UK PubMed Central (United Kingdom)

The reference medium for brachytherapy dose measurements is water. Accuracy of dose measurements of brachytherapy sources is critically dependent on precise measurement of the source–detector...Full Text Available

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Aim: Treatment of carcinoma of the uterine cervix by remote afterloading brachytherapy has been accompanied with new isotopes having dose rates different from the classical low-dose rate (LDR) radium source. The dose rate conversion factor from LDR to high-dose rate (HDR) found to be around 0.54 in most studies. As regards medium-dose rate (MDR) brachytherapie, the published data are very few and the experience is still short. In this study the experience of Osaka University Hospital with micro-HDR-Selectron and Selectron-MDR, as a preliminary report of the clinical trial, is presented. Results: The 3-year survival and loco-regional control rates for both modalities were nearly equivalent (62% and 67% for HDR and 68% and 74% for MDR)(totally 45 patients). The cumulative rectal and bladder complication rates were the same in both groups (29% at 3 years), with only 1 patient ...

International Nuclear Information System (INIS)

Brachytherapy refers to short distance treatment of cancer with radiation from small, encapsulated radionuclide sources. This type of treatment is given by placing sources directly into or near the volume to be treated. The dose is then delivered continuously, either over a short period of time (temporary implants) or over the lifetime of the source to a complete decay (permanent implants). This technique is extensively used in the treatments of gynecological, breast, prostate, head and neck, and other soft tissue cancers. The clinical outcomes of this treatment depend on accurate dosimetry and dose delivery. The patient is generally considered to be water equivalent. So the treatment planning system software generally is based on measured or calculated dose distributions in homogenous water medium. In real situation, the treatment volume is not homogenous water medium, but it is a heterogeneous medium consisting of bone, soft tissue, lung, air etc. For better ...

Energy Technology Data Exchange (ETDEWEB)

Cross sections of proton-induced nuclear reactions on highly enriched {sup 192}Os were measured up to 66 MeV by using the stacked-foil irradiation technique. Excitation functions are presented for the reactions {sup 192}Os(p,n){sup 192}Ir, {sup 192}Os(p,3n){sup 190}Ir, {sup 192}Os(p,4n){sup 189}Ir, {sup 192}Os(p,5n){sup 188}Ir, {sup 192}Os(p,6n){sup 187}Ir and {sup 192}Os(p,7n){sup 186}Ir. No earlier experimental cross-section data could be found in the literature except for the {sup 192}Os(p,n){sup 192}Ir process. Our new experimental results are compared with theoretical predictions by means of the theoretical model code ALICE/ASH. Integral thick-target yield calculations were also performed for the {sup 192}Os(p,n){sup 192}Ir and {sup 192}Os(p,3n){sup 190}Ir reactions to evaluate the {sup 190}Ir contamination level, as a function of energy, in the case of ...

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The energy level schemes of /sup 192/Os and /sup 192/Pt have been established on the basis of ..gamma..-..gamma.. coincidence studies using a dual parameter data collection system. Ge(Li) detectors were employed to study the gamma spectra produced in the E.C. and ..beta../sup -/ decays of /sup 192/Ir to /sup 192/Os and /sup 192/Pt, respectively. Thirteen new transitions and three new levels at 1146.95, 1237.35 and 1913.76 keV are suggested. Relative intensities from singles measurements, branching ratios, ..cap alpha..(K) and log ft values were calculated and multipolarities, spins and parities deduced. Comparisons are made with predictions of the Interacting Boson Model calculated on the basis of an O(6) to SU(3) transition.

Science.gov (United States)

Hot dry rock (HDR) contains insufficient permeability and fluid for natural hydrothermal development, but water pumped in a circulation loop through a HDR reservoir (hydraulically fractured between two drill holes) is being tested and evaluated. The formation of such in situ heat transfer systems, and subsequent testing of the man-made geothermal reservoirs in the Jemez volcanic field, New Mexico have already indicated the technical feasibility of the hot dry rock (HDR) geothermal concept. Documented production history and heat-extraction data obtained during the period from 1978 to 1980 have confirmed heat transfer, low water loss, and predictable thermal drawdown models for the HDR systems. During a nine month test of closed-loop heat extraction operations, 15 x 10/sup 6/ kWh of thermal energy were produced. The effective heat-transfer area and volume of the reservoir increased due to secondary ...

CERN Document Server

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.

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The detection limit of Instrumental Neutron Activation Analysis (INAA), about a few microgram per kg, is not sufficient to determine iridium concentrations in most geological samples. Use of the coincidence counting of the 316 and 468 keV gamma-rays emitted during the decay of {sup 192}Ir, improved the sensitivity (0.01 microgram per kg). The high iridium content of the clay layers from the Cretaceous-Tertiary transition (KTB) has been considered as an evidence of the extra-terrestrial origin of the KTB mass extinction. However some results indicate that a significant part of the iridium content in sediments has a volcanic origin. Radiochemical Neutron Activation Analysis (RNAA) in some KTB samples and in basic and ultra-basic rocks show that, unlike in volcanic products, no PGE (platinoids) fractionation appears in KTB samples. The nearby chondritic PGE pattern supports an extra-terrestrial origin for the KTB iridium anomaly. 2 figs., 2 tabs., ...

Energy Technology Data Exchange (ETDEWEB)

Brachytherapy consists of sealed radioactive source implantation. The diversity in the nature of radioelements, in their energy and activity requires strict implantation and utilization rules. These rules include radioactive source physical parameters check, after-loading machine and treatment planning system quality assurance and safe and reproducible dosimetric systems. Patient and medical workers information guarantee radioprotection and prevention of accidental exposures. (authors)

Science.gov (United States)

The NCRP Wound Model, which describes the retention of selected radionuclides at the site of a contaminated wound and their uptake into the transfer compartment, has been combined with the ICRP element-specific systemic models for those radionuclides to derive dose coefficients for intakes via contaminated wounds. These coefficients can be used to generate derived regulatory guidance (i.e., the activity in a wound that would result in an effective dose of 20 or 50 mSv, or in some cases, a organ-equivalent dose of 500 mSv) and clinical decision guidance (i.e., activity levels that would indicate the need for consideration of medical intervention to remove activity from the wound site, administration of decorporation therapy or both). Data are provided for 38 radionuclides commonly encountered in various activities such as nuclear weapons, fuel fabrication or recycling, waste disposal, medicine, research, and nuclear power. These include 3H, 14C, 32P, 35S, 59Fe, 57,58,60Co, 85,89,90Sr, ...

British Library Electronic Table of Contents (United Kingdom)

Prostate cancer can be successfully treated using dynamic adaptive external beam radiation techniques along with interstitial brachytherapy to deliver curative therapies with low urinary, rectal and erectile function morbidity. Through the use of sophisticated, state-of-the art radiographic imaging for staging and treatment planning, a precise, individual design for treatment is accomplished. Symptom management and patient education are of paramount importance and are integrated throughout the treatment process.

CERN Document Server

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.

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The results of interstitial brachytherapy in 13 patients with malignant brain tumors (malignant glioma 9 cases, metastatic brain tumor 4 cases) were reported. In all patients, Ir-192 thin wires were implanted temporarily in afterloading catheters, which were implanted appropriately by means of MRI or CT guided stereotactic technique. Clinical results on CT scan were as follows: CR (complete response) 1 case, PR (partial response) 6 cases and NC (no change) 6 cases. Even in the NC group, tumor growth was inhibited temporarily. Tumor free intervals were ranged 2-17 months. In early series, the intervals were about 2 months due to incomplete arrangement of radioactive implants. In recent series, prolongation of tumor free interval more than 12 months was achieved due to precise arrangements of implants. MRI guided stereotactic interstitial brachytherapy may provide safe and precise intracranial arrangements of implants, which yield high radiation ...

UK PubMed Central (United Kingdom)

PurposeRTOG protocol 95-17 was a phase I/II trial to evaluate multi-catheter brachytherapy as the sole method of adjuvant breast radiotherapy for stage I/II breast...Full Text Available

International Nuclear Information System (INIS)

The dosimetric characteristics for a new brachytherapy seed source (I-Plant"T"M model 3600) were measured using LiF thermoluminescent dosimeters and appropriate phantom materials in conformance with the methodology and guidance provided by the AAPM Task Group 43. The I-Plant"T"M model 3600 is the successor to the I-Plant"T"M model 3500. The major difference between these sources is that the model 3600 contains a leaded-glass core to provide radio-opacity (while the model 3500 contains a silver core), which does not produce spectral contamination upon neutron activation. The dose rate constant #LAMBDA# for the model 3600 was determined to be 1.00 Gy h"-"1 U"-"1 (with a 6% overall relative standard deviation), compared to 1.01 cGy h"-"1 U"-"1 reported for the model 3500 in previous studies. The remaining dosimetric characteristics also are similar for both sources.

International Nuclear Information System (INIS)

Rectum reference dose points have a direct impact on the morbidity seen in gynecological intracavitaty radiotherapy. The aim of this study is to obtain less morbidity by marking rectum with radio opaque solution. Fourteen patients with gynecological cancer who underwent external radiotherapy received 15 Gray (Gy) intracavitary radiotherapy. During the internal radiotherapy planning, radio opaque solution has been administered into the rectum to observe it on lateral radiogram. Thus rectum reference dose point and five points were marked at sites nearest to the sources. Nucletron Planning system was used for obtaining three-dimensional planning. After therapy patients were followed at every three months. Median follow-up was 18 months. Most frequently observed morbidities were grade 1-2 rectitis and cystitis in six patients. As a result, more accurate rectum dose values and less factors causing dose changing can provide better results for gynecological intracavitary ...

Energy Technology Data Exchange (ETDEWEB)

Objective: To retrospectively evaluate the results of conservative therapy using escorpal iodine-125 (model 6711, Amershan) plaque for brachytherapy of choroidal melanoma. Materials And Methods: We evaluated 49 patients with choroidal melanoma treated at 'Hospital do Cancer', Sao Paulo, Brazil, from March 2001 to January 2003. The following clinical parameters were analyzed and correlated with local control and survival rate: gender, age, lesion dimension, treatment duration, as well as doses in apex and base of the tumors. Results: The maximum diameter and height of the base of the tumors treated were 17 mm and 12 mm, respectively. Doses at those points ranged from 213 to 463 Gy (median: 347 Gy) and 51 to 250 Gy (median: 91 Gy), respectively. The actuarial rates of ocular preservation, disease free survival and ocular preservation in 2-years were 96%, 93.5% and 96.3%, respectively. A tumor height < 6 mm was the only predictive factor for ...

Energy Technology Data Exchange (ETDEWEB)

With regard to a fracture system in the Hijiori hot dry rock artificial reservoir, an attempt was made on an interpretation which integrates different data. Major factors that characterize development and performance of an artificial reservoir are composed of a fracture system in rocks, which acts as circulating water paths, a heat exchange face and a reservoir space. The system relates not only with crack density distribution, but also with cracks activated by water pressure fracturing, cracks generating acoustic emission (AE), and cracks working as major flow paths, all of which are characterized by having respective behaviors and roles. Characteristics are shown on AE cluster distribution, crack distribution, production zone and estimated stress fields. Mutual relationship among these elements was discussed based on the Coulomb`s theory. The most important paths are characterized by distribution of slippery cracks. Directions and appearance frequencies of the slippery cracks affect ...

International Nuclear Information System (INIS)

The effect of measurement geometry on the determination of the activity of solutions containing "1"2"5I for use in brachytherapy applications has been investigated for 5 mL plastic syringes and 2 mL conical glass dose vials as a function of filling mass. New dial settings for the syringes over a filling mass range of 1 to 3 g have been determined to be 497#+-#8 and 469#+-#8 (expanded, k=2, uncertainties) for the NIST Capintec CRC-12 and Capintec CRC-35R, respectively, with any effect due to the filling mass lying within the uncertainty in the activity calibration. A filling mass effect was observed in the dose vials, causing a 10.5% reduction in the chamber response from a 2 g filling mass to 1 g. Dial settings at 2 g were experimentally found to be 143#+-#2 and 135#+-#2 (expanded uncertainties) for the NIST Capintec CRC-12 and Capintec CRC-35R, respectively. The appropriate dial settings for the same vials with a 1 g filling mass were found to be 120#+-#2 and ...

CERN Document Server

Monte Carlo calculations using the codes PENELOPE and GEANT4 have been performed to characterize the dosimetric parameters of the new 20 mm long catheter based $^{32}$P beta source manufactured by Guidant Corporation. The dose distribution along the transverse axis and the two dimensional dose rate table have been calculated. Also, the dose rate at the reference point, the radial dose function and the anisotropy function were evaluated according to the adapted TG-60 formalism for cylindrical sources. PENELOPE and GEANT4 codes were first verified against previous results corresponding to the old 27 mm Guidant $^{32}$P beta source. The dose rate at the reference point for the unsheathed 27 mm source in water was calculated to be $0.215 \\pm 0.001$ cGy s$^{-1}$ mCi$^{-1}$, for PENELOPE, and $0.2312 \\pm 0.0008$ cGy s$^{-1}$ mCi$^{-1}$, for GEANT4. For the unsheathed 20 mm source these values were $0.2908 \\pm 0.0009$ cGy s$^{-1}$ mCi$^{-1}$ and $0.311 \\pm 0.001$ cGy s$^{-1}$ mCi$^{-1}$, ...

Energy Technology Data Exchange (ETDEWEB)

From 1977 through 1984, 293 previously untreated patients with biopsy proven carcinoma of the uterine cervix were treated by whole pelvis irradiation and high intensity 60Co remote afterloading (RAL) intrauterine tandem techniques in Haiti. The treatment results were analyzed retrospectively to evaluate the therapeutic results and prognostic factors of a strict protocol involving 40 Gy to the whole pelvis (2 Gy/day, 5 days/week). In addition, on the 5th day of the 3rd week, the first outpatient 60Co remote afterloading intracavitary insertion, delivering 7.5 Gy to point A with each insertion, repeated 3 times by a week separation for a total of 4 times. The total TDF for external beam plus RAL was 158 and 175 for early and late effects respectively. One hundred-four patients were evaluable after 1 year or more follow-up, with a median of 26.5 months. No evidence of disease (NED) by Stage at 1 year was: Stage I of 100% (3/3), Stage II of 82% (9/11), Stage III of 80% (47/59), and Stage ...