dose-rate brachytherapy. The bladder was full for Fraction 2 and empty for Fraction 3. Dose-volume histogram and dose-surface histogram values were generated for the bladder, rectum, and urethra. The midline maximal bladder point (MBP) and the midline maximal rectal point were recorded. Paired t tests, Pearson correlations, and regression analyses were performed. Results: The volume and surface area of the irradiated bladder were significantly smaller when the bladder was empty than when full. Of the several dose-volume histogram and dose-surface histogram parameters evaluated, the bladder maximal dose received by 2 cm3 of tissue, volume of bladder receiving ≥50% of the dose, volume of bladder receiving ≥70% of the dose, and surface area of bladder receiving ≥50% of the dose significantly predicted for the difference between the empty vs. full filling state. The volume of bladder receiving ≥70% of the dose and the maximal dose received by 2 cm3 of tissue correlated significantly with the MBP. Bladder filling did not alter the volume or surface area of the rectum irradiated. However, an empty bladder did result in the nearest point of bowel being significantly closer to the vaginal cylinder than when the bladder was full. Conclusions: Patients undergoing vaginal cuff brachytherapy treated with an empty bladder have a lower bladder dose than those treated with a full bladder. The MBP correlated well with the volumetric assessments of bladder dose and provided a noninvasive method for reporting the MBP dose using three-dimensional imaging. The MBP can therefore be used as a surrogate for complex dosimetry in the clinic

  14. Evaluation of a real-time BeO ceramic fiber-coupled luminescence dosimetry system for dose verification of high dose rate brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Alexandre M. Caraça, E-mail: alexandre.santos@adelaide.edu.au [Department of Medical Physics, Royal Adelaide Hospital, Adelaide 5000, Australia and Institute for Photonics and Advanced Sensing, School of Physical Sciences, University of Adelaide, Adelaide 5005 (Australia); Mohammadi, Mohammad [Department of Medical Physics, Royal Adelaide Hospital, Adelaide 5000, Australia and Department of Medical Physics, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan 65167-3-8736 (Iran, Islamic Republic of); Shahraam, Afshar V. [Laser Physics and Photonic Devices Laboratories, School of Engineering, The University of South Australia, Adelaide 5095 (Australia); Institute for Photonics and Advanced Sensing, School of Physical Sciences, University of Adelaide, Adelaide 5005 (Australia)

    2015-11-15

    Purpose: The authors evaluate the capability of a beryllium oxide (BeO) ceramic fiber-coupled luminescence dosimeter, named radioluminescence/optically stimulated luminescence (RL/OSL) BeO FOD, for dosimetric verification of high dose rate (HDR) treatments. The RL/OSL BeO FOD is capable of RL and OSL measurements. Methods: The RL/OSL BeO FOD is able to be inserted in 6F proguide needles, used in interstitial HDR treatments. Using a custom built Perspex phantom, 6F proguide needles could be submerged in a water tank at 1 cm separations from each other. A second background fiber was required to correct for the stem effect. The stem effect, dose linearity, reproducibility, depth-dose curves, and angular and temperature dependency of the RL/OSL BeO FOD were characterised using an Ir-192 source. The RL/OSL BeO FOD was also applied to the commissioning of a 10 mm horizontal Leipzig applicator. Results: Both the RL and OSL were found to be reproducible and their percentage depth-dose curves to be in good agreement with those predicted via TG-43. A combined uncertainty of 7.9% and 10.1% (k = 1) was estimated for the RL and OSL, respectively. For the 10 mm horizontal Leipzig applicator, measured percentage depth doses were within 5% agreement of the published reference calculations. The output at the 3 mm prescription depth for a 1 Gy delivery was verified to be 0.99 ± 0.08 Gy and 1.01 ± 0.10 Gy by the RL and OSL, respectively. Conclusions: The use of the second background fiber under the current setup means that the two fibers cannot fit into a single 6F needle. Hence, use of the RL is currently not adequate for the purpose of in vivo brachytherapy dosimetry. While not real-time, the OSL is shown to be adequate for in vivo brachytherapy dosimetry.

  15. Radiological Dose Calculations for Fusion Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Michael L. Abbott; Lee C. Cadwallader; David A. Petti

    2003-04-01

    This report summarizes the results and rationale for radiological dose calculations for the maximally exposed individual during fusion accident conditions. Early doses per unit activity (Sieverts per TeraBecquerel) are given for 535 magnetic fusion isotopes of interest for several release scenarios. These data can be used for accident assessment calculations to determine if the accident consequences exceed Nuclear Regulatory Commission and Department of Energy evaluation guides. A generalized yearly dose estimate for routine releases, based on 1 Terabecquerel unit releases per radionuclide, has also been performed using averaged site parameters and assumed populations. These routine release data are useful for assessing designs against US Environmental Protection Agency yearly release limits.

  16. High dose rate brachytherapy for the treatment of soft tissue sarcoma of the extremity

    International Nuclear Information System (INIS)

    Purpose: we examined the role of preoperative neoadjuvant chemoradiation and adjuvant high-dose rate brachytherapy on the management of prognostically unfavorable soft tissue sarcomas of the extremities. Our goal was to examine the effect of high dose rate interstitial brachytherapy (HDR IBT) on reducing the risk of local recurrence following limb-sparing resection, as well as shortening treatment duration. Materials and methods: eleven patients, ranging in age from 31 to 73 years old, with soft tissue sarcoma of the extremity were treated at USC/Norris Comprehensive Cancer Center during 1994 and 1995. All patients had biopsy proven soft tissue sarcoma, and all were suitable candidates for limb-sparing surgery. All lesions were greater than 5cm in size and were primarily high grade. Tumor histologies included malignant fibrous histiocytoma (45%), liposarcoma (18%) and leiomyosarcoma, synovial cell sarcoma and spindle cell sarcoma (36%). Sites of tumor origin were the lower extremity (55%), upper extremity (18%) and buttock (9%), 1 patient (9%) had lesions in both the upper and lower extremity. Patients received HDR IBT following combined chemotherapy and external beam irradiation (EBRT) and en bloc resection of the sarcoma. Neoadjuvant chemotherapy consisted of three to four cycles of either Ifosfamide/Mesna with or without Adriamycin, or Mesna, Adriamycin, Ifosfamide and Dacarbazine. One patient received Cis-platin in addition to Ifos/Adr. A minimum of two cycles of chemotherapy were administered prior to EBRT. Additional cycles of chemotherapy were completed concurrently with EBRT but prior to HDR IBT. Preoperative EBRT doses ranging from 40 to 59.4 Gy were given in daily fractions of 180 to 200cGy. Following en bloc resection, HDR IBT was administered using the Omnitrontm 2000 remote afterloading system. Doses ranging from 13 to 30 Gy were delivered to the surgical tumor bed at depths of 0.5mm to 0.75mm from the radioactive source. Results: median follow-up was

  17. Braquiterapia endobrônquica de alta taxa de dose: estudo dosimétrico High dose-rate endobronchial brachytherapy: a dosimetric study

    Directory of Open Access Journals (Sweden)

    Regina Maria Godoy Lopes

    2010-02-01

    Full Text Available OBJETIVO: Avaliar a distribuição de dose em diferentes situações de braquiterapia endobrônquica de alta taxa de dose, com foco principalmente nos volumes de altas doses, e tentar definir situações de melhor ou pior distribuição de dose que possam servir de guia na prática clínica. MATERIAIS E MÉTODOS: Estudo teórico, simulando braquiterapia endobrônquica de alta taxa de dose utilizando dois cateteres, com variação da extensão de carregamento, angulação entre os cateteres, profundidade de cálculo e o intervalo entre as paradas da fonte. Com prescrição de 7,5 Gy, foram calculados os volumes englobados pelas isodoses correspondentes a 100%, 150% e 200% da dose prescrita (V100, V150 e V200, respectivamente e as razões V150/V100 e V200/V100. RESULTADOS: Os volumes aumentaram com o aumento da extensão de carregamento dos cateteres, profundidade de cálculo e angulação, com tendência a um aumento proporcionalmente menor para angulações maiores. As relações V150/V100 e V200/V100 foram, em geral, homogêneas, ao redor de 0,50 e 0,30, respectivamente. CONCLUSÃO: A distribuição de dose na situação considerada padrão é em geral adequada. Nenhum parâmetro específico que pudesse ser relacionado à maior toxicidade foi identificado. Recomendamos uma avaliação rápida da qualidade do implante por meio da análise das relações V150/V100 e V200/V100.OBJECTIVE: To evaluate the dose distribution in different situations of high dose-rate endobronchial brachytherapy, focusing especially on high-dose volumes, and try to identify better or worse situations in terms of dose distribution to aid as guidance in the clinical practice. MATERIALS AND METHODS: Theoretical study simulating high dose-rate endobronchial brachytherapy utilizing two catheters, varying the loading extent, angle between the catheters, prescription depth, and source step. With a prescription dose of 7.5 Gy, the volumes involved by the 100%, 150% and 200

  18. A hybrid evolutionary algorithm for multi-objective anatomy-based dose optimization in high-dose-rate brachytherapy

    International Nuclear Information System (INIS)

    Multiple objectives must be considered in anatomy-based dose optimization for high-dose-rate brachytherapy and a large number of parameters must be optimized to satisfy often competing objectives. For objectives expressed solely in terms of dose variances, deterministic gradient-based algorithms can be applied and a weighted sum approach is able to produce a representative set of non-dominated solutions. As the number of objectives increases, or non-convex objectives are used, local minima can be present and deterministic or stochastic algorithms such as simulated annealing either cannot be used or are not efficient. In this case we employ a modified hybrid version of the multi-objective optimization algorithm NSGA-II. This, in combination with the deterministic optimization algorithm, produces a representative sample of the Pareto set. This algorithm can be used with any kind of objectives, including non-convex, and does not require artificial importance factors. A representation of the trade-off surface can be obtained with more than 1000 non-dominated solutions in 2-5 min. An analysis of the solutions provides information on the possibilities available using these objectives. Simple decision making tools allow the selection of a solution that provides a best fit for the clinical goals. We show an example with a prostate implant and compare results obtained by variance and dose-volume histogram (DVH) based objectives

  19. 3D-printed surface mould applicator for high-dose-rate brachytherapy

    Science.gov (United States)

    Schumacher, Mark; Lasso, Andras; Cumming, Ian; Rankin, Adam; Falkson, Conrad B.; Schreiner, L. John; Joshi, Chandra; Fichtinger, Gabor

    2015-03-01

    In contemporary high-dose-rate brachytherapy treatment of superficial tumors, catheters are placed in a wax mould. The creation of current wax models is a difficult and time consuming proces.The irradiation plan can only be computed post-construction and requires a second CT scan. In case no satisfactory dose plan can be created, the mould is discarded and the process is repeated. The objective of this work was to develop an automated method to replace suboptimal wax moulding. We developed a method to design and manufacture moulds that guarantee to yield satisfactory dosimetry. A 3D-printed mould with channels for the catheters designed from the patient's CT and mounted on a patient-specific thermoplastic mesh mask. The mould planner was implemented as an open-source module in the 3D Slicer platform. Series of test moulds were created to accommodate standard brachytherapy catheters of 1.70mm diameter. A calibration object was used to conclude that tunnels with a diameter of 2.25mm, minimum 12mm radius of curvature, and 1.0mm open channel gave the best fit for this printer/catheter combination. Moulds were created from the CT scan of thermoplastic mesh masks of actual patients. The patient-specific moulds have been visually verified to fit on the thermoplastic meshes. The masks were visually shown to fit onto the thermoplastic meshes, next the resulting dosimetry will have to be compared with treatment plans and dosimetry achieved with conventional wax moulds in order to validate our 3D printed moulds.

  20. Unified registration framework for cumulative dose assessment in cervical cancer across external beam radiotherapy and brachytherapy

    Science.gov (United States)

    Roy, Sharmili; Totman, John J.; Choo, Bok A.

    2016-03-01

    Dose accumulation across External Beam Radiotherapy (EBRT) and Brachytherapy (BT) treatment fractions in cervical cancer is extremely challenging due to structural dissimilarities and large inter-fractional anatomic deformations between the EBRT and BT images. The brachytherapy applicator and the bladder balloon, present only in the BT images, introduce missing structural correspondences for the underlying registration problem. Complex anatomical deformations caused by the applicator and the balloon, different rectum and bladder filling and tumor shrinkage compound the registration difficulties. Conventional free-form registration methods struggle to handle such topological differences. In this paper, we propose a registration pipeline that first transforms the original images to their distance maps based on segmentations of critical organs and then performs non-linear registration of the distance maps. The resulting dense deformation field is then used to transform the original anatomical image. The registration accuracy is evaluated on 27 image pairs from stage 2B-4A cervical cancer patients. The algorithm reaches a Hausdorff distance of close to 0:5 mm for the uterus, 2:2 mm for the bladder and 1:7 mm for the rectum when applied to (EBRT,BT) pairs, taken at time points more than three months apart. This generalized model-free framework can be used to register any combination of EBRT and BT images as opposed to methods in the literature that are tuned for either only (BT,BT) pair, or only (EBRT,EBRT) pair or only (BT,EBRT) pair. A unified framework for 3D dose accumulation across multiple EBRT and BT fractions is proposed to facilitate adaptive personalized radiation therapy.

  1. High-Dose-Rate Brachytherapy Boost for Prostate Cancer: Comparison of Two Different Fractionation Schemes

    International Nuclear Information System (INIS)

    Purpose: This is a retrospective study comparing our experience with high-dose-rate (HDR) brachytherapy boost for prostate cancer, using two different fractionation schemes, 600 cGy × 3 fractions (patient group 1) and 950 cGy × 2 fractions (patient group 2). Methods and Materials: A total of 165 patients were treated for prostate cancer using external beam radiation therapy up to a dose of 45 Gy, followed by an HDR brachytherapy prostate radiation boost. Between July 1997 and Nov 1999, 64 patients were treated with an HDR boost of 600 cGy × 3 fractions; and between June 2000 and Nov 2005, 101 patients were treated with an HDR boost of 950 cGy × 2 fractions. All but 9 patients had at least one of the following risk features: pretreatment prostate-specific antigen (PSA) level >10, a Gleason score ≥7, and/or clinical stage T3 disease. Results: Median follow-up was 105 months for group 1 and 43 months for group 2. Patients in group 2 had a greater number of high-risk features than group 1 (p = 0.02). Adjusted for comparable follow-up, there was no difference in biochemical no-evidence-of-disease (bNED) rate between the two fractionation scheme approaches, with 5-year Kaplan-Meier estimates of 93.5% in group 1 and 87.3% in group 2 (p = 0.19). The 5-year estimates of progression-free survival were 86% for group 1 and 83% for group 2 (p = 0.53). Among high-risk patients, there were no differences in bNED or PFS rate due to fractionation. Conclusions: Results were excellent for both groups. Adjusted for comparable follow-up, no differences were found between groups.

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

    International Nuclear Information System (INIS)

    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.

  3. Use of Monte Carlo Methods in brachytherapy; Uso del metodo de Monte Carlo en braquiterapia

    Energy Technology Data Exchange (ETDEWEB)

    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)

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

  7. The Adjoint Method for The Optimization of Brachytherapy and Radiotherapy Patient Treatment Planning Procedures Using Monte Carlo Calculations

    International Nuclear Information System (INIS)

    The goal of this project is to investigate the use of the adjoint method, commonly used in the reactor physics community, for the optimization of radiation therapy patient treatment plans. Two different types of radiation therapy are being examined, interstitial brachytherapy and radiotherapy. In brachytherapy radioactive sources are surgically implanted within the diseased organ such as the prostate to treat the cancerous tissue. With radiotherapy, the x-ray source is usually located at a distance of about 1-meter from the patient and focused on the treatment area. For brachytherapy the optimization phase of the treatment plan consists of determining the optimal placement of the radioactive sources, which delivers the prescribed dose to the disease tissue while simultaneously sparing (reducing) the dose to sensitive tissue and organs. For external beam radiation therapy the optimization phase of the treatment plan consists of determining the optimal direction and intensity of beam, which provides complete coverage of the tumor region with the prescribed dose while simultaneously avoiding sensitive tissue areas. For both therapy methods, the optimal treatment plan is one in which the diseased tissue has been treated with the prescribed dose and dose to the sensitive tissue and organs has been kept to a minimum

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

    CERN Document Server

    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.

  9. Real-time inverse high-dose-rate brachytherapy planning with catheter optimization by compressed sensing-inspired optimization strategies

    Science.gov (United States)

    Guthier, C. V.; Aschenbrenner, K. P.; Müller, R.; Polster, L.; Cormack, R. A.; Hesser, J. W.

    2016-08-01

    This paper demonstrates that optimization strategies derived from the field of compressed sensing (CS) improve computational performance in inverse treatment planning (ITP) for high-dose-rate (HDR) brachytherapy. Following an approach applied to low-dose-rate brachytherapy, we developed a reformulation of the ITP problem with the same mathematical structure as standard CS problems. Two greedy methods, derived from hard thresholding and subspace pursuit are presented and their performance is compared to state-of-the-art ITP solvers. Applied to clinical prostate brachytherapy plans speed-up by a factor of 56–350 compared to state-of-the-art methods. Based on a Wilcoxon signed rank-test the novel method statistically significantly decreases the final objective function value (p  optimization times were below one second and thus planing can be considered as real-time capable. The novel CS inspired strategy enables real-time ITP for HDR brachytherapy including catheter optimization. The generated plans are either clinically equivalent or show a better performance with respect to dosimetric measures.

  10. Study of dose deposition of 125I brachytherapy seeds in a solid water phantom

    International Nuclear Information System (INIS)

    Currently, many kinds of radioactive sources are used in brachytherapy for cancer treatment. The 125I seed used in this work is the model Onco Seed 6711, produced by Oncura, which is ranked among the best options for treating prostate cancer. This source emits gamma photons with average energy of 28 keV and has a half-life of 59.4 days. After the implants, the natural movement of the organ can cause the seeds undergo slight displacements relative to the position originally planned, which can cause changes in dose distribution in the tumor volume. This work seeks to compare the dose distribution in a solid water phantom of two symmetrical, but different arrangements of four seeds. For this study, the phantom was machined to accommodate the seeds and TLD-100 LiF rod type dosimeters. The study, using TLD dosimeters, was conducted up to 4 cm of the settings. In addition, an Ebt Gafchromic radiochromic film was positioned over the two configurations during a period of time enough for 1 Gy deposition on it, to observe possible changes in the shape of the isodose curves. The TLD results showed a difference up to 35.8% of the dose deposited in the center of the configurations and different doses were deposited at distances corresponding to 1 and 2 cm radius from the symmetrical seeds arrangements. After 3 cm radius, the dose discrepancy is no longer significant. Another important point is that despite the configurations are symmetric, different dose values were deposited at symmetrical points. The isodose qualitative curves shown by the films showed a difference in the shape of that curves. Thus, the different positions of the seeds proved decisive in dose deposition and this fact should be taken into consideration in planning treatment

  11. Historical river flow rates for dose calculations

    International Nuclear Information System (INIS)

    Annual average river flow rates are required input to the LADTAP Computer Code for calculating offsite doses from liquid releases of radioactive materials to the Savannah River. The source of information on annual river flow rates used in dose calculations varies, depending on whether calculations are for retrospective releases or prospective releases. Examples of these types of releases are: Retrospective - releases from routine operations (annual environmental reports) and short term release incidents that have occurred. Prospective - releases that might be expected in the future from routine or abnormal operation of existing or new facilities (EIS's, EID'S, SAR'S, etc.). This memorandum provides historical flow rates at the downstream gauging station at Highway 301 for use in retrospective dose calculations and derives flow rate data for the Beaufort-Jasper and Port Wentworth water treatment plants

  12. Monte Carlo calculation of spectral lines for use in the Italian Protocol for dosimetry in Brachytherapy

    International Nuclear Information System (INIS)

    The Italian Committee for Dosimetry in Radiotherapy is about to produce a protocol for the dosimetry of brachytherapy sources that defines methods to measure the quantity 'air kerma rate in free air in a reference point' using ionisation chambers. Several parameters and quantities necessary to apply the protocol have to be calculated. In this presentation we show the methods used to calculate two of them: Pair, that account for the attenuation and scattering of photons in air; Nk(source), the calibration factor for each dosimeter and source type. Both quantities have been calculated by means of Monte Carlo simulations. To calculate Pair we score the photon fluence in the detector area, separately for 'primary photons', i.e. photons coming directly from the source without interacting in air; 'scattered photons', i.e. photons that are diffused from the air towards the scoring region; 'attenuated photons', i.e. primary photons directed towards the scoring region that are subtracted from the primary fluence by interactions in air. Pair is calculated as a combination of those fluences. Nk(source) is calculated starting from the air kerma rates due to spectral lines emitted by the source and from the corresponding calibration factors. The Monte Carlo code EGS4 is used, in a version modified in order to take into account the characteristics X-ray production. Results are shown for some of the sources most used in Italy

  13. High-Dose-Rate intraluminal brachytherapy for biliary obstruction by secondary malignant biliary tumors

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Won Sup; Kim, Tae Hyun; Yang, Dae Sik; Choi, Myung Sun; Kim, Chul Yong [College of Medicine, Korea Univ., Seoul (Korea, Republic of)

    2003-03-01

    To analyze the survival period, prognostic factors and complications of patients having under gone high-dose-rate intraluminal brachytherapy (HDR-ILB) as a salvage radiation therapy, while having a catheter, for percutaneous transhepatic biliary drainage (PTBD), inserted due to biliary obstruction caused by a secondary malignant biliary tumor. A retrospective study was performed on 24 patients having undergone HDR-ILB, with PTBD catheter insertion, between December 1992 and August 2001, Their median age was 58.5, ranging from 35 to 82 years. The primary cancer site were the stomach, gallbladder, liver, pancreas and the colon, with 12, 6, 3, 2 and 1 cases, respectively. Eighteen patients were treated with external beam radiation therapy and HDR-ILB, while six were treated with HDR-ILB only. The total external beam, and brachytherapy radiations dose were 30-61.2 and 9-30 Gy, with median doses of 50 and 15 Gy, respectively. Of the 24 patients analyzed, 22 died during the follow-up period, with a median survival of 7.3 months. The 6 and 12 months survival rates were 54.2 (13 patients) and 20.8% (5 patients), respectively. The median survivals for stomach and gallbladder cancers were 7.8 and 10.2 months, respectively. According to the univariate analysis, a significant factor affecting survival of over one year was the total radiation dose (over 50 Gy) (0=0.0200), with all the patients surviving more than one year had been irradiated with more than 50 Gy. The acute side effects during the radiation therapy were managed with conservative treatment. During the follow-up period, 5 patients showed symptoms of cholangitis due to the radiation therapy. An extension to the survival of those patients treated with HDR-ILB is suggested compared to the median historical survival of those patients treated with external biliary drainage. A boost radiation dose could be effectively given, by performing HDR-ILB, which is a prognostic factor. In addition, the acute complications of

  14. Comparison of High-Dose Proton Radiotherapy and Brachytherapy in Localized Prostate Cancer: A Case-Matched Analysis

    International Nuclear Information System (INIS)

    Purpose: To report a case-matched analysis comparing high-dose external-beam radiation (EBRT) for prostate cancer delivered on Proton Radiation Oncology Group (PROG) 95-09, a randomized trial, with permanent prostate brachytherapy over the same era. Methods: From 1996 to 1999, 196 patients were accrued to the high-dose arm (79.2 Gray equivalent (GyE) using photons and protons) of PROG 95-09 at the Massachusetts General Hospital and Loma Linda University Medical Center. Entry criteria specified T1–2 and prostate-specific antigen ≤15 ng/mL. When Gleason score >7 was excluded, 177 men were left for case matching. At Massachusetts General Hospital, 203 similar patients were treated by a single brachytherapist from 1997 to 2002. Minimum follow-up was 3 years. Case matching, based on T stage, Gleason score, prostate-specific antigen, and age resulted in 141 matches (282 patients). Median follow-up was 8.6 and 7.4 years for EBRT and brachytherapy, respectively. The primary endpoint was biochemical failure (BF). Results: Using the Phoenix definition, the 8-year BF rates were 7.7% and 16.1% for EBRT and brachytherapy, respectively (p = 0.42). A stratified analysis was performed by risk group. In the EBRT group, 113 and 28 patients were low and intermediate risk, respectively. In the brachytherapy group, 118 and 23 were. When stratified by risk group, the BF rates were similar by either technique. Conclusions: High-dose EBRT and brachytherapy result in similar BF rates for men with localized prostate cancer. Comparative quality-of-life and cost-effectiveness studies are warranted.

  15. Inverse Planned High-Dose-Rate Brachytherapy for Locoregionally Advanced Cervical Cancer: 4-Year Outcomes

    Energy Technology Data Exchange (ETDEWEB)

    Tinkle, Christopher L.; Weinberg, Vivian [Department of Radiation Oncology, University of California, San Francisco, California (United States); Chen, Lee-May [Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California (United States); Littell, Ramey [Gynecologic Oncology, The Permanente Medical Group, San Francisco, California (United States); Cunha, J. Adam M.; Sethi, Rajni A. [Department of Radiation Oncology, University of California, San Francisco, California (United States); Chan, John K. [Gynecologic Oncology, California Pacific Medical Center, San Francisco, California (United States); Hsu, I-Chow, E-mail: ichow.hsu@ucsf.edu [Department of Radiation Oncology, University of California, San Francisco, California (United States)

    2015-08-01

    Purpose: Evaluate the efficacy and toxicity of image guided brachytherapy using inverse planning simulated annealing (IPSA) high-dose-rate brachytherapy (HDRB) boost for locoregionally advanced cervical cancer. Methods and Materials: From December 2003 through September 2009, 111 patients with primary cervical cancer were treated definitively with IPSA-planned HDRB boost (28 Gy in 4 fractions) after external radiation at our institution. We performed a retrospective review of our experience using image guided brachytherapy. Of the patients, 70% had a tumor size >4 cm, 38% had regional nodal disease, and 15% had clinically evident distant metastasis, including nonregional nodal disease, at the time of diagnosis. Surgical staging involving pelvic lymph node dissection was performed in 15% of patients, and 93% received concurrent cisplatin-based chemotherapy. Toxicities are reported according to the Common Terminology Criteria for Adverse Events version 4.0 guidelines. Results: With a median follow-up time of 42 months (range, 3-84 months), no acute or late toxicities of grade 4 or higher were observed, and grade 3 toxicities (both acute and late) developed in 8 patients (1 constitutional, 1 hematologic, 2 genitourinary, 4 gastrointestinal). The 4-year Kaplan-Meier estimate of late grade 3 toxicity was 8%. Local recurrence developed in 5 patients (4 to 9 months after HDRB), regional recurrence in 3 (6, 16, and 72 months after HDRB), and locoregional recurrence in 1 (4 months after HDR boost). The 4-year estimates of local, locoregional, and distant control of disease were 94.0%, 91.9%, and 69.1%, respectively. The overall and disease-free survival rates at 4 years were 64.3% (95% confidence interval [CI] of 54%-73%) and 61.0% (95% CI, 51%-70%), respectively. Conclusions: Definitive radiation by use of inverse planned HDRB boost for locoregionally advanced cervical cancer is well tolerated and achieves excellent local control of disease. However, overall

  16. Validation of dose calculation programmes for recycling

    International Nuclear Information System (INIS)

    This report contains the results from an international project initiated by the SSI in 1999. The primary purpose of the project was to validate some of the computer codes that are used to estimate radiation doses due to the recycling of scrap metal. The secondary purpose of the validation project was to give a quantification of the level of conservatism in clearance levels based on these codes. Specifically, the computer codes RESRAD-RECYCLE and CERISE were used to calculate radiation doses to individuals during the processing of slightly contaminated material, mainly in Studsvik, Sweden. Calculated external doses were compared with measured data from different steps of the process. The comparison of calculations and measurements shows that the computer code calculations resulted in both overestimations and underestimations of the external doses for different recycling activities. The SSI draws the conclusion that the accuracy is within one order of magnitude when experienced modellers use their programmes to calculate external radiation doses for a recycling process involving material that is mainly contaminated with cobalt-60. No errors in the codes themselves were found. Instead, the inaccuracy seems to depend mainly on the choice of some modelling parameters related to the receptor (e.g., distance, time, etc.) and simplifications made to facilitate modelling with the codes (e.g., object geometry). Clearance levels are often based on studies on enveloping scenarios that are designed to cover all realistic exposure pathways. It is obvious that for most practical cases, this gives a margin to the individual dose constraint (in the order of 10 micro sievert per year within the EC). This may be accentuated by the use of conservative assumptions when modelling the enveloping scenarios. Since there can obviously be a fairly large inaccuracy in the calculations, it seems reasonable to consider some degree of conservatism when establishing clearance levels based on

  17. Assessment of dose-volume histograms in brachytherapy 3D high-rate; Evaluacion de los histogramas dosis volumen en braquiterapia de alta tasa 3D

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Barrado, A.; Tripero Oter, J.; Sanchez Jimenez, E.; Sanchez-Reyes, A.

    2013-07-01

    The use of systems of treatment planning using 3D reconstruction algorithms are becoming more frequent in brachytherapy treatments. The implementation of these systems entails great qualitative and quantitative procedural changes in the way to evaluate the clinical dosimetry about the 2D classical systems. This paper describes the experience of our Centre in employment and prescription dose using histograms dose-volume in the treatment of brachytherapy of high rate. (Author)

  18. Dose to the Bladder Neck Is the Most Important Predictor for Acute and Late Toxicity After Low-Dose-Rate Prostate Brachytherapy: Implications for Establishing New Dose Constraints for Treatment Planning

    International Nuclear Information System (INIS)

    Purpose: To identify an anatomic structure predictive for acute (AUT) and late (LUT) urinary toxicity in patients with prostate cancer treated with low-dose-rate brachytherapy (LDR) with or without external beam radiation therapy (EBRT). Methods and Materials: From July 2002 to January 2013, 927 patients with prostate cancer (median age, 66 years) underwent LDR brachytherapy with Iodine 125 (n=753) or Palladium 103 (n=174) as definitive treatment (n=478) and as a boost (n=449) followed by supplemental EBRT (median dose, 50.4 Gy). Structures contoured on the computed tomographic (CT) scan on day 0 after implantation included prostate, urethra, bladder, and the bladder neck, defined as 5 mm around the urethra between the catheter balloon and the prostatic urethra. AUT and LUT were assessed with the Common Terminology Criteria for Adverse Events, version4. Clinical and dosimetric factors associated with AUT and LUT were analyzed with Cox regression and receiver operating characteristic analysis to calculate area under the receiver operator curve (ROC) (AUC). Results: Grade ≥2 AUT and grade ≥2 LUT occurred in 520 patients (56%) and 154 patients (20%), respectively. No grade 4 toxicities were observed. Bladder neck D2cc retained a significant association with AUT (hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.03-1.04; P<.0001) and LUT (HR, 1.01; 95% CI, 1.00-1.03; P=.014) on multivariable analysis. In a comparison of bladder neck with the standard dosimetric variables by use of ROC analysis (prostate V100 >90%, D90 >100%, V150 >60%, urethra D20 >130%), bladder neck D2cc >50% was shown to have the strongest prognostic power for AUT (AUC, 0.697; P<.0001) and LUT (AUC, 0.620; P<.001). Conclusions: Bladder neck D2cc >50% was the strongest predictor for grade ≥2 AUT and LUT in patients treated with LDR brachytherapy. These data support inclusion of bladder neck constraints into brachytherapy planning to decrease urinary toxicity

  19. Using the Computed Tomography in Comparison to the Orthogonal Radiography Based Treatment Planning in High dose Rate (HDR) Brachytherapy in Cervical Uteri Cancer Patients; A Single Institution Feasibility Study

    International Nuclear Information System (INIS)

    Brachytherapy is an integral part in the treatment of cervical uteri cancer patients. Orthogonal treatment planning is the standard mode of calculation based on reference points. Introduction of the innovative 3-D computer based treatment planning allows accurate calculation based on volumetric information as regards the target volume and organs at risk (OAR). Also provide dose volume histogram (DVH) for proper estimation of the dose in relation to the volume. Aim: To correlate and compare the information obtained from the two approaches for high dose rate brachytherapy of cervical uteri cancer; the orthogonal conventional method and the computerized tomography (CT) three dimensions (3D) based calculation method in relation to the target and organ at risk (OAR). Methods: From 6 patients of cervical uteri cancer, 21 applications with orthogonal planning using the Brachy Vision treatment planning system version 7.3.10 were performed. In 10 applications; comparison between orthogonal and CT based planning was done. In orthogonal planning; the dose to point A, rectum and bladder were defined according to the American Brachytherapy Society (ABS) recommendation. From the CT based planning the target volume and dose volume histogram (DVH) were calculated for the clinical target volume (CTV), rectum and bladder. From these two sets, information was obtained and compared and mean values were derived. Results: For dose prescription at point A, an average of 63.5% of CTV received the prescribed dose. The mean ICRU dose to the bladder point is 2.9 Gy±l .2 SD (Standard Deviation) and 17% of the bladder volume derived from CT was encompassed by 2.9 Gy isodose line. The mean ICRU dose at the rectum point is 3.4 Gy±1.2 SD and 21% of the rectum volume from CT was encompassed by 3.4 Gy isodose line. The maximum dose to the rectum and the bladder derived from the CT and compared to the maximal dose at ICRU is 1.7 and 2.8 times higher than the orthogonal reference points; with the

  20. The application of Geant4 simulation code for brachytherapy treatment

    CERN Document Server

    Agostinelli, S; Garelli, S; Paoli, G; Nieminen, P; Pia, M G

    2000-01-01

    Brachytherapy is a radiotherapeutic modality that makes use of radionuclides to deliver a high radiation dose to a well-defined volume while sparing surrounding healthy structures. At the National Institute for Cancer Research of Genova a High Dose Rate remote afterloading system provides Ir(192) endocavitary brachytherapy treatments. We studied the possibility to use the Geant4 Monte Carlo simulation toolkit in brachytherapy for calculation of complex physical parameters, not directly available by experiment al measurements, used in treatment planning dose deposition models.

  1. American Society for Radiation Oncology (ASTRO) and American College of Radiology (ACR) Practice Guideline for the Performance of High-Dose-Rate Brachytherapy

    International Nuclear Information System (INIS)

    High-Dose-Rate (HDR) brachytherapy is a safe and efficacious treatment option for patients with a variety of different malignancies. Careful adherence to established standards has been shown to improve the likelihood of procedural success and reduce the incidence of treatment-related morbidity. A collaborative effort of the American College of Radiology (ACR) and American Society for Therapeutic Radiation Oncology (ASTRO) has produced a practice guideline for HDR brachytherapy. The guideline defines the qualifications and responsibilities of all the involved personnel, including the radiation oncologist, physicist and dosimetrists. Review of the leading indications for HDR brachytherapy in the management of gynecologic, thoracic, gastrointestinal, breast, urologic, head and neck, and soft tissue tumors is presented. Logistics with respect to the brachytherapy implant procedures and attention to radiation safety procedures and documentation are presented. Adherence to these practice guidelines can be part of ensuring quality and safety in a successful HDR brachytherapy program.

  2. High-Dose-Rate Monotherapy: Safe and Effective Brachytherapy for Patients With Localized Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: High-dose-rate (HDR) brachytherapy used as the only treatment (monotherapy) for early prostate cancer is consistent with current concepts in prostate radiobiology, and the dose is reliably delivered in a prospectively defined anatomic distribution that meets all the requirements for safe and effective therapy. We report the disease control and toxicity of HDR monotherapy from California Endocurietherapy (CET) and William Beaumont Hospital (WBH) in low- and intermediate-risk prostate cancer patients. Methods and Materials: There were 298 patients with localized prostate cancer treated with HDR monotherapy between 1996 and 2005. Two biologically equivalent hypofractionation protocols were used. At CET the dose was 42 Gy in six fractions (two implantations 1 week apart) delivered to a computed tomography–defined planning treatment volume. At WBH the dose was 38 Gy in four fractions (one implantation) based on intraoperative transrectal ultrasound real-time treatment planning. The bladder, urethral, and rectal dose constraints were similar. Toxicity was scored with the National Cancer Institute Common Toxicity Criteria for Adverse Events version 3. Results: The median follow-up time was 5.2 years. The median age of the patients was 63 years, and the median value of the pretreatment prostate-specific antigen was 6.0 ng/mL. The 8-year results were 99% local control, 97% biochemical control (nadir +2), 99% distant metastasis–free survival, 99% cause-specific survival, and 95% overall survival. Toxicity was scored per event, meaning that an individual patient with more than one symptom was represented repeatedly in the morbidity data table. Genitourinary toxicity consisted of 10% transient Grade 2 urinary frequency or urgency and 3% Grade 3 episode of urinary retention. Gastrointestinal toxicity was <1%. Conclusions: High disease control rates and low morbidity demonstrate that HDR monotherapy is safe and effective for patients with localized prostate cancer.

  3. Low-dose-rate brachytherapy for patients with transurethral resection before implantation in prostate cancer: long-term results

    Energy Technology Data Exchange (ETDEWEB)

    Prada, Pedro J.; Anchuelo, Javier; Blanco, Ana Garcia; Paya, Gema; Cardenal, Juan; Acuña, Enrique; Ferri, Maria [Department of Radiation Oncology, Hospital Universitario Marqués de Valdecilla, Santander, Cantabria (Spain); Vazquez, Andres; Pacheco, Maite; Sanchez, Jesica [Department of Radiation Physics, Hospital Universitario Marqués de Valdecilla, Santander, Cantabria (Spain)

    2016-01-15

    Objectives: We analyzed the long-term oncologic outcome for patients with prostate cancer and transurethral resection who were treated using low-dose-rate (LDR) prostate brachytherapy. Methods and Materials: From January 2001 to December 2005, 57 consecutive patients were treated with clinically localized prostate cancer. No patients received external beam radiation. All of them underwent LDR prostate brachytherapy. Biochemical failure was defined according to the 'Phoenix consensus'. Patients were stratified as low and intermediate risk based on The Memorial Sloan Kettering group definition. Results: The median follow-up time for these 57 patients was 104 months. The overall survival according to Kaplan-Meier estimates was 88% (±6%) at 5 years and 77% (±6%) at 12 years. The 5 and 10 years for failure in tumour-free survival (TFS) was 96% and respectively (±2%), whereas for biochemical control was 94% and respectively (±3%) at 5 and 10 years, 98% (±1%) of patients being free of local recurrence. A patient reported incontinence after treatment (1.7%). The chronic genitourinary complains grade I were 7% and grade II, 10%. At six months 94% of patients reported no change in bowel function. Conclusions: The excellent long-term results and low morbidity presented, as well as the many advantages of prostate brachytherapy over other treatments, demonstrates that brachytherapy is an effective treatment for patients with transurethral resection and clinical organ-confined prostate cancer. (author)

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    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.

  6. Multigroup neutron dose calculations for proton therapy

    International Nuclear Information System (INIS)

    We have developed tools for the preparation of coupled multigroup proton/neutron cross section libraries. Our method is to use NJOY to process evaluated nuclear data files for incident particles below 150 MeV and MCNPX to produce data for higher energies. We modified the XSEX3 program of the MCNPX code system to produce Legendre expansions of scattering matrices generated by sampling the physics models that are comparable to the output of the GROUPR routine of NJOY. Our code combines the low and high energy scattering data with user input stopping powers and energy deposition cross sections that we also calculated using MCNPX. Our code also calculates momentum transfer coefficients for the library and optionally applies an energy straggling model to the scattering cross sections and stopping powers. The motivation was initially for deterministic solution of space radiation shielding calculations using Attila, but noting that proton therapy treatment planning may neglect secondary neutron dose assessments because of difficulty and expense, we have also investigated the feasibility of multi group methods for this application. We have shown that multigroup MCNPX solutions for secondary neutron dose compare well with continuous energy solutions and are obtainable with less than half computational cost. This efficiency comparison neglects the cost of preparing the library data, but this becomes negligible when distributed over many multi group calculations. Our deterministic calculations illustrate recognized obstacles that may have to be overcome before discrete ordinates methods can be efficient alternatives for proton therapy neutron dose calculations

  7. Multigroup neutron dose calculations for proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kelsey Iv, Charles T [Los Alamos National Laboratory; Prinja, Anil K [Los Alamos National Laboratory

    2009-01-01

    We have developed tools for the preparation of coupled multigroup proton/neutron cross section libraries. Our method is to use NJOY to process evaluated nuclear data files for incident particles below 150 MeV and MCNPX to produce data for higher energies. We modified the XSEX3 program of the MCNPX code system to produce Legendre expansions of scattering matrices generated by sampling the physics models that are comparable to the output of the GROUPR routine of NJOY. Our code combines the low and high energy scattering data with user input stopping powers and energy deposition cross sections that we also calculated using MCNPX. Our code also calculates momentum transfer coefficients for the library and optionally applies an energy straggling model to the scattering cross sections and stopping powers. The motivation was initially for deterministic solution of space radiation shielding calculations using Attila, but noting that proton therapy treatment planning may neglect secondary neutron dose assessments because of difficulty and expense, we have also investigated the feasibility of multi group methods for this application. We have shown that multigroup MCNPX solutions for secondary neutron dose compare well with continuous energy solutions and are obtainable with less than half computational cost. This efficiency comparison neglects the cost of preparing the library data, but this becomes negligible when distributed over many multi group calculations. Our deterministic calculations illustrate recognized obstacles that may have to be overcome before discrete ordinates methods can be efficient alternatives for proton therapy neutron dose calculations.

  8. A modelled comparison of prostate cancer control rates after high-dose-rate brachytherapy (3145 multicentre patients) combined with, or in contrast to, external-beam radiotherapy

    International Nuclear Information System (INIS)

    Background and purpose: To analyse biochemical relapse-free-survival results for prostate cancer patients receiving combined external beam and high-dose-rate brachytherapy, in comparison with expected results using projections based on dose/fractionation/response parameter values deduced from a previous external-beam-alone 5969-patient multicentre dataset. Material and methods: Results on a total of 3145 prostate cancer patients receiving brachytherapy (BT) as part or all of their treatment were collected from 10 institutions, and subjected to linear-quadratic (LQ) modelling of dose response and fractionation parameters. Results: Treatments with BT components of less than 25 Gy, 3–4 BT fractions, doses per BT fraction up to 6 Gy, and treatment times of 3–7 weeks, all gave outcomes expected from LQ projections of the external-beam-alone data (α/β = 1.42 Gy). However, BT doses higher than 30 Gy, 1–2 fractions, 9 fractions (BT alone), doses per fraction of 9–15 Gy, and treatment in only 1 week (one example), gave local control levels lower than the expected levels by up to ∼35%. Conclusions: There are various potential causes of the lower-than-projected control levels for some schedules of brachytherapy: it seems plausible that cold spots in the brachytherapy dose distribution may be contributory, and the applicability of the LQ model at high doses per fraction remains somewhat uncertain. The results of further trials may help elucidate the true benefit of hypofractionated high-dose-rate brachytherapy

  9. There Is No Correlation Between Erectile Dysfunction and Dose to Penile Bulb and Neurovascular Bundles Following Real-Time Low-Dose-Rate Prostate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: We evaluated the relationship between the onset of erectile dysfunction and dose to the penile bulb and neurovascular bundles (NVBs) after real-time ultrasound-guided prostate brachytherapy. Methods and Materials: One hundred forty-seven patients who underwent prostate brachytherapy met the following eligibility criteria: (1) treatment with 125I brachytherapy to a prescribed dose of 160 Gy with or without hormones without supplemental external beam radiation therapy, (2) identification as potent before the time of implantation based on a score of 2 or higher on the physician-assigned Mount Sinai Erectile Function Score and a score of 16 or higher on the abbreviated International Index of Erectile Function patient assessment, and (3) minimum follow-up of 12 months. Median follow-up was 25.7 months (range, 12-47 months). Results: The 3-year actuarial rate of impotence was 23% (34 of 147 patients). An additional 43% of potent patients (49 of 113 patients) were using a potency aid at last follow-up. The penile bulb volume receiving 100% of the prescription dose (V100) ranged from 0-0.05 cc (median, 0 cc), with a dose to the hottest 5% (D5) range of 12.5-97.9 Gy (median, 40.8 Gy). There was no correlation between penile bulb D5 or V100 and postimplantation impotency on actuarial analysis. For the combined right and left NVB structures, V100 range was 0.3-5.1 cc (median, 1.8 cc), and V150 range was 0-1.5 cc (median, 0.31 cc). There was no association between NVB V100 or V150 and postimplantation impotency on actuarial analysis. Conclusion: Penile bulb doses are low after real-time ultrasound-guided prostate brachytherapy. We found no correlation between dose to either the penile bulb or NVBs and the development of postimplantation impotency.

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

    International Nuclear Information System (INIS)

    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.

  11. Agriculture-related radiation dose calculations

    International Nuclear Information System (INIS)

    Estimates of radiation dose to the public must be made at each stage in the identification and qualification process leading to siting a high-level nuclear waste repository. Specifically considering the ingestion pathway, this paper examines questions of reliability and adequacy of dose calculations in relation to five stages of data availability (geologic province, region, area, location, and mass balance) and three methods of calculation (population, population/food production, and food production driven). Calculations were done using the model PABLM with data for the Permian and Palo Duro Basins and the Deaf Smith County area. Extra effort expended in gathering agricultural data at succeeding environmental characterization levels does not appear justified, since dose estimates do not differ greatly; that effort would be better spent determining usage of food types that contribute most to the total dose; and that consumption rate and the air dispersion factor are critical to assessment of radiation dose via the ingestion pathway. 17 refs., 9 figs., 32 tabs

  12. Agriculture-related radiation dose calculations

    Energy Technology Data Exchange (ETDEWEB)

    Furr, J.M.; Mayberry, J.J.; Waite, D.A.

    1987-10-01

    Estimates of radiation dose to the public must be made at each stage in the identification and qualification process leading to siting a high-level nuclear waste repository. Specifically considering the ingestion pathway, this paper examines questions of reliability and adequacy of dose calculations in relation to five stages of data availability (geologic province, region, area, location, and mass balance) and three methods of calculation (population, population/food production, and food production driven). Calculations were done using the model PABLM with data for the Permian and Palo Duro Basins and the Deaf Smith County area. Extra effort expended in gathering agricultural data at succeeding environmental characterization levels does not appear justified, since dose estimates do not differ greatly; that effort would be better spent determining usage of food types that contribute most to the total dose; and that consumption rate and the air dispersion factor are critical to assessment of radiation dose via the ingestion pathway. 17 refs., 9 figs., 32 tabs.

  13. Comparative evaluation of two dose optimization methods for image-guided, highly-conformal, tandem and ovoids cervix brachytherapy planning

    Science.gov (United States)

    Ren, Jiyun; Menon, Geetha; Sloboda, Ron

    2013-04-01

    Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning—Nelder-Mead simplex (NMS) and simulated annealing (SA)—for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.

  14. MRI-Guided High–Dose-Rate Intracavitary Brachytherapy for Treatment of Cervical Cancer: The University of Pittsburgh Experience

    International Nuclear Information System (INIS)

    Purpose: Image-based brachytherapy is increasingly used for gynecologic malignancies. We report early outcomes of magnetic resonance imaging (MRI)-guided brachytherapy. Methods and Materials: Consecutive patient cases with FIGO stage IB1 to IVA cervical cancer treated at a single institution were retrospectively reviewed. All patients received concurrent cisplatin with external beam radiation therapy along with interdigitated high–dose-rate intracavitary brachytherapy. Computed tomography or MRI was completed after each application, the latter acquired for at least 1 fraction. High-risk clinical target volume (HRCTV) and organs at risk were identified by Groupe Européen de Curiethérapie and European SocieTy for Radiotherapy and Oncology guidelines. Doses were converted to equivalent 2-Gy doses (EQD2) with planned HRCTV doses of 75 to 85 Gy. Results: From 2007 to 2013, 128 patients, median 52 years of age, were treated. Predominant characteristics included stage IIB disease (58.6%) with a median tumor size of 5 cm, squamous histology (82.8%), and no radiographic nodal involvement (53.1%). Most patients (67.2%) received intensity modulated radiation therapy (IMRT) at a median dose of 45 Gy, followed by a median brachytherapy dose of 27.5 Gy (range, 25-30 Gy) in 5 fractions. At a median follow up of 24.4 months (range, 2.1-77.2 months), estimated 2-year local control, disease-free survival, and cancer-specific survival rates were 91.6%, 81.8%, and 87.6%, respectively. Predictors of local failure included adenocarcinoma histology (P<.01) and clinical response at 3 months (P<.01). Among the adenocarcinoma subset, receiving HRCTV D90 EQD2 ≥84 Gy was associated with improved local control (2-year local control rate 100% vs 54.5%, P=.03). Grade 3 or greater gastrointestinal or genitourinary late toxicity occurred at a 2-year actuarial rate of 0.9%. Conclusions: This study constitutes one of the largest reported series of MRI-guided brachytherapy in North

  15. MRI-Guided High–Dose-Rate Intracavitary Brachytherapy for Treatment of Cervical Cancer: The University of Pittsburgh Experience

    Energy Technology Data Exchange (ETDEWEB)

    Gill, Beant S.; Kim, Hayeon; Houser, Christopher J. [Department of Radiation Oncology, Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (United States); Kelley, Joseph L.; Sukumvanich, Paniti; Edwards, Robert P.; Comerci, John T.; Olawaiye, Alexander B.; Huang, Marilyn; Courtney-Brooks, Madeleine [Department of Gynecologic Oncology, Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (United States); Beriwal, Sushil, E-mail: beriwals@upmc.edu [Department of Radiation Oncology, Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (United States)

    2015-03-01

    Purpose: Image-based brachytherapy is increasingly used for gynecologic malignancies. We report early outcomes of magnetic resonance imaging (MRI)-guided brachytherapy. Methods and Materials: Consecutive patient cases with FIGO stage IB1 to IVA cervical cancer treated at a single institution were retrospectively reviewed. All patients received concurrent cisplatin with external beam radiation therapy along with interdigitated high–dose-rate intracavitary brachytherapy. Computed tomography or MRI was completed after each application, the latter acquired for at least 1 fraction. High-risk clinical target volume (HRCTV) and organs at risk were identified by Groupe Européen de Curiethérapie and European SocieTy for Radiotherapy and Oncology guidelines. Doses were converted to equivalent 2-Gy doses (EQD{sub 2}) with planned HRCTV doses of 75 to 85 Gy. Results: From 2007 to 2013, 128 patients, median 52 years of age, were treated. Predominant characteristics included stage IIB disease (58.6%) with a median tumor size of 5 cm, squamous histology (82.8%), and no radiographic nodal involvement (53.1%). Most patients (67.2%) received intensity modulated radiation therapy (IMRT) at a median dose of 45 Gy, followed by a median brachytherapy dose of 27.5 Gy (range, 25-30 Gy) in 5 fractions. At a median follow up of 24.4 months (range, 2.1-77.2 months), estimated 2-year local control, disease-free survival, and cancer-specific survival rates were 91.6%, 81.8%, and 87.6%, respectively. Predictors of local failure included adenocarcinoma histology (P<.01) and clinical response at 3 months (P<.01). Among the adenocarcinoma subset, receiving HRCTV D{sub 90} EQD{sub 2} ≥84 Gy was associated with improved local control (2-year local control rate 100% vs 54.5%, P=.03). Grade 3 or greater gastrointestinal or genitourinary late toxicity occurred at a 2-year actuarial rate of 0.9%. Conclusions: This study constitutes one of the largest reported series of MRI

  16. An automated optimization tool for high-dose-rate (HDR) prostate brachytherapy with divergent needle pattern

    Science.gov (United States)

    Borot de Battisti, M.; Maenhout, M.; de Senneville, B. Denis; Hautvast, G.; Binnekamp, D.; Lagendijk, J. J. W.; van Vulpen, M.; Moerland, M. A.

    2015-10-01

    Focal high-dose-rate (HDR) for prostate cancer has gained increasing interest as an alternative to whole gland therapy as it may contribute to the reduction of treatment related toxicity. For focal treatment, optimal needle guidance and placement is warranted. This can be achieved under MR guidance. However, MR-guided needle placement is currently not possible due to space restrictions in the closed MR bore. To overcome this problem, a MR-compatible, single-divergent needle-implant robotic device is under development at the University Medical Centre, Utrecht: placed between the legs of the patient inside the MR bore, this robot will tap the needle in a divergent pattern from a single rotation point into the tissue. This rotation point is just beneath the perineal skin to have access to the focal prostate tumor lesion. Currently, there is no treatment planning system commercially available which allows optimization of the dose distribution with such needle arrangement. The aim of this work is to develop an automatic inverse dose planning optimization tool for focal HDR prostate brachytherapy with needle insertions in a divergent configuration. A complete optimizer workflow is proposed which includes the determination of (1) the position of the center of rotation, (2) the needle angulations and (3) the dwell times. Unlike most currently used optimizers, no prior selection or adjustment of input parameters such as minimum or maximum dose or weight coefficients for treatment region and organs at risk is required. To test this optimizer, a planning study was performed on ten patients (treatment volumes ranged from 8.5 cm3to 23.3 cm3) by using 2-14 needle insertions. The total computation time of the optimizer workflow was below 20 min and a clinically acceptable plan was reached on average using only four needle insertions.

  17. Quality Control of High-Dose-Rate Brachytherapy: Treatment Delivery Analysis Using Statistical Process Control

    International Nuclear Information System (INIS)

    Purpose: Statistical process control (SPC) is a quality control method used to ensure that a process is well controlled and operates with little variation. This study determined whether SPC was a viable technique for evaluating the proper operation of a high-dose-rate (HDR) brachytherapy treatment delivery system. Methods and Materials: A surrogate prostate patient was developed using Vyse ordnance gelatin. A total of 10 metal oxide semiconductor field-effect transistors (MOSFETs) were placed from prostate base to apex. Computed tomography guidance was used to accurately position the first detector in each train at the base. The plan consisted of 12 needles with 129 dwell positions delivering a prescribed peripheral dose of 200 cGy. Sixteen accurate treatment trials were delivered as planned. Subsequently, a number of treatments were delivered with errors introduced, including wrong patient, wrong source calibration, wrong connection sequence, single needle displaced inferiorly 5 mm, and entire implant displaced 2 mm and 4 mm inferiorly. Two process behavior charts (PBC), an individual and a moving range chart, were developed for each dosimeter location. Results: There were 4 false positives resulting from 160 measurements from 16 accurately delivered treatments. For the inaccurately delivered treatments, the PBC indicated that measurements made at the periphery and apex (regions of high-dose gradient) were much more sensitive to treatment delivery errors. All errors introduced were correctly identified by either the individual or the moving range PBC in the apex region. Measurements at the urethra and base were less sensitive to errors. Conclusions: SPC is a viable method for assessing the quality of HDR treatment delivery. Further development is necessary to determine the most effective dose sampling, to ensure reproducible evaluation of treatment delivery accuracy

  18. Radiotherapy for stage III cervical cancer with high-dose rate brachytherapy

    International Nuclear Information System (INIS)

    This is a retrospective analysis of patients with histologically proven stage III cervical cancer with a minimum follow-up of 1.5 years at Keio University hospital between May 1973 and March 1991. Three hundred and sixty-six patients with stage III cervical cancer were classified into three groups according to the tumor size, those were, small (102 patients), medium (145 patients) and large (119 patients). All patients were treated with external irradiation (50 Gy) and high-dose rate intracavitary brachytherapy (20-34 Gy). The 5 year survival rate of all stage III patients was 47%. However, the survival gradient of small>medium>large was demonstrated and the differences between survival rates in each tumor size was significant. At follow-up visits conducted between 1 and 2 months after completion of radiation, 97 patients had physical findings of persistent disease. The larger the tumor size, the more likely was persistent disease by 2 months. The proportion of recurrent or regrowing tumors increased from small< medium< large. The difference between recurrent rates in patients with persistent tumor and without that was significant. There was no correlation between the incidence of metastasis in each tumor size and persistent disease. In patients with small or medium size tumors, there was no significant correlation between dose to these patients and pelvic tumor control. In large tumor, doses less than 24 Gy to point A resulted in higher pelvic failure and lower survival rate in contrast to doses of over 27 Gy. It was concluded that larger tumor or tumor that does not regress promptly is likely to recur. Such poor-prognosis patients should be targeted for early adjuvant or salvage therapy. (author)

  19. An automated optimization tool for high-dose-rate (HDR) prostate brachytherapy with divergent needle pattern.

    Science.gov (United States)

    Borot de Battisti, M; Maenhout, M; Denis de Senneville, B; Hautvast, G; Binnekamp, D; Lagendijk, J J W; van Vulpen, M; Moerland, M A

    2015-10-01

    Focal high-dose-rate (HDR) for prostate cancer has gained increasing interest as an alternative to whole gland therapy as it may contribute to the reduction of treatment related toxicity. For focal treatment, optimal needle guidance and placement is warranted. This can be achieved under MR guidance. However, MR-guided needle placement is currently not possible due to space restrictions in the closed MR bore. To overcome this problem, a MR-compatible, single-divergent needle-implant robotic device is under development at the University Medical Centre, Utrecht: placed between the legs of the patient inside the MR bore, this robot will tap the needle in a divergent pattern from a single rotation point into the tissue. This rotation point is just beneath the perineal skin to have access to the focal prostate tumor lesion. Currently, there is no treatment planning system commercially available which allows optimization of the dose distribution with such needle arrangement. The aim of this work is to develop an automatic inverse dose planning optimization tool for focal HDR prostate brachytherapy with needle insertions in a divergent configuration. A complete optimizer workflow is proposed which includes the determination of (1) the position of the center of rotation, (2) the needle angulations and (3) the dwell times. Unlike most currently used optimizers, no prior selection or adjustment of input parameters such as minimum or maximum dose or weight coefficients for treatment region and organs at risk is required. To test this optimizer, a planning study was performed on ten patients (treatment volumes ranged from 8.5 cm(3)to 23.3 cm(3)) by using 2-14 needle insertions. The total computation time of the optimizer workflow was below 20 min and a clinically acceptable plan was reached on average using only four needle insertions. PMID:26378657

  20. Quality assurance for high dose rate brachytherapy treatment planning optimization: using a simple optimization to verify a complex optimization

    International Nuclear Information System (INIS)

    As dose optimization for high dose rate brachytherapy becomes more complex, it becomes increasingly important to have a means of verifying that optimization results are reasonable. A method is presented for using a simple optimization as quality assurance for the more complex optimization algorithms typically found in commercial brachytherapy treatment planning systems. Quality assurance tests may be performed during commissioning, at regular intervals, and/or on a patient specific basis. A simple optimization method is provided that optimizes conformal target coverage using an exact, variance-based, algebraic approach. Metrics such as dose volume histogram, conformality index, and total reference air kerma agree closely between simple and complex optimizations for breast, cervix, prostate, and planar applicators. The simple optimization is shown to be a sensitive measure for identifying failures in a commercial treatment planning system that are possibly due to operator error or weaknesses in planning system optimization algorithms. Results from the simple optimization are surprisingly similar to the results from a more complex, commercial optimization for several clinical applications. This suggests that there are only modest gains to be made from making brachytherapy optimization more complex. The improvements expected from sophisticated linear optimizations, such as PARETO methods, will largely be in making systems more user friendly and efficient, rather than in finding dramatically better source strength distributions. (paper)

  1. Dose-volume histogram parameters of high-dose-rate brachytherapy for Stage I-II cervical cancer (≤4cm) arising from a small-sized uterus treated with a point A dose-reduced plan

    International Nuclear Information System (INIS)

    We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I-II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I-II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint ('point A dose-reduced plan') instead of the 6-Gy plan at point A ('tentative 6-Gy plan'). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control. (author)

  2. Calculation of external dose from distributed source

    International Nuclear Information System (INIS)

    This paper discusses a relatively simple calculational method, called the point kernel method (Fo68), for estimating external dose from distributed sources that emit photon or electron radiations. The principles of the point kernel method are emphasized, rather than the presentation of extensive sets of calculations or tables of numerical results. A few calculations are presented for simple source geometries as illustrations of the method, and references and descriptions are provided for other caluclations in the literature. This paper also describes exposure situations for which the point kernel method is not appropriate and other, more complex, methods must be used, but these methods are not discussed in any detail

  3. From reference air-kerma-rate to nominal absorbed dose-rate to water Paradigm shift in photon brachytherapy: ISO new work item proposal

    International Nuclear Information System (INIS)

    Full text: Over decades, photon radiation brachytherapy (BT) has proven worldwide as an essential modality of high precision radiation oncology for certain primary tumor sites. The dosimetric uncertainty of photon brachytherapy, however, is currently much larger than in external beam radiotherapy due to several factors including: calibration to the reference air-kerma-rate K.R K.R (or air-kerma strength), dose calculation model, dosimetric functions and dose measurement complexity, besides the geometrical dose uncertainties in high dose-gradient BT-fields. In addition, many photon sources are applied with quite different dosimetric properties requiring much skill from the medical physicist. This work proposes increased accuracy of brachytherapy through improvements in source calibration and clinical dosimetry methodology. Currently, BT-photon sources are calibrated free in air, at 100 cm distance, and in terms of K.R. By calibrating BT-photon sources directly to the TG-43U1 reference point at 1 cm in water, to be named the nominal absorbed dose-rate to water, D.w,1, the number of calibration steps in the traceability chain is reduced from 6 to 4, thus reducing the expanded uncertainty in dose delivery for patient treatment. With a target combined uncertainty of ucue.w,1 primary standards, which will soon become available for high energy and low energy, high and low dose-rate BT-photon sources. This is a paradigm shift that requires: international consensus, metrologic work and guidance. Thus, there is a need for an ISO standard based on and extending the AAPM TG-43U1 formalism. Taking into account the results and conclusions of the AAPM 2010 discussions, a draft for an ISO new work item proposal on Clinical dosimetry - Photon radiation sources for brachytherapy will be presented. This standardization project could be launched within ISO TC 85/SC 2/WG 22, in continuation of ISO 21439 (2009) for beta radiation sources. Clear terms and definitions are basic

  4. Dosimetric analysis of 3D image-guided HDR brachytherapy planning for the treatment of cervical cancer: is point A-based dose prescription still valid in image-guided brachytherapy?

    Science.gov (United States)

    Kim, Hayeon; Beriwal, Sushil; Houser, Chris; Huq, M Saiful

    2011-01-01

    The purpose of this study was to analyze the dosimetric outcome of 3D image-guided high-dose-rate (HDR) brachytherapy planning for cervical cancer treatment and compare dose coverage of high-risk clinical target volume (HRCTV) to traditional Point A dose. Thirty-two patients with stage IA2-IIIB cervical cancer were treated using computed tomography/magnetic resonance imaging-based image-guided HDR brachytherapy (IGBT). Brachytherapy dose prescription was 5.0-6.0 Gy per fraction for a total 5 fractions. The HRCTV and organs at risk (OARs) were delineated following the GYN GEC/ESTRO guidelines. Total doses for HRCTV, OARs, Point A, and Point T from external beam radiotherapy and brachytherapy were summated and normalized to a biologically equivalent dose of 2 Gy per fraction (EQD2). The total planned D90 for HRCTV was 80-85 Gy, whereas the dose to 2 mL of bladder, rectum, and sigmoid was limited to 85 Gy, 75 Gy, and 75 Gy, respectively. The mean D90 and its standard deviation for HRCTV was 83.2 ± 4.3 Gy. This is significantly higher (p IGBT in HDR cervical cancer treatment needs advanced concept of evaluation in dosimetry with clinical outcome data about whether this approach improves local control and/or decreases toxicities. PMID:20488690

  5. 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

    Energy Technology Data Exchange (ETDEWEB)

    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

  6. Dose calculations for intakes of ore dust

    International Nuclear Information System (INIS)

    This report describes a methodology for calculating the committed effective dose for mixtures of radionuclides, such as those which occur in natural radioactive ores and dusts. The formulae are derived from first principles, with the use of reasonable assumptions concerning the nature and behaviour of the radionuclide mixtures. The calculations are complicated because these 'ores' contain a range of particle sizes, have different degrees of solubility in blood and other body fluids, and also have different biokinetic clearance characteristics from the organs and tissues in the body. The naturally occurring radionuclides also tend to occur in series, i.e. one is produced by the radioactive decay of another 'parent' radionuclide. The formulae derived here can be used, in conjunction with a model such as LUDEP, for calculating total dose resulting from inhalation and/or ingestion of a mixture of radionuclides, and also for deriving annual limits on intake and derived air concentrations for these mixtures

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

    International Nuclear Information System (INIS)

    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)

  8. Assessment of cumulative external beam and intracavitary brachytherapy organ doses in gynecologic cancers using deformable dose summation

    International Nuclear Information System (INIS)

    Purpose: Due to inter-fraction variation in applicator position, organ displacement and deformation, doses to targets and normal tissues may not be accurately represented by adding the doses from external beam radiation therapy (EBRT) and intracavitary brachytherapy (ICBT) using rigid image registration. Deformable image registration permits organ and applicators to be spatially matched in 3D, enabling more accurate tracking of the accumulated volumetric dose to the target as well as organs at risk (OAR). This study assesses the dosimetric impact of using deformable image registration to determine the cumulative EBRT and ICBT doses to the rectum and bladder. Methods and materials: Data from 20 patients with stage IB1-IVA cervical cancer were analyzed. Nine of the patients were treated with ICBT and EBRT which included a nodal or parametrium boost while eleven were treated with ICBT and EBRT with no boost. Dose summation was performed in two stages. For the first stage, only the ICBT fractional doses were added using both “parameter adding” and deformable registration techniques. In the second stage, the ICBT and EBRT doses were combined using “parameter adding” in two ways. Partial “parameter adding” considers the cumulative ICBT dose from deformable registration as one parameter while full “parameter adding” uses fractional ICBT parameters. The cumulative minimum doses to 2cc (D2cc) of the rectum and bladder were compared between deformable registration and “parameter adding” techniques. Results: Dose summation of ICBT fractions only using deformable registration yielded D2cc values that were (10.1 ± 9.5)% lower for the rectum and (7.2 ± 6.3)% lower for the bladder compared to “parameter adding”. When ICBT and EBRT doses were summed deformably, the group without EBRT boost had D2cc that were (0.0 ± 4.6)% and (−1.2 ± 2.9)% lower for the rectum and bladder respectively compared to partial “parameter adding”. With EBRT boost, the

  9. A phantom study on bladder and rectum dose measurements in brachytherapy of cervix cancer using FBX aqueous chemical dosimeter.

    Science.gov (United States)

    Bansal, Anil K; Semwal, Manoj K; Arora, Deepak; Sharma, D N; Julka, P K; Rath, G K

    2013-06-01

    The ferrous sulphate-benzoic acid-xylenol orange (FBX) chemical dosimeter, due to its aqueous form can measure average volume doses and hence may overcome the limitations of point dosimetry. The present study was undertaken to validate the use of FBX dosimeter for rectum and bladder dose measurement during intracavitary brachytherapy (ICBT) and transperineal interstitial brachytherapy (TIB). We filled cylindrical polypropylene tubes (PT) and Foley balloons (FB) with FBX solution and used them as substitutes for rectum and bladder dose measurements respectively. A water phantom was fabricated with provision to place the Fletcher-type ICBT and MUPIT template applicators, and FBX filled PT and FB within the phantom. The phantom was then CT scanned for treatment planning and subsequent irradiation. Our results show that the average difference between DVH derived dose value and FBX measured dose is 3.5% (PT) and 13.7% (FB) for ICBT, and 9% (PT) and 9.9% (FB) for TIB. We believe that the FBX system should be able to provide accuracy and precision sufficient for routine quality assurance purposes. The advantage of the FBX system is its water equivalent composition, average volume dose measuring capability, and energy and temperature independent response as compared to TLD or semiconductor dosimeters. However, detailed studies will be needed with regards to its safety before actual in-vivo dose measurements are possible with the FBX dosimeter. PMID:22687710

  10. Dosimetric impact of applicator displacement during high dose rate (HDR) Cobalt-60 brachytherapy for cervical cancer: A planning study

    Science.gov (United States)

    Yong, J. S.; Ung, N. M.; Jamalludin, Z.; Malik, R. A.; Wong, J. H. D.; Liew, Y. M.; Ng, K. H.

    2016-02-01

    We investigated the dosimetric impact of applicator displacement on dose specification during high dose rate (HDR) Cobalt-60 (Co-60) brachytherapy for cervical cancer through a planning study. Eighteen randomly selected HDR full insertion plans were restrospectively studied. The tandem and ovoids were virtually shifted translationally and rotationally in the x-, y- and z-axis directions on the treatment planning system. Doses to reference points and volumes of interest in the plans with shifted applicators were compared with the original plans. The impact of dose displacement on 2D (point-based) and 3D (volume-based) treatment planning techniques was also assessed. A ±2 mm translational y-axis applicator shift and ±4° rotational x-axis applicator shift resulted in dosimetric changes of more than 5% to organs at risk (OAR) reference points. Changes to the maximum doses to 2 cc of the organ (D2cc) in 3D planning were statistically significant and higher than the reference points in 2D planning for both the rectum and bladder (p<0.05). Rectal D2cc was observed to be the most sensitive to applicator displacement among all dose metrics. Applicator displacement that is greater than ±2 mm translational y-axis and ±4° rotational x-axis resulted in significant dose changes to the OAR. Thus, steps must be taken to minimize the possibility of applicator displacement during brachytherapy.

  11. Post-operative high dose rate vaginal apex brachytherapy in stage I endometrial adenocarcinoma

    International Nuclear Information System (INIS)

    Purpose/Objective: Patients with Stage I endometrial adenocarcinoma have traditionally been treated with total abdominal hysterectomy/bilateral salpingo-oophorectomy and radiation. The reported incidence of local recurrence in surgically treated patients with FIGO Stage IA or IB endometrial adenocarcinoma is 4-10% at 2 years. Combined surgery and radiation has resulted in a reduction of recurrence to 2-6%. We report the presentation, actuarial survival, actuarial rate of local failure, salvage rate, and complications for patients undergoing high dose rate (HDR) vaginal apex brachytherapy following surgery. Materials and Methods: Between 1985 and 1994 a total of 286 patients with FIGO Stage I endometrioid uterine adenocarcinoma were treated with HDR Ir-192 vaginal apex brachytherapy alone to a total dose of 21 Gy in 3 fractions at 0.5 cm from the vaginal mucosa. The pathologic stage by treatment group was IA: 31%, IB: 68%, and IC: 1%. The histologic grade of the patient's tumors was grade 1: 69%, 2: 29%, and 3: 2% of patients. The median time from surgery to radiation was 34 days (range 14-66 days). The median follow-up for 286 patients with Stage IA (92 patients), IB (190 patients), and IC (4 patients) was respectively, 37, 35 and 40 months (2 patients lost to follow-up prior to 6 months). Results: Patients presented with vaginal bleeding (94%) or abnormal pap smear (6%) at a median age for Stage IA and IB, of 54 and 63 years, respectively (range 32-88). The 5-year overall actuarial survival rate was 94.5%. The 5-year actuarial survival rate by histologic grade was 97.5% and 91.5% for FIGO grade 1 and 2, respectively (p=.011). The 5-year actuarial survival rate by depth of myometrial invasion was 99.0% and 92.5% for Stage IA and IB, respectively (p=.029). Median overall time to failure is 19.5 months (range 10-36 months). The 5-year actuarial rate of local failure was 4.5%. The overall failure rate in our study group was 2.8% (8 patients), local failure only 1

  12. Postoperative high dose rate vaginal apex brachytherapy in stage I endometrial adenocarcinoma

    International Nuclear Information System (INIS)

    Introduction: Patients with stage I endometrial adenocarcinoma have traditionally been treated with TAH/BSO and radiation. The reported incidence of local recurrence in surgically treated patients with Figo stage IA or IB endometrial adenocarcinoma is 4-10% at 2 years. Combined surgery and radiation has resulted in a reduction of recurrence to 2-6%. We report the presentation, local and distant control, salvage rate, survival and complications for patients undergoing high dose rate (HDR) vaginal apex brachytherapy following surgery. Methods: Between 1985 and 1994 a total of 302 patients with Figo stage I endometrial carcinoma were treated with HDR Ir-192 vaginal apex brachytherapy to a total dose of 21 Gy in 3 fractions at 0.5 cm from the vaginal mucosa. The pathologic stage by treatment group was IA: 31%, IB: 68%, and IC: 1%. The histologic grade of the patient's tumors was grade 1: 69%, 2: 27%, and 3: 4%. The median time from surgery to radiation was 33 days (range 14-66 days). The median follow-up for 300 patients with stage IA (91 patients), IB (205 patients), and IC (4 patients) was respectively 36, 34 and 40 months (2 patients lost to follow-up prior to 6 months). Results: Patients presented with vaginal bleeding (94%) or abnormal pap smear (6%) at a median age for stage IA and IB, of 55 and 64 years, respectively. The crude overall survival of the patient population at 2 years is 95%. Median overall time to failure is 19.5 months (range 10-36 months). The overall failure rate was 2.7% (8 patients), local failure only 1.0% (38% of failed group), distant failure only 0.3% (12% of failed group) and combined local/distant failure 1.3% (50% of failed group). The local failure rate for pathologic stage IA patients was 1.0% and no distant disease was observed. The local failure rate for pathologic stage IB patients was 3.4% 7/205 and distant failure was 2.4% 5/205. The majority of patients with recurrence had grade 2 histologic changes 5/8. The overall salvage rate

  13. The incidence of radioepidermitis and the dose-response relationship in parotid gland cancer patients treated with 125I seed brachytherapy. Incidence of radioepidermitis and the dose-response relationship

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Ming-Hui; Zheng, Lei; Gao, Hong; Zhang, Jie; Liu, Shu-ming; Huang, Ming-wei; Shi, Yan [Peking University School and Hospital of Stomatology, Department of Oral and Maxillofacial Surgery, Beijing (China); Zhang, Jian-Guo [Peking University School and Hospital of Stomatology, Department of Oral and Maxillofacial Surgery, Beijing (China); Fujian Provincial Hospital, Fujian (China)

    2014-09-09

    We studied the incidence and dose-response relationship of radioepidermitis in parotid gland carcinoma patients treated with [{sup 125}I] seed brachytherapy in the hopes of designing an optimized pre-implant treatment plan that would reduce the incidence and severity of radioepidermitis in patients receiving this therapy. Between January 2007 and May 2010, 100 parotid gland cancer patients were treated postoperatively with [{sup 125}I] seed brachytherapy. The matched peripheral dose (MPD) was 80-140 Gy, and [{sup 125}I] seed activity was 0.7-0.8 mCi. The mean dose delivered to the skin was calculated in the post-implant CT on day 0 following implantation. Grades of acute and late dermatitis were evaluated at 2, 6, 12, and 18 months post-implantation. Most patients experienced grade 0-2 acute and late skin side effects (86 and 97 %, respectively), though a small subset developed severe complications. Most grade 1-3 effects resolved within 6 months of implantation, though some grade 1-3 effects and all grade 4 effects remained unchanged throughout the 18-month follow-up period. Grade 3 and 4 effects were most prominent (75 and 25 %, respectively) with doses of 110-140 Gy; doses higher than 140 Gy produced only grade 4 effects. [{sup 125}I] seed brachytherapy produced acceptable levels of acute and late radioepidermitis with a good clinical outcome. A mean dose under 100 Gy delivered to the skin was safe, though doses of 110-140 Gy should be given with caution and extra monitoring; doses greater than 140 Gy are dangerous and likely to produce grade 4-5 effects. (orig.) [German] Wir untersuchten die Inzidenz und die Dosis-Wirkung-Beziehung bei Patienten mit Ohrspeicheldruesenkrebs, die mit [{sup 125}I]-Seed-Brachytherapie behandelt wurden, in der Hoffnung, eine optimierte praeimplantologische Behandlung zu entwickeln, welche die Inzidenz und Schwere der Radioepidermitis bei Patienten, die diese Therapie erhalten haben, reduziert. Zwischen Januar 2007 und Mai 2010

  14. High-dose rate brachytherapy in localized penile cancer: short-term clinical outcome analysis

    International Nuclear Information System (INIS)

    To assess clinical outcomes of high-dose rate interstitial brachytherapy (HIB) in localized penile carcinoma. From 03/2006 to 08/2013, patients with biopsy-proven T1-T2 (<4 cm) non-metastatic localized penile squamous cell carcinoma underwent HIB. Under general anaesthesia, after Foley catheter placement, needles were placed in the target volume using a dedicated template. Planification was carried out with a post-implant CT-scan to deliver a total dose of 36 Gy in 9 fractions over 5 days (in adjuvant setting) or 39 Gy in 9 fractions over 5 days (as monotherapy). Dose-volume adaptation was manually achieved using graphical optimization. Dosimetric data and clinical outcomes were retrospectively analyzed. Toxicities were graded using the CTC v4.0. With a median follow-up of 27 months [5.1-83], 12 patients including 8 T1a, 3 T1b and 1 T2 N0 underwent HIB (sole therapy: 11 pts; adjuvant: 1 pt). The actuarial 5-year relapse-free, cause-specific and overall survival rates were 83%, 100% and 78% respectively. Comparing pre and post treatment evaluation, no IPSS or IIEF-5 changes were reported. Dermatitis was reported systematically 1 month after HIB including 6 G1, 5 G2 and 1 G3. Only 1 experienced long-term G3 successfully treated with hyperbaric oxygen therapy. One urethral meatus stenosis G3 required meatotomy. In selected patients with T1-T2 localized penile cancer, HIB may be considered as an optional conservative therapy. Longer follow-up is needed to confirm these encouraging preliminary results

  15. SU-E-J-93: Parametrisation of Dose to the Mucosa of the Anterior Rectal Wall in Transrectal Ultrasound Guided High-Dose-Rate Brachytherapy of the Prostate

    Energy Technology Data Exchange (ETDEWEB)

    Aitkenhead, A; Hamlett, L; Wood, D; Choudhury, A [The Christie Hospital NHS Foundation Trust, Manchester, Greater Manchester (United Kingdom)

    2014-06-01

    Purpose: In high-dose-rate (HDR) brachytherapy of the prostate, radiation is delivered from a number of radioactive sources which are inserted via catheter into the target volume. The rectal mucosa also receives dose during the treatment, which may lead to late toxicity effects. To allow possible links between rectal dose and toxicity to be investigated, suitable methods of parametrising the rectal dose are needed. Methods: During treatment of a series of 95 patients, anatomy and catheter locations were monitored by transrectal ultrasound, and target volume positions were contoured on the ultrasound scan by the therapist. The anterior rectal mucosal wall was identified by contouring the transrectal ultrasound balloon within the ultrasound scan. Source positions and dwell times, along with the dose delivered to the patient were computed using the Oncentra Prostate treatment planning system (TPS). Data for the series of patients were exported from the TPS in Dicom format, and a series of parametrisation methods were developed in a Matlab environment to assess the rectal dose. Results: Contours of the anterior rectal mucosa were voxelised within Matlab to allow the dose to the rectal mucosa to be analysed directly from the 3D dose grid. Dose parametrisations based on dose-surface (DSH) and dose-line (DLH) histograms were obtained. Both lateral and longitudinal extents of the mucosal dose were parametrised using dose-line histograms in the relevant directions. Conclusion: We have developed a series of dose parametrisations for quantifying the dose to the rectal mucosa during HDR prostate brachytherapy which are suitable for future studies investigating potential associations between mucosal dose and late toxicity effects. The geometry of the transrectal probe standardises the rectal anatomy, making this treatment technique particularly suited to studies of this nature.

  16. SU-E-J-93: Parametrisation of Dose to the Mucosa of the Anterior Rectal Wall in Transrectal Ultrasound Guided High-Dose-Rate Brachytherapy of the Prostate

    International Nuclear Information System (INIS)

    Purpose: In high-dose-rate (HDR) brachytherapy of the prostate, radiation is delivered from a number of radioactive sources which are inserted via catheter into the target volume. The rectal mucosa also receives dose during the treatment, which may lead to late toxicity effects. To allow possible links between rectal dose and toxicity to be investigated, suitable methods of parametrising the rectal dose are needed. Methods: During treatment of a series of 95 patients, anatomy and catheter locations were monitored by transrectal ultrasound, and target volume positions were contoured on the ultrasound scan by the therapist. The anterior rectal mucosal wall was identified by contouring the transrectal ultrasound balloon within the ultrasound scan. Source positions and dwell times, along with the dose delivered to the patient were computed using the Oncentra Prostate treatment planning system (TPS). Data for the series of patients were exported from the TPS in Dicom format, and a series of parametrisation methods were developed in a Matlab environment to assess the rectal dose. Results: Contours of the anterior rectal mucosa were voxelised within Matlab to allow the dose to the rectal mucosa to be analysed directly from the 3D dose grid. Dose parametrisations based on dose-surface (DSH) and dose-line (DLH) histograms were obtained. Both lateral and longitudinal extents of the mucosal dose were parametrised using dose-line histograms in the relevant directions. Conclusion: We have developed a series of dose parametrisations for quantifying the dose to the rectal mucosa during HDR prostate brachytherapy which are suitable for future studies investigating potential associations between mucosal dose and late toxicity effects. The geometry of the transrectal probe standardises the rectal anatomy, making this treatment technique particularly suited to studies of this nature

  17. TLD skin dose measurements and acute and late effects after lumpectomy and high-dose-rate brachytherapy only for early breast cancer

    International Nuclear Information System (INIS)

    Purpose: This report examines the relationships between measured skin doses and the acute and late skin and soft tissue changes in a pilot study of lumpectomy and high-dose-rate brachytherapy only for breast cancer. Methods and Materials: Thirty-seven of 39 women enrolled in this pilot study of high-dose-rate brachytherapy (37.2 Gy in 10 fractions b.i.d.) each had thermoluminescent dosimetry (TLD) at 5 points on the skin of the breast overlying the implant volume. Skin changes at TLD dose points and fibrosis at the lumpectomy site were documented every 6 to 12 months posttreatment using a standardized physician-rated cosmesis questionnaire. The relationships between TLD dose and acute skin reaction, pigmentation, or telangiectasia at 5 years were analyzed using the GEE algorithm and the GENMOD procedure in the SAS statistical package. Fisher's exact test was used to determine whether there were any significant associations between acute skin reaction and late pigmentation or telangiectasia or between the volumes encompassed by various isodoses and fibrosis or fat necrosis. Results: The median TLD dose per fraction (185 dose points) multiplied by 10 was 9.2 Gy. In all 37 patients, acute skin reaction Grade 1 or higher was observed at 5.9% (6 of 102) of dose points receiving 10 Gy or less vs. 44.6% (37 of 83) of dose points receiving more than 10 Gy (p 3 or less covered by the 100% isodose vs. 83.3% (5 of 6) of patients with a larger volume (p 0.180). Asymptomatic and biopsy-proven fat necrosis occurred in 5 patients. No significant differences in fat necrosis rates according to volume were detected. Conclusions: For high-dose-rate brachytherapy to the lumpectomy site, TLD skin dose was significantly related to acute skin reaction and to pigmentation and telangiectasia at 60 months. An acute skin reaction was also significantly associated with the development of telangiectasia at 60 months. TLD skin dose measurement may allow modification of the brachytherapy implant

  18. High-dose rate brachytherapy in the treatment of prostate cancer: acute toxicity and biochemical behavior analysis

    International Nuclear Information System (INIS)

    Objective: this study focuses on the biochemical response of the following variables: prostate volume, prostate-specific antigen (PSA) value, Gleason scores, staging, the risk of the disease, and hormone therapy. Objective: in the period between February of 1998 and July of 2001, 46 patients with prostate cancer were treated with radiotherapy, in a combination of teletherapy and high-dose rate (HDR) brachytherapy. The age ranged from 51 to 79 years (averaging 66.4 years). T1c stage was the most frequent one: 30 (65%). The Gleason score was below 7 in 78% of the patients. PSA ranged from 3.4 to 33.3, being below 10 in 39% of the cases. The average prostatic volume was 32.3 cc. Twenty-eight percent of the patients received hormone therapy. Teletherapy dose ranged from 45 to 50.4 Gy, associated to four fractions of 4 Gy of HDR brachytherapy. Results: the follow-up period varied from 6 to 43 months. Four patients missed the follow-up and four died (one due to the disease). Out of the 39 patients that were analyzed, 76% presented a less than 1.5 PSA. None of the analyzed variables were found to be of statistical significance (p > 0.05) regarding biochemical control. Conclusion: the use of HDR brachytherapy was found to be effective in the treatment of prostate cancer and, in this study, the variables considered as prognostic factors did not interfere in the biochemical control. (author)

  19. Towards enabling ultrasound guidance in cervical cancer high-dose-rate brachytherapy

    Science.gov (United States)

    Wong, Adrian; Sojoudia, Samira; Gaudet, Marc; Yap, Wan Wan; Chang, Silvia D.; Abolmaesumi, Purang; Aquino-Parsons, Christina; Moradi, Mehdi

    2014-03-01

    MRI and Computed Tomography (CT) are used in image-based solutions for guiding High Dose Rate (HDR) brachytherapy treatment of cervical cancer. MRI is costly and CT exposes the patients to ionizing radiation. Ultrasound, on the other hand, is affordable and safe. The long-term goal of our work is to enable the use of multiparametric ultrasound imaging in image-guided HDR for cervical cancer. In this paper, we report the development of enabling technology for ultrasound guidance and tissue typing. We report a system to obtain the 3D freehand transabdominal ultrasound RF signals and B-mode images of the uterus, and a method for registration of ultrasound to MRI. MRI and 3D ultrasound images of the female pelvis were registered by contouring the uterus in the two modalities, creating a surface model, followed by rigid and B-spline deformable registration. The resulting transformation was used to map the location of the tumor from the T2-weighted MRI to ultrasound images and to determine cancerous and normal areas in ultrasound. B-mode images show a contrast for cancer vs. normal tissue. Our study shows the potential and the challenges of ultrasound imaging in guiding cervical cancer treatments.

  20. High-dose-rate brachytherapy for soft tissue sarcoma in children: a single institution experience

    International Nuclear Information System (INIS)

    To report our experience treating soft tissue sarcoma (STS) with high dose rate brachytherapy alone (HBRT) or in combination with external beam radiotherapy (EBRT) in pediatric patients. Eighteen patients, median age 11 years (range 2 – 16 years) with grade 2–3 STS were treated with HBRT using Ir-192 in a interstitial (n = 14) or intracavitary implant (n = 4). Eight patients were treated with HBRT alone; the remaining 10 were treated with a combination of HBRT and EBRT. After a median follow-up of 79.5 months (range 12 – 159), 14 patients were alive and without evidence of disease (5-year overall survival rate 84.5%). There were no local or regional failures in the group treated with HBRT alone. One patient developed distant metastases at 14 months and expired after 17 months. In the combined HBRT and EBRT group, there was 1 local failure (22 months), and 3 patients developed pulmonary metastatic disease 18, 38 and 48 months after diagnosis and no these patients were alive at the time of this report. The overall local control to HBRT alone and HBRT plus EBRT were 100 and 90%, respectively. The acute affects most common were local erythema and wound dehiscence in 6 (33%) and 4 (22%) patients. Late effects were observed in 3 patients (16.5%). Excellent local control with tolerable side effects have been observed in a small group of paediatric patients with STS treated by HBRT alone or in combination with EBRT

  1. Long-term results of curative intraluminal high dose rate brachytherapy for endobronchial carcinoma

    International Nuclear Information System (INIS)

    The treatment strategy of central lung tumors is not established. Intraluminal brachytherapy (ILBT) is widely used for palliative treatment of endobronchial tumors, however, it is also a promising option for curative treatment with limited data. This study evaluates the results after ILBT for endobronchial carcinoma. Sixteen-endobronchial carcinoma of 13 patients treated with ILBT in curative intent for 2000 to 2008 were retrospectively reviewed. ILBT using high dose rate 192 iridium thin wire system was performed with 5 Gy/fraction at mucosal surface. The patient age ranged from 57 to 82 years old with median 75 years old. The 16 lesions consisted of 13 central endobronchial cancers including 7 roentgenographically occult lung cancers and 3 of tracheal cancers. Of them, 10 lesions were treated with ILBT of median 20 Gy combined with external beam radiation therapy of median 45 Gy and 6 lesions were treated with ILBT alone of median 25 Gy. Median follow-up time was 32.5 months. Two-year survival rate and local control rate were 92.3% and 86.2%, respectively. Local recurrences were observed in 2 lesions. Three patients died due to lung cancer (1 patient) and intercurrent disease (2 patients). Complications greater than grade 2 were not observed except for one grade 3 dyspnea. ILBT combined with or without EBRT might be a curative treatment option in inoperable endobronchial carcinoma patients with tolerable complication

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

    International Nuclear Information System (INIS)

    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

    International Nuclear Information System (INIS)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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

  6. 3D-image-guided high-dose-rate intracavitary brachytherapy for salvage treatment of locally persistent nasopharyngeal carcinoma

    OpenAIRE

    Ren, Yu-Feng; Cao, Xin-Ping; Xu, Jia; Ye, Wei-Jun; Gao, Yuan-Hong; Teh, Bin S.; Wen, Bi-Xiu

    2013-01-01

    Background To evaluate the therapeutic benefit of 3D-image-guided high-dose-rate intracavitary brachytherapy (3D-image-guided HDR-BT) used as a salvage treatment of intensity modulated radiation therapy (IMRT) in patients with locally persistent nasopharyngeal carcinoma (NPC). Methods Thirty-two patients with locally persistent NPC after full dose of IMRT were evaluated retrospectively. 3D-image-guided HDR-BT treatment plan was performed on a 3D treatment planning system (PLATO BPS 14.2). The...

  7. Simple DVH parameter addition as compared to deformable registration for bladder dose accumulation in cervix cancer brachytherapy

    DEFF Research Database (Denmark)

    Andersen, Else Stougård; Noe, Karsten Østergaaard; Sørensen, Thomas Sangild; Nielsen, Søren Kynde; LU, Fokdal; Paludan, Merete; Lindegaard, Jacob Christian; Tanderup, Kari

    2013-01-01

    Background and purpose: Variations in organ position, shape, and volume cause uncertainties in dose assessment for brachytherapy (BT) in cervix cancer. The purpose of this study was to evaluate uncertainties associated with bladder dose accumulation based on DVH parameter addition (previously...... called "the worst case assumption") in fractionated BT. Materials and methods: Forty-seven patients treated for locally advanced cervical cancer were included. All patients received EBRT combined with two individually planned 3D image-guided adaptive BT fractions. D2 and D0.1 were estimated by DVH...

  8. Recommendations for Insulin Dose Calculator Risk Management

    OpenAIRE

    Rees, Christen

    2014-01-01

    Several studies have shown the usefulness of an automated insulin dose bolus advisor (BA) in achieving improved glycemic control for insulin-using diabetes patients. Although regulatory agencies have approved several BAs over the past decades, these devices are not standardized in their approach to dosage calculation and include many features that may introduce risk to patients. Moreover, there is no single standard of care for diabetes worldwide and no guidance documents for BAs, specificall...

  9. Postoperative Nomogram Predicting the 9-Year Probability of Prostate Cancer Recurrence After Permanent Prostate Brachytherapy Using Radiation Dose as a Prognostic Variable

    International Nuclear Information System (INIS)

    Purpose: To report a multi-institutional outcomes study on permanent prostate brachytherapy (PPB) to 9 years that includes postimplant dosimetry, to develop a postimplant nomogram predicting biochemical freedom from recurrence. Methods and Materials: Cox regression analysis was used to model the clinical information for 5,931 patients who underwent PPB for clinically localized prostate cancer from six centers. The model was validated against the dataset using bootstrapping. Disease progression was determined using the Phoenix definition. The biological equivalent dose was calculated from the minimum dose to 90% of the prostate volume (D90) and external-beam radiotherapy dose using an α/β of 2. Results: The 9-year biochemical freedom from recurrence probability for the modeling set was 77% (95% confidence interval, 73-81%). In the model, prostate-specific antigen, Gleason sum, isotope, external beam radiation, year of treatment, and D90 were associated with recurrence (each p < 0.05), whereas clinical stage was not. The concordance index of the model was 0.710. Conclusion: A predictive model for a postimplant nomogram for prostate cancer recurrence at 9-years after PPB has been developed and validated from a large multi-institutional database. This study also demonstrates the significance of implant dosimetry for predicting outcome. Unique to predictive models, these nomograms may be used a priori to calculate a D90 that likely achieves a desired outcome with further validation. Thus, a personalized dose prescription can potentially be calculated for each patient.

  10. Treatment outcome with low-dose-rate interstitial brachytherapy in early-stage oral tongue cancers

    Directory of Open Access Journals (Sweden)

    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.

  11. Preliminary report of pulsed dose rate brachytherapy in head-and-neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ziemlewski, A.; Zienkiewicz, J. [Medical Univ. of Gdansk (Poland). Dept. of Oral and Maxillofacial Surgery; Serkies, K.; Badzio, A. [Medical Univ. of Gdansk (Poland). Dept. of Oncology and Radiotherapy

    2007-09-15

    Purpose: To assess the feasibility and acute/delayed toxicity of pulsed-dose-rate brachytherapy (PDR BT) in head-and-neck tumors. Patients and Methods: 45 head and neck cancer patients underwent interstitial or contact PDR BT at a dose of 10.2-70 Gy (median, 70 Gy) and 0.6 or 1.0 Gy/pulse/h. 42 patients were administered BT as part of their curative treatment; 32 of them had sole BT. Three reirradiated patients with recurrent tumor had palliative BT. Results: PDR BT was well tolerated. Intense bleeding was the only complication associated with catheter removal from the tongue and bucca. 44 patients who completed BT experienced acute mucositis. Grade 3 toxicity of skin and oral mucosa occurred in three (6.8%) and six patients (13.6%), respectively. At a median follow-up of 22 months (range, 2-67 months), late serious toxicity (grade 4, for soft tissue and bone) was seen in seven patients (15.9%). Among the parameters analyzed, only dental care performed before BT had a significant impact on mucosal side effects. Acute severe mucositis was observed in 23% of patients without dental care compared to 0% of those with dental care (p = 0.044). Late severe mucositis occurred in 17.7% and 26.9% of the respective patients (p = 0.035), overall in 23%. The larger the volume encompassed by the reference isodose, the more late (p = 0.004) mucosal reactions were observed. Conclusion: PDR BT continued over a few days is a feasible and safe approach in head-and-neck tumors; however, it is accompanied by some toxicity. Dental care should precede isotope application. (orig.)

  12. High dose-rate brachytherapy as a treatment option in primary tracheal tumors Braquiterapia de alta taxa de dose como opção terapêutica nos tumores primários da traquéia

    Directory of Open Access Journals (Sweden)

    Heloisa de Andrade Carvalho

    2005-08-01

    Full Text Available PURPOSE: To present experience with high dose-rate endobronchial brachytherapy in the treatment of primary tracheal tumors. PATIENTS AND METHODS: Four patients with nonresected primary tracheal tumors are presented: 2 cases of squamous cell carcinoma of the trachea, 1 of recurrent adenoid cystic carcinoma, and 1 with recurrent plasmacytoma. All received brachytherapy, alone or as a boost for primary irradiation, in 3 or 4 fractions of 7.5 Gy, calculated at a depth of 1 cm. Follow-up was considered to start from the end of brachytherapy. RESULTS: Local control was achieved in all cases at the time of first bronchoscopic evaluation. Two patients with squamous cell carcinoma died at 6th and 33rd months after brachytherapy, respectively. The first had no evidence of disease, and the latter had local recurrence. The other 2 patients were alive after 64 and 110 months of follow-up, respectively, both with no evidence of disease. Tracheal stenosis developed in these 2 cases, 22 and 69 months after brachytherapy. Tracheal stent placement was needed only for the patient with an adenoid cystic carcinoma. CONCLUSIONS: Endobronchial high dose-rate brachytherapy may be used for tracheal tumors, even as a boost for external beam irradiation, or in recurrences. Local control in 3 out of 4 patients indicates that individual cases may benefit from the treatment. Long-term survival may also be expected, mainly for tumors with adenoid cystic histology.OBJETIVO: Apresentar a experiência do tratamento de 4 pacientes com tumores primários de traquéia, não operados, submetidos à braquiterapia endobrônquica de alta taxa de dose. PACIENTES E MÉTODOS: Dois casos de carcinoma espinocelular, uma recidiva de carcinoma adenóide cístico e uma recidiva de plasmocitoma primário da traquéia. Todos receberam braquiterapia endobrônquica, exclusiva ou como reforço de dose da radioterapia externa. Foram administradas 3 ou 4 frações de 7,5 Gy cada, calculados a 1 cm de

  13. SU-E-J-116: Uncertainties Associated with Dose Summation of High-Dose Rate Brachytherapy and Intensity Modulated Radiotherapy for Gynecological Cases

    International Nuclear Information System (INIS)

    Purpose: Determining the cumulative dose distribution (CDD) for gynecological patients treated with both high-dose rate (HDR) brachytherapy and intensity-modulated radiotherapy (IMRT) is challenging. The purpose of this work is to study the uncertainty of performing this with a structure-guided deformable (SGD) approach in Velocity. Methods: For SGD, the Hounsfield units inside specified contours are overridden to set uniform values. Deformable image registration (DIR) is the run on these process images, which forces the DIR to focus on these contour boundaries. 18 gynecological cancer patients were used in this study. The original bladder and rectum planning contours for these patients were used to drive the SGD. A second set of contours were made of the bladder by the same person with the intent of carefully making them completely consistent with each other. This second set was utilized to evaluate the spatial accuracy of the SGD. The determined spatial accuracy was then multiplied by the local dose gradient to determine a dose uncertainty associated with the SGD dose warping. The normal tissue complication probability (NTCP) was then calculated for each dose volume histogram (DVH) that included four different probabilistic uncertainties associated with the spatial errors (e.g., 68.3% and 95.4%). Results: The NTCPs for each DVH (e.g., NTCP-−95.4%, NTCP-−68.3%, NTCP-68.3%, NTCP-95.4%) differed amongst patients. All patients had an NTCP-−95.4% close to 0%, while NTCP-95.4% ranged from 0.67% to 100%. Nine patients had an NTCP-−95.4% less than 50% while the remaining nine patients had NTCP-95.4% greater than 50%. Conclusion: The uncertainty associated with this CDD technique renders a large NTCP uncertainty. Thus, it is currently not practical for clinical use. The two ways to improve this would be to use more precise contours to drive the SGD and to use a more accurate DIR algorithm

  14. SU-E-J-116: Uncertainties Associated with Dose Summation of High-Dose Rate Brachytherapy and Intensity Modulated Radiotherapy for Gynecological Cases

    Energy Technology Data Exchange (ETDEWEB)

    Kauweloa, K; Bergamo, A; Gutierrez, A; Stathakis, S; Papanikolaou, N; Kirby, N [University of Texas HSC SA, San Antonio, TX (United States); Cancer Therapy and Research Center, San Antonio, TX (United States); Mavroidis, P [University of North Carolina, Chapel Hill, NC (United States)

    2015-06-15

    Purpose: Determining the cumulative dose distribution (CDD) for gynecological patients treated with both high-dose rate (HDR) brachytherapy and intensity-modulated radiotherapy (IMRT) is challenging. The purpose of this work is to study the uncertainty of performing this with a structure-guided deformable (SGD) approach in Velocity. Methods: For SGD, the Hounsfield units inside specified contours are overridden to set uniform values. Deformable image registration (DIR) is the run on these process images, which forces the DIR to focus on these contour boundaries. 18 gynecological cancer patients were used in this study. The original bladder and rectum planning contours for these patients were used to drive the SGD. A second set of contours were made of the bladder by the same person with the intent of carefully making them completely consistent with each other. This second set was utilized to evaluate the spatial accuracy of the SGD. The determined spatial accuracy was then multiplied by the local dose gradient to determine a dose uncertainty associated with the SGD dose warping. The normal tissue complication probability (NTCP) was then calculated for each dose volume histogram (DVH) that included four different probabilistic uncertainties associated with the spatial errors (e.g., 68.3% and 95.4%). Results: The NTCPs for each DVH (e.g., NTCP-−95.4%, NTCP-−68.3%, NTCP-68.3%, NTCP-95.4%) differed amongst patients. All patients had an NTCP-−95.4% close to 0%, while NTCP-95.4% ranged from 0.67% to 100%. Nine patients had an NTCP-−95.4% less than 50% while the remaining nine patients had NTCP-95.4% greater than 50%. Conclusion: The uncertainty associated with this CDD technique renders a large NTCP uncertainty. Thus, it is currently not practical for clinical use. The two ways to improve this would be to use more precise contours to drive the SGD and to use a more accurate DIR algorithm.

  15. The evolution of brachytherapy treatment planning

    International Nuclear Information System (INIS)

    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.

  16. The evolution of brachytherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Phantoms for calculations of absorbed organ dose

    International Nuclear Information System (INIS)

    We have developed a computer code IDES (Internal Dose Estimation System). In this code, MIRD Transformation Method is used and photon simulation by Monte Carlo method is also possible. We have studied Japanese phantoms in two procedures, mathematical phantom and 'symbol phantoms'. Our mathematical phantoms realize their height and body weights but does not hold some of organ weights, which were measured by TANAKA and KAWAMURA. The symbol phantom can solve this discrepancy and realize a realistic phantom, although it remains problems of authorization and normalization. Errors were estimated for internal dose calculations and it was pointed out that to use realistic organ weights and parameters of kinetics was important competitively to reduce uncertainty of the results. (author)

  18. Poster — Thur Eve — 40: Automated Quality Assurance for Remote-Afterloading High Dose Rate Brachytherapy

    International Nuclear Information System (INIS)

    High dose rate (HDR) remote afterloading brachytherapy involves sending a small, high-activity radioactive source attached to a cable to different positions within a hollow applicator implanted in the patient. It is critical that the source position within the applicator and the dwell time of the source are accurate. Daily quality assurance (QA) tests of the positional and dwell time accuracy are essential to ensure that the accuracy of the remote afterloader is not compromised prior to patient treatment. Our centre has developed an automated, video-based QA system for HDR brachytherapy that is dramatically superior to existing diode or film QA solutions in terms of cost, objectivity, positional accuracy, with additional functionalities such as being able to determine source dwell time and transit time of the source. In our system, a video is taken of the brachytherapy source as it is sent out through a position check ruler, with the source visible through a clear window. Using a proprietary image analysis algorithm, the source position is determined with respect to time as it moves to different positions along the check ruler. The total material cost of the video-based system was under $20, consisting of a commercial webcam and adjustable stand. The accuracy of the position measurement is ±0.2 mm, and the time resolution is 30 msec. Additionally, our system is capable of robustly verifying the source transit time and velocity (a test required by the AAPM and CPQR recommendations), which is currently difficult to perform accurately

  19. Poster — Thur Eve — 40: Automated Quality Assurance for Remote-Afterloading High Dose Rate Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Anthony; Ravi, Ananth [Sunnybrook Health Sciences Centre/Odette Cancer Centre (Canada)

    2014-08-15

    High dose rate (HDR) remote afterloading brachytherapy involves sending a small, high-activity radioactive source attached to a cable to different positions within a hollow applicator implanted in the patient. It is critical that the source position within the applicator and the dwell time of the source are accurate. Daily quality assurance (QA) tests of the positional and dwell time accuracy are essential to ensure that the accuracy of the remote afterloader is not compromised prior to patient treatment. Our centre has developed an automated, video-based QA system for HDR brachytherapy that is dramatically superior to existing diode or film QA solutions in terms of cost, objectivity, positional accuracy, with additional functionalities such as being able to determine source dwell time and transit time of the source. In our system, a video is taken of the brachytherapy source as it is sent out through a position check ruler, with the source visible through a clear window. Using a proprietary image analysis algorithm, the source position is determined with respect to time as it moves to different positions along the check ruler. The total material cost of the video-based system was under $20, consisting of a commercial webcam and adjustable stand. The accuracy of the position measurement is ±0.2 mm, and the time resolution is 30 msec. Additionally, our system is capable of robustly verifying the source transit time and velocity (a test required by the AAPM and CPQR recommendations), which is currently difficult to perform accurately.

  20. Factors Associated With Chest Wall Toxicity After Accelerated Partial Breast Irradiation Using High-Dose-Rate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: The purpose of this analysis was to evaluate dose-volume relationships associated with a higher probability for developing chest wall toxicity (pain) after accelerated partial breast irradiation (APBI) by using both single-lumen and multilumen brachytherapy. Methods and Materials: Rib dose data were available for 89 patients treated with APBI and were correlated with the development of chest wall/rib pain at any point after treatment. Ribs were contoured on computed tomography planning scans, and rib dose-volume histograms (DVH) along with histograms for other structures were constructed. Rib DVH data for all patients were sampled at all volumes ≥0.008 cubic centimeter (cc) (for maximum dose related to pain) and at volumes of 0.5, 1, 2, and 3 cc for analysis. Rib pain was evaluated at each follow-up visit. Patient responses were marked as yes or no. No attempt was made to grade responses. Eighty-nine responses were available for this analysis. Results: Nineteen patients (21.3%) complained of transient chest wall/rib pain at any point in follow-up. Analysis showed a direct correlation between total dose received and volume of rib irradiated with the probability of developing rib/chest wall pain at any point after follow-up. The median maximum dose at volumes ≥0.008 cc of rib in patients who experienced chest wall pain was 132% of the prescribed dose versus 95% of the prescribed dose in those patients who did not experience pain (p = 0.0035). Conclusions: Although the incidence of chest wall/rib pain is quite low with APBI brachytherapy, attempts should be made to keep the volume of rib irradiated at a minimum and the maximum dose received by the chest wall as low as reasonably achievable.

  1. Radioablation of liver malignancies with interstitial high-dose-rate brachytherapy. Complications and risk factors

    Energy Technology Data Exchange (ETDEWEB)

    Mohnike, Konrad; Wolf, Steffen; Damm, Robert; Seidensticker, Max; Seidensticker, Ricarda; Fischbach, Frank; Pech, Maciej; Ricke, Jens [Otto-von-Guericke-Universitaet, Klinik fuer Radiologie und Nuklearmedizin, Universitaetsklinikum Magdeburg A.oe.R., Magdeburg (Germany); Peters, Nils; Hass, Peter; Gademann, Guenther [Otto-von-Guericke-Universitaet, Klinik fuer Strahlentherapie, Universitaetsklinikum Magdeburg A.oe.R., Magdeburg (Germany)

    2016-05-15

    To evaluate complications and identify risk factors for adverse events in patients undergoing high-dose-rate interstitial brachytherapy (iBT). Data from 192 patients treated in 343 CT- or MRI-guided interventions from 2006-2009 at our institution were analyzed. In 41 %, the largest tumor treated was ≥ 5 cm, 6 % of the patients had tumors ≥ 10 cm. Prior to iBT, 60 % of the patients had chemotherapy, 22 % liver resection, 19 % thermoablation or transarterial chemoembolization (TACE). Safety was the primary endpoint; survival data were obtained as the secondary endpoints. During follow-up, MRI or CT imaging was performed and clinical and laboratory parameters were obtained. The rate of major complications was below 5 %. Five major bleedings (1.5 %) occurred. The frequency of severe bleeding was significantly higher in patients with advanced liver cirrhosis. One patient developed signs of a nonclassic radiation-induced liver disease. In 3 patients, symptomatic gastrointestinal (GI) ulcers were detected. A dose exposure to the GI wall above 14 Gy/ml was a reliable threshold to predict ulcer formation. A combination of C-reactive protein ≥ 165 mg/l and/or leukocyte count ≥ 12.7 Gpt/l on the second day after the intervention predicted infection (sensitivity 90.0 %; specificity 92.8 %.) Two patients (0.6 %) died within 30 days. Median overall survival after the first liver treatment was 20.1 months for all patients and the local recurrence-free surviving proportion was 89 % after 12 months. Image-guided iBT yields a low rate of major complications and is effective. (orig.) [German] Evaluierung der Komplikationsrate und Identifizierung von Risikofaktoren fuer Komplikationen und Nebenwirkungen bei Patienten mit Lebermalignomen, die mit der hochdosierten interstitiellen Brachytherapie (iBT) behandelt wurden. Von 2006 bis 2009 wurden 192 Patienten in 343 CT- oder MRT-gefuehrten Interventionen behandelt und deren Daten ausgewertet. Der groesste behandelte Tumor war in

  2. Interstitial high-dose-rate brachytherapy boost: The feasibility and cosmetic outcome of a fractionated outpatient delivery scheme

    International Nuclear Information System (INIS)

    Purpose: To evaluate the feasibility, potential toxicity, and cosmetic outcome of fractionated interstitial high dose rate (HDR) brachytherapy boost for the management of patients with breast cancer at increased risk for local recurrence. Methods and Materials: From 1994 to 1996, 18 women with early stage breast cancer underwent conventionally fractionated whole breast radiotherapy (50-50.4 Gy) followed by interstitial HDR brachytherapy boost. All were considered to be at high risk for local failure. Seventeen had pathologically confirmed final surgical margins of less than 2 mm or focally positive. Brachytherapy catheter placement and treatment delivery were conducted on an outpatient basis. Preplanning was used to determine optimal catheter positions to enhance dose homogeneity of dose delivery. The total HDR boost dose was 15 Gy delivered in 6 fractions of 2.5 Gy over 3 days. Local control, survival, late toxicities (LENT-SOMA), and cosmetic outcome were recorded in follow-up. In addition, factors potentially influencing cosmesis were analyzed by logistic regression analysis. Results: The minimum follow-up is 40 months with a median 50 months. Sixteen patients were alive without disease at last follow-up. There have been no in-breast failures observed. One patient died with brain metastases, and another died of unrelated causes without evidence of disease. Grade 1-2 late toxicities included 39% with hyperpigmentation, 56% with detectable fibrosis, 28% with occasional discomfort, and 11% with visible telangiectasias. Grade 3 toxicity was reported in one patient as persistent discomfort. Sixty-seven percent of patients were considered to have experienced good/excellent cosmetic outcomes. Factors with a direct relationship to adverse cosmetic outcome were extent of surgical defect (p = 0.00001), primary excision volume (p = 0.017), and total excision volume (p = 0.015). Conclusions: For high risk patients who may benefit from increased doses, interstitial HDR

  3. Cyclotron production and parameters calculation of 48V Nitinol stent for renal arteries in brachytherapy

    International Nuclear Information System (INIS)

    The Nitinol stent was bombarded in a cyclotron at a flux rate of 4 μA/cm2 to produce 48V via 48Ti (p, n) 48V reaction. In this study dose distribution of 48V radioactive stent was investigated for renal arteries. Version X-2.6 of the MCNP Monte Carlo radiation transport system code was employed to calculate dose distribution around the stent. As 48V is a mixed gamma and beta particle emitter, two separate runs of MCNP for both beta and gamma particles were performed and the total deposited dose was acquired by adding the two mentioned values. In order to verify the simulation, the calculated results have been compared with previous published data for the source. Calculated results show high dose gradient near the stent and the maximum amount of dose deposits at the vessel wall. According to (AAPM) TG-60/149 protocol, the dosimetric parameters, including geometry function, G(ρ,z), radial dose function, g L (ρ), and anisotropy function, F(ρ,z), were also determined. (author)

  4. Evaluation of two intracavitary high-dose-rate brachytherapy devices for irradiating additional and irregularly shaped volumes of breast tissue

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Sharon M., E-mail: sharonlu@ucsd.edu [Department of Radiation Oncology and Center for Advanced Radiotherapy Technologies (CART), University of California, San Diego, La Jolla, CA (United States); Scanderbeg, Daniel J.; Barna, Patrick; Yashar, William; Yashar, Catheryn [Department of Radiation Oncology and Center for Advanced Radiotherapy Technologies (CART), University of California, San Diego, La Jolla, CA (United States)

    2012-04-01

    The SAVI and Contura breast brachytherapy applicators represent 2 recent advancements in brachytherapy technology that have expanded the number of women eligible for accelerated partial breast irradiation in the treatment of early-stage breast cancer. Early clinical experience with these 2 single-entry, multichannel high-dose-rate brachytherapy devices confirms their ease of use and dosimetric versatility. However, current clinical guidelines for SAVI and Contura brachytherapy may result in a smaller or less optimal volume of treated tissue compared with traditional interstitial brachytherapy. This study evaluates the feasibility of using the SAVI and Contura to irradiate larger and irregularly shaped target volumes, approaching what is treatable with the interstitial technique. To investigate whether additional tissue can be treated, 17 patients treated with the SAVI and 3 with the Contura were selected. For each patient, the planning target volume (PTV) was modified to extend 1.1 cm, 1.3 cm, and 1.5 cm beyond the tumor bed cavity. To evaluate dose conformance to an irregularly shaped target volume, 9 patients treated with the SAVI and 3 with the Contura were selected from the original 20 patients. The following asymmetric PTV margin combinations were assessed for each patient: 1.5/0.3, 1.3/0.3, and 1.1/0.3 cm. For all patients, treatment planning was performed, adopting the National Surgical Adjuvant Breast and Bowel Project guidelines, and dosimetric comparisons were made. The 6-1 and 8-1 SAVI devices can theoretically treat a maximal tissue margin of 1.5 cm and an asymmetric PTV with margins ranging from 0.3 to 1.5 cm. The 10-1 SAVI and Contura can treat a maximal margin of 1.3 cm and 1.1 cm, respectively, and asymmetric PTV with margins ranging from 0.3-1.3 cm. Compared with the Contura, the SAVI demonstrated greater dosimetric flexibility. Risk of developing excessive hot spots increased with the size of the SAVI device. Both the SAVI and Contura appear

  5. Assessment of radiation doses to the para-aortic, pelvic, and inguinal lymph nodes delivered by image-guided adaptive brachytherapy in locally advanced cervical cancer

    DEFF Research Database (Denmark)

    Mohamed, Sandy M I; Aagaard, Torben; Fokdal, Lars U; Pedersen, Erik Morre; Lindegaard, Jacob C; Tanderup, Kari

    2015-01-01

    PURPOSE: This study evaluated the dose delivered to lymph nodes (LNs) by brachytherapy (BT) and the effect of BT image-guided optimization on the LN dose. METHODS AND MATERIALS: Twenty-five patients with locally advanced cervical cancer were retrospectively analyzed, 16 patients of them had LN...

  6. Long-term results of curative intraluminal high dose rate brachytherapy for endobronchial carcinoma

    Directory of Open Access Journals (Sweden)

    Kawamura Hidemasa

    2012-07-01

    Full Text Available Abstract Background The treatment strategy of central lung tumors is not established. Intraluminal brachytherapy (ILBT is widely used for palliative treatment of endobronchial tumors, however, it is also a promising option for curative treatment with limited data. This study evaluates the results after ILBT for endobronchial carcinoma. Method Sixteen-endobronchial carcinoma of 13 patients treated with ILBT in curative intent for 2000 to 2008 were retrospectively reviewed. ILBT using high dose rate 192 iridium thin wire system was performed with 5 Gy/fraction at mucosal surface. The patient age ranged from 57 to 82 years old with median 75 years old. The 16 lesions consisted of 13 central endobronchial cancers including 7 roentgenographically occult lung cancers and 3 of tracheal cancers. Of them, 10 lesions were treated with ILBT of median 20 Gy combined with external beam radiation therapy of median 45 Gy and 6 lesions were treated with ILBT alone of median 25 Gy. Results Median follow-up time was 32.5 months. Two-year survival rate and local control rate were 92.3% and 86.2%, respectively. Local recurrences were observed in 2 lesions. Three patients died due to lung cancer (1 patient and intercurrent disease (2 patients. Complications greater than grade 2 were not observed except for one grade 3 dyspnea. Conclusions ILBT combined with or without EBRT might be a curative treatment option in inoperable endobronchial carcinoma patients with tolerable complication.

  7. Quality of Life of Oral Cancer Patients After Low-Dose-Rate Interstitial Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To assess the quality of life (QOL) of oral cancer patients treated with low-dose-rate interstitial brachytherapy (LDR-BT) alone. Methods and Materials: Between June 2005 and July 2006, a total of 56 patients with oral cancer were enrolled in this prospective study. QOL was assessed by means of the core questionnaire and head and neck questionnaire module of the European Organization for Research and Treatment of Cancer (EORTC Quality of Life Questionnaire-Core 30 [QLQ-C30] and QLQ Head and Neck 35 [H and N35]). The questionnaires were distributed to the patients before the start of treatment and 3 months, 6 months, and 12 months after the start of LDR-BT. Results: It was possible to analyze the results for 20 of the initial 56 patients because they did not experience metastasis or recurrence during this study. No functions or symptoms asked about in the QLQ-C30 deteriorated during the first year. The emotional function score steadily and significantly increased. No symptoms in the QLQ-H and N35 significantly deteriorated. The scores for pain, trouble with social eating, and weight loss on the QLQ-H and N35 steadily and significantly decreased. Age, gender, and LDR-BT source had no effect on the change in QOL during the first year, but T-stage significantly affected the change in global health status, tumor site affected the changes in swallowing, sensory problems, sticky saliva, and complications affected the changes in pain, swallowing, and mouth opening. Conclusions: QOL of oral cancer patients treated with LDR-BT is high. However, tumor stage, tumor site, and complications affected the changes in a few functions and symptoms during the first year

  8. High-dose-rate interstitial brachytherapy for gynecologic malignancies. Dosimetric changes during treatment period

    International Nuclear Information System (INIS)

    The purpose of this study was to overcome cranio-caudal needle displacement in pelvic high-dose-rate interstitial brachytherapy (HDRIB), we have been utilizing a fullystretched elastic tape to thrust the template into the perineum. The purpose of the current study was to evaluate dosimetric changes during the treatment period using this thrusting method, and to explore reproducible planning methods based on the results of the dosimetric changes. Twenty-nine patients with gynecologic malignancies were treated with HDRIB at the Cancer Institute Hospital. Pre-treatment and post-treatment computed tomography (CT) scans were acquired and a virtual plan for post-treatment CT was produced by applying the dwell positions/times of the original plan. For the post-treatment plan, D90 for the clinical target volume (CTV) and D2cc for the rectum and bladder were assessed and compared with that for the original plan. Cranio-caudal needle displacement relative to CTV during treatment period was only 0.7±1.9 mm. The mean D90 values for the CTV in the pre- and post-treatment plans were stable (6.8 Gy vs. 6.8 Gy) and the post-treatment/pre-treatment D90 ratio was 1.00±0.08. The post-/pre-treatment D2cc ratio was 1.14±0.22 and the mean D2cc for the rectum increased for the post-treatment plan (5.4 Gy vs. 6.1 Gy), especially when parametrial infiltration was present. The mean D2cc for the bladder was stable (6.3 Gy vs. 6.6 Gy) and the ratio was 1.06±0.20. Our thrusting method achieved a stable D90 for the CTV, in contrast to previous prostate HDRIB reports displaying reductions of 35-40% for D90 during the treatment period. (author)

  9. Radiobiological responses for two cell lines following continuous low dose-rate (CLDR) and pulsed dose rate (PDR) brachytherapy

    International Nuclear Information System (INIS)

    The iso-effective irradiation of continuous low-dose-rate (CLDR) irradiation was compared with that of various schedules of pulsed dose rate (PDR) irradiation for cells of two established human lines, T-47D and NHIK 3025. Complete single-dose response curves were obtained for determination of parameters α and β by fitting of the linear quadratic formula. Sublethal damage repair constants μ and T1/2 were determined by split-dose recovery experiments. On basis of the acquired parameters of each cell type the relative effectiveness of the two regimens of irradiation (CLDR and PDR) was calculated by use of Fowler's radiobiological model for iso-effect irradiation for repeated fractions of dose delivered at medium dose rates. For both cell types the predicted and observed relative effectiveness was compared at low and high iso-effect levels. The results indicate that the effect of PDR irradiation predicted by Fowler's model is equal to that of CLDR irradiation for both small and large doses with T-47D cells. With NHIK 3025 cells PDR irradiation induces a larger effect than predicted by the model for small doses, while it induces the predicted effect for high doses. The underlying cause of this difference is unclear, but cell-cycle parameters, like G2-accumulation is tested and found to be the same for the two cell lines

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

    International Nuclear Information System (INIS)

    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)

  11. Effect of improved TLD dosimetry on the determination of dose rate constants for {sup 125}I and {sup 103}Pd brachytherapy seeds

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M., E-mail: manuel.rodriguez@rmp.uhn.ca [Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada and Princess Margaret Hospital, Toronto, Ontario M5G 2M9 (Canada); Rogers, D. W. O. [Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada)

    2014-11-01

    Purpose: To more accurately account for the relative intrinsic energy dependence and relative absorbed-dose energy dependence of TLDs when used to measure dose rate constants (DRCs) for {sup 125}I and {sup 103}Pd brachytherapy seeds, to thereby establish revised “measured values” for all seeds and compare the revised values with Monte Carlo and consensus values. Methods: The relative absorbed-dose energy dependence, f{sup rel}, for TLDs and the phantom correction, P{sub phant}, are calculated for {sup 125}I and {sup 103}Pd seeds using the EGSnrc BrachyDose and DOSXYZnrc codes. The original energy dependence and phantom corrections applied to DRC measurements are replaced by calculated (f{sup rel}){sup −1} and P{sub phant} values for 24 different seed models. By comparing the modified measured DRCs to the MC values, an appropriate relative intrinsic energy dependence, k{sub bq}{sup rel}, is determined. The new P{sub phant} values and relative absorbed-dose sensitivities, S{sub AD}{sup rel}, calculated as the product of (f{sup rel}){sup −1} and (k{sub bq}{sup rel}){sup −1}, are used to individually revise the measured DRCs for comparison with Monte Carlo calculated values and TG-43U1 or TG-43U1S1 consensus values. Results: In general, f{sup rel} is sensitive to the energy spectra and models of the brachytherapy seeds. Values may vary up to 8.4% among {sup 125}I and {sup 103}Pd seed models and common TLD shapes. P{sub phant} values depend primarily on the isotope used. Deduced (k{sub bq}{sup rel}){sup −1} values are 1.074 ± 0.015 and 1.084 ± 0.026 for {sup 125}I and {sup 103}Pd seeds, respectively. For (1 mm){sup 3} chips, this implies an overall absorbed-dose sensitivity relative to {sup 60}Co or 6 MV calibrations of 1.51 ± 1% and 1.47 ± 2% for {sup 125}I and {sup 103}Pd seeds, respectively, as opposed to the widely used value of 1.41. Values of P{sub phant} calculated here have much lower statistical uncertainties than literature values, but

  12. External beam radiotherapy plus single-fraction high dose rate brachytherapy in the treatment of locally advanced prostate cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the efficacy and toxicity of external beam radiation therapy (EBRT) plus high-dose-rate brachytherapy (HDRB) as a boost in patients (pts) with intermediate or high-risk prostate cancer. Methods and materials: From 2002 to July 2012, 377 pts with a diagnosis of intermediate or high-risk prostate cancer were treated with EBRT plus HDRB. Median patient age was 66 years (range, 41–86). Most patients (347 pts; 92%) were classified as high-risk (stage T2c–T3, or PSA > 20 ng/mL, or GS ⩾ 8), with 30 patients (8%) considered intermediate risk. All patients underwent EBRT at a prescribed dose of 60.0 Gy (range, 45–70 Gy) to the prostate and seminal vesicles. A total of 120 pts (31%) received a dose of 46 Gy (45–50 Gy) to the true pelvis. All pts received a single-fraction 9 Gy (9–15 Gy) HDR boost. Most patients (353; 94%) were prescribed complete androgen deprivation therapy (ADT). Overall survival (OS), cause-specific survival (CSS), and biochemical relapse-free survival (BRFS) rates were calculated. In the case of BRFS, patients with <26 months of follow-up (n = 106) were excluded to minimize the impact of ADT. Results: The median follow-up for the entire sample was 50 months (range, 12–126), with 5-year actuarial OS and CSS, respectively, of 88% (95% confidence interval [CI]: 84–92) and 98% (95% CI: 97–99). The 5-year BRFS was 91% (95% CI: 87–95) in the 271 pts with ⩾26 months (median, 60 months) of follow-up. Late toxicity included grade 2 and 3 gastrointestinal toxicity in 17 (4.6%) and 6 pts (1.6%), respectively, as well as grades 2 and 3 genitourinary toxicity in 46 (12.2%) and 3 pts (0.8%), respectively. Conclusion: These long-term outcomes confirm that EBRT plus a single-fraction HDRB boost provides good results in treatment-related toxicity and biochemical control. In addition to the excellent clinical results, this fractionation schedule reduces physician workload, treatment-related expenses, patient discomfort and risks

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

    International Nuclear Information System (INIS)

    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

  14. Low-dose rate prostate brachytherapy is well tolerated in patients with a history of inflammatory bowel disease

    International Nuclear Information System (INIS)

    Purpose: We report on the follow-up of 24 patients with a prior history of inflammatory bowel disease (IBD) treated with brachytherapy for early-stage prostate cancer. Methods and Materials: Twenty-four patients with a history of inflammatory bowel disease (17 with ulcerative colitis (UC), 7 with Crohn's disease [CD]) underwent prostate brachytherapy between 1992 and 2004. Fifteen patients were treated with I-125 implantation and 6 patients were treated with Pd-103 alone or in combination with 45 Gy external beam radiation. Charts were reviewed for all patients, and all living patients were contacted by phone. National Cancer Institute common toxicity scores for proctitis were assigned to all patients. Actuarial risk of late toxicity was calculated by the Kaplan-Meier method. Statistical analysis was performed using SPSS software. Follow-up ranged from 3 to 126 months (median, 48.5 months; mean, 56.8 months). Results: None of the patients experienced Grade 3 or 4 rectal toxicity. Four patients experienced Grade 2 late rectal toxicity. The 5-year actuarial freedom from developing late Grade 2 rectal toxicity was 81%. At a median follow-up of 48.5 months, 23 patients were alive and had no evidence of disease with a median prostate-specific antigen for the sample of 0.1 ng/mL (range, <0.05-0.88 ng/mL). One patient died of other causes unrelated to his prostate cancer. Conclusions: Prostate brachytherapy is well tolerated in patients with a history of controlled IBD. Therefore, brachytherapy should be considered a viable therapeutic option in this patient population

  15. Modulation of toxicity following external beam irradiation preceded by high-dose rate brachytherapy in inoperable oesophageal cancer

    International Nuclear Information System (INIS)

    To induce fast relief of dysphagia in inoperable oesephageal cancer, we applied high-dose rate (HDR) intraluminal irradiation followed by external irradiation (EBRT) in a phase II study. 15 patients (group A: n = 15; 10 men, 5 women; median age 66 years) were treated with 10 Gy HDR brachytherapy plus 40 Gy EBRT (15 fractions of 2.67 Gy). Severe side-effects were encountered in 60% of patients: 3 late ulceration, 2 pending fistula and 2 patients with fatal haemorrhage after an interval of 6 months. Overall response was excellent: 9 complete remissions (60%) and 6 partial responses (40%). Because of the high toxicity rate, in a subsequent study (group B: n = 30; 23 mean, 7 women; median age 66 years) the EBRT scheme was changed using smaller fractions (2.0 Gy) to reach the same total dose of 40 Gy. The complication rate (17%) was significantly reduced, while the overall response remained excellent (83%): 17 complete and 8 partial responses. The impressive change in complication rate of HDR brachytherapy and EBRT stresses the impact of the fraction per dose and illustrates the small therapeutic margins. (author)

  16. Monte Carlo calculation of dose to water of a 106Ru COB-type ophthalmic plaque

    International Nuclear Information System (INIS)

    The concave eye applicators with 106Ru/106Rh or 90Sr/90Y beta-ray sources are worldwide used in brachytherapy for treating intraocular tumors. It raises the need to know the exact dose delivered by beta radiation to tumors but measurement of the dose to water (or tissue) is very difficult due to short range of electrons. The Monte Carlo technique provides a powerful tool for calculation of the dose and dose distributions which helps to predict and determine the doses from different shapes of various types of eye applicators more accurately. The Monte Carlo code MCNPX has been used to calculate dose distributions from a COB-type 106Ru/106Rh ophthalmic applicator manufactured by Eckert and Ziegler BEBIG GmbH. This type of a concave eye applicator has a cut-out whose purpose is to protect the eye nerve which makes the dose distribution more complicated. Several calculations have been performed including depth dose along the applicator central axis and various dose distributions. The depth dose along the applicator central axis and the dose distribution on a spherical surface 1 mm above the plaque inner surface have been compared with measurement data provided by the manufacturer. For distances from 0.5 to 4 mm above the surface, the agreement was within 2.5% and from 5 mm the difference increased from 6% up to 25% at 10 mm whereas the uncertainty on manufacturer data is 20% (2s). It is assumed that the difference is caused by nonuniformly distributed radioactivity over the applicator radioactive layer

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  19. Brachytherapy: Physical and clinical aspects

    International Nuclear Information System (INIS)

    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

  20. BrachyView: Proof-of-principle of a novel in-body gamma camera for low dose-rate prostate brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Petasecca, M.; Loo, K. J.; Safavi-Naeini, M.; Han, Z.; Metcalfe, P. E.; Lerch, M. L. F.; Qi, Y.; Rosenfeld, A. B. [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); Meikle, S. [Brain and Mind Research Institute, University of Sydney, NSW 2006, Australia and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); Pospisil, S.; Jakubek, J. [Institute of Experimental and Applied Physics, Czech Technical University of Prague, Prague (Czech Republic); Bucci, J. A. [St George Cancer Care Centre, St George Hospital, Kogarah, NSW 2217 (Australia); Zaider, M. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States)

    2013-04-15

    Purpose: The conformity of the achieved dose distribution to the treatment plan strongly correlates with the accuracy of seed implantation in a prostate brachytherapy treatment procedure. Incorrect seed placement leads to both short and long term complications, including urethral and rectal toxicity. The authors present BrachyView, a novel concept of a fast intraoperative treatment planning system, to provide real-time seed placement information based on in-body gamma camera data. BrachyView combines the high spatial resolution of a pixellated silicon detector (Medipix2) with the volumetric information acquired by a transrectal ultrasound (TRUS). The two systems will be embedded in the same probe so as to provide anatomically correct seed positions for intraoperative planning and postimplant dosimetry. Dosimetric calculations are based on the TG-43 method using the real position of the seeds. The purpose of this paper is to demonstrate the feasibility of BrachyView using the Medipix2 pixel detector and a pinhole collimator to reconstruct the real-time 3D position of low dose-rate brachytherapy seeds in a phantom. Methods: BrachyView incorporates three Medipix2 detectors coupled to a multipinhole collimator. Three-dimensionally triangulated seed positions from multiple planar images are used to determine the seed placement in a PMMA prostate phantom in real time. MATLAB codes were used to test the reconstruction method and to optimize the device geometry. Results: The results presented in this paper show a 3D position reconstruction accuracy of the seed in the range of 0.5-3 mm for a 10-60 mm seed-to-detector distance interval (Z direction), respectively. The BrachyView system also demonstrates a spatial resolution of 0.25 mm in the XY plane for sources at 10 mm distance from Medipix2 detector plane, comparable to the theoretical value calculated for an equivalent gamma camera arrangement. The authors successfully demonstrated the capability of BrachyView for real

  1. BrachyView: Proof-of-principle of a novel in-body gamma camera for low dose-rate prostate brachytherapy

    International Nuclear Information System (INIS)

    Purpose: The conformity of the achieved dose distribution to the treatment plan strongly correlates with the accuracy of seed implantation in a prostate brachytherapy treatment procedure. Incorrect seed placement leads to both short and long term complications, including urethral and rectal toxicity. The authors present BrachyView, a novel concept of a fast intraoperative treatment planning system, to provide real-time seed placement information based on in-body gamma camera data. BrachyView combines the high spatial resolution of a pixellated silicon detector (Medipix2) with the volumetric information acquired by a transrectal ultrasound (TRUS). The two systems will be embedded in the same probe so as to provide anatomically correct seed positions for intraoperative planning and postimplant dosimetry. Dosimetric calculations are based on the TG-43 method using the real position of the seeds. The purpose of this paper is to demonstrate the feasibility of BrachyView using the Medipix2 pixel detector and a pinhole collimator to reconstruct the real-time 3D position of low dose-rate brachytherapy seeds in a phantom. Methods: BrachyView incorporates three Medipix2 detectors coupled to a multipinhole collimator. Three-dimensionally triangulated seed positions from multiple planar images are used to determine the seed placement in a PMMA prostate phantom in real time. MATLAB codes were used to test the reconstruction method and to optimize the device geometry. Results: The results presented in this paper show a 3D position reconstruction accuracy of the seed in the range of 0.5–3 mm for a 10–60 mm seed-to-detector distance interval (Z direction), respectively. The BrachyView system also demonstrates a spatial resolution of 0.25 mm in the XY plane for sources at 10 mm distance from Medipix2 detector plane, comparable to the theoretical value calculated for an equivalent gamma camera arrangement. The authors successfully demonstrated the capability of BrachyView for

  2. SU-F-19A-03: Dosimetric Advantages in Critical Structure Dose Sparing by Using a Multichannel Cylinder in High Dose Rate Brachytherapy to Treat Vaginal Cuff Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Syh, J; Syh, J; Patel, B; Zhang, J; Wu, H; Rosen, L [Willis-Knighton Cancer Center, Shreveport, LA (United States)

    2014-06-15

    Purpose: The multichannel cylindrical vaginal applicator is a variation of traditional single channel cylindrical vaginal applicator. The multichannel applicator has additional peripheral channels that provide more flexibility in the planning process. The dosimetric advantage is to reduce dose to adjacent organ at risk (OAR) such as bladder and rectum while maintaining target coverage with the dose optimization from additional channels. Methods: Vaginal HDR brachytherapy plans are all CT based. CT images were acquired in 2 mm thickness to keep integrity of cylinder contouring. The CTV of 5mm Rind with prescribed treatment length was reconstructed from 5mm expansion of inserted cylinder. The goal was 95% of CTV covered by 95% of prescribed dose in both single channel planning (SCP)and multichannel planning (MCP) before proceeding any further optimization for dose reduction to critical structures with emphasis on D2cc and V2Gy . Results: This study demonstrated noticeable dose reduction to OAR was apparent in multichannel plans. The D2cc of the rectum and bladder were showing the reduced dose for multichannel versus single channel. The V2Gy of the rectum was 93.72% and 83.79% (p=0.007) for single channel and multichannel respectively (Figure 1 and Table 1). To assure adequate coverage to target while reducing the dose to the OAR without any compromise is the main goal in using multichannel vaginal applicator in HDR brachytherapy. Conclusion: Multichannel plans were optimized using anatomical based inverse optimization algorithm of inverse planning simulation annealing. The optimization solution of the algorithm was to improve the clinical target volume dose coverage while reducing the dose to critical organs such as bladder, rectum and bowels. The comparison between SCP and MCP demonstrated MCP is superior to SCP where the dwell positions were based on geometric array only. It concluded that MCP is preferable and is able to provide certain features superior to SCP.

  3. Verification of dosimetry planning in brachytherapy in format Dicom and EUD calculation of Risk in bodies

    International Nuclear Information System (INIS)

    This work Describes a program that automates the verification of the schedules in brachytherapy (configuration and dosimetric treatment parameters) for sources of Ir-192 (mHDR v2) and Co-60 (Co0.A86) from the plan exported in DICOM format data. (Author)

  4. High-Dose-Rate Brachytherapy for Non-Small-Cell Lung Carcinoma: A Retrospective Study of 226 Patients

    International Nuclear Information System (INIS)

    Purpose: To evaluate the efficacy and toxicity of high-dose-rate (HDR) brachytherapy in patients with inoperable endobronchial carcinoma. Methods and Materials: We retrospectively reviewed the records (April 1991-May 2004) of patients with non-small-cell carcinoma, with no extrabronchial spread on computed tomography scans, who underwent HDR brachytherapy because of contraindications to surgery and external beam radiation therapy. Kaplan-Meier survival curves were compared by the log-rank test. Prognostic factors were analyzed by multivariate analysis. Results: 226 patients (223 men, 3 women, mean age: 62.2 years (range, 40-84)) were included. Of those, 217 (97%) had squamous cell carcinoma (Tis/T1/T2/Tx: 60/153/9/4). Dose was prescribed at 1 cm from the radius (24-35 Gy in 4-6 fractions). Mean follow-up was 30.4 months (range, 9-116). Complete endoscopic response rate was 93.6% at 3 months. One hundred twenty-eight patients (56%) died of intercurrent disease (n = 45), local failure (n = 36), metastasis (n = 10), local failure and metastasis (n = 11), complications (n = 13), and other causes (n = 12). The 2-year and 5-year survival rates were, respectively, 57% and 29% (overall) (median, 28.6 months), 81% and 56% (cancer-specific), and 68% and 50% (local disease-free). Acute toxicity included pneumothorax (1.5%) and mucosal inflammation (10%). Late complications were hemoptysis (6.6% with 5% of fatalities), bronchitis (19.5%), and necrosis (3.5%). In multivariate analysis, a distal tumor location and the use of two catheters were associated with improved local disease-free survival (p = 0.003 and p = 0.007, respectively) and a distal tumor location with improved overall survival (p = 0.0001). Conclusions: This large retrospective study confirms that HDR brachytherapy is an efficient and safe treatment in patients with inoperable endobronchial carcinoma.

  5. The biochemical recurrence-free rate in patients who underwent prostate low-dose-rate brachytherapy, using two different definitions

    International Nuclear Information System (INIS)

    To assess the biochemical recurrence (BCR)-free rate in patients who underwent prostate low-dose-rate brachytherapy (LDR-brachytherapy), using two different definitions (Phoenix definition and PSA ≥ 0.2 ng/mL). Two hundreds and three patients who were clinically diagnosed with localized prostate cancer (cT1c-2cN0M0) and underwent LDR-brachytherapy between July 2004 and September 2008 were enrolled. The median follow-up period was 72 months. We evaluated the BCR-free rate using the Phoenix definition and the PSA cut-off value of 0.2 ng/mL, as in the definition for radical prostatectomy. To evaluate an independent variable that can predict BCR, Cox’s proportional hazard regression analysis was carried out. The BCR-free rate in patients using the Phoenix definition was acceptable (5-year: 92.8%). The 5- year BCR-free rate using the strict definition (PSA ≥ 0.2 ng/mL) was 74.1%. Cox’s proportional hazard regression analysis showed that a higher biological effective dose (BED) of ≥180 Gy2 was the only independent variable that could predict BCR (HR: 0.570, 95% C.I.: 0.327-0.994, p = 0.048). Patients with a higher BED (≥180 Gy2) had a significantly higher BCR-free rate than those with a lower BED (<180 Gy2) (5-year BCR-free rate: 80.5% vs. 67.4%). A higher BED ≥180 Gy2 promises a favorable BCR-free rate, even if the strict definition is adopted

  6. Evaluation of linear array MOSFET detectors for in vivo dosimetry to measure rectal dose in DHR brachytherapy

    International Nuclear Information System (INIS)

    Full text: The study aimed to assess the suitability of linear array metal oxide semiconductor field effect transistor detectors (MOSFETs) as in vivo dosimeters to measure rectal dose in high dose rate brachytherapy treatments. The MOSFET arrays were calibrated with an Ir192 source and phantom measurements were performed to check agreement with the treatment planning system. The angular dependence, linearity and constancy of the detectors were evaluated. For in vivo measurements two sites were investigated, transperineal needle implants for prostate cancer and Fletcher suites for cervical cancer. The MOSFETs were inserted into the patients' rectum in theatre inside a modified flatus tube. The patients were then CT scanned for treatment planning. Measured rectal doses during treatment were compared with point dose measurements predicted by the TPS. The MOSFETs were found to require individual calibration factors. The calibration was found to drift by approximately 1% ±0.8 per 500 mV accumulated and varies with distance from source due to energy dependence. In vivo results for prostate patients found only 33% of measured doses agreed with the TPS within ±1O%. For cervix cases 42% of measured doses agreed with the TPS within ± 10%, however of those not agreeing variations of up to 70% were observed. One of the most limiting factors in this study was found to be the inability to prevent the MOSFET moving internally between the time of CT and treatment. Due to the many uncertainties associated with MOSFETs including calibration drift, angular dependence and the inability to know their exact position at the time of treatment, we consider them to be unsuitable for in vivo dosimetry in rectum for HDR brachytherapy. (author)

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

    International Nuclear Information System (INIS)

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of