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(124)I is a radionuclide used in the diagnosis of tumors. The National Health Agency requires identification and activity measurement of impurities. Using gamma spectrometry with an efficiency calibrated high-purity germanium detector, impurities (125)I and (126)I in an (1)(24)I production sample were identified. Activity ratios of (125)I and (126)I to (124)I were approximately 0.5% and 98%, respectively., (Published by Elsevier Ltd.)

The national traceability chain for (131)I activity measurements performed in nuclear medicine in Cuba is described. At the highest (primary) level, liquid scintillation counting employing the CIEMAT/NIST method is used; at the secondary level, a secondary standard radionuclide calibrator is utilized that allows for a quick and simple transference of the measurement unit to the tertiary level of end-users' instruments. The equivalence of Cuban standards and the assessment of measurement uncertainties at the end-user level are determined through the results of measurement comparisons., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A photon-photon coincidence system was constructed for the standardization of (125)I and (109)Cd in PTKMR-BATAN, Indonesia. Two NaI(Tl) detectors of 76 mm diameter × 6mm thickness with 0.5mm aluminum window were used, which were positioned approximately symmetrically to the source holder. The electronic chain was almost the same as for a 4πβ-γ system. The CANBERRA Multiport II multi channel analyzer was used for energy calibration and a Philips type PM3092 oscilloscope for visualization of the pulses. A polyethylene plastic was used as the source substrate for the (125)I and (109)Cd samples. The activity of a (125)I solution was measured by the photon-photon coincidence and the efficiency extrapolation method (Schrader and Walz, 1987), whereas the activity of a (109)Cd solution was determined by a tracer method using (125)I (Schrader, 2006). The result of the (125)I activity showed good agreement with the result of measurements using a calibrated ionization chamber, and the result of (109)Cd also showed good agreement with the measurements result using a LEGe detector., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Successful treatment for permanent implant brachytherapy is based on accurate measurement of dosimetry parameters for the seed sources. Literature describes the application of various types of phantom to determine the AAPM TG-43 dosimetry parameters for permanent implant seeds. Previously we created a new type of phantom used to measure the dosimetry parameters of a high dose-rate (192)Ir source. In this study, we modified the phantom to suit to a common type of (125)I seed source (Sinko BT-125-1). The dose-rate constant, radial dose function and anisotropy function of this source were measured in detail and compared with the published values of other similar in-design (125)I seed sources. The experimental results exhibit fairly small measurement uncertainties and good self-consistency. The modified phantom is demonstrated on the measurement of dosimetry parameters for the Sinko BT-125-1 (125)I seed, however, it could easily be used for similar measurements of other permanent implantation seed sources.

Unlabelled: The accuracy with which (123)I activity is measured by a dose calibrator depends on the composition and geometry of the source. The present study assessed the variability of current commercial dose calibrators in assaying liquid (123)I samples., Methods: A calibration procedure for (123)I measurement was performed on 177 dose calibrators (11 manufacturers) at 138 sites in North America and Europe. Using the standard (123)I push-button or dial setting, activity in a 5-mL (123)I calibration source in a 10-mL U.S. Pharmacopeia type 1 glass vial (actual activity previously determined using a National Institute of Standards and Technology-traceable standard metrology chamber) was measured. A portion of the source was then transferred to a plastic syringe (10-, 5-, and 3-mL sizes at different sites), and the activity in the syringe was measured. Calibration factors (CFs) for converting the dose calibrator readings to the reference activities were then determined for the vial and the syringes. Data were analyzed for all calibrators combined and based on device manufacturers. Measurements using a copper attenuator (sleeve) were made for a subset of 10 dose calibrators at sites that used these devices in clinical practice., Results: Mean CFs for the different measurements were as follows: 10-mL vial, 1.278; 10-mL syringe, 0.811; 5-mL syringe, 0.815; 3-mL syringe, 0.792. Almost half of the dose calibrators had vial CFs between 1.2 and 1.3 and 10-mL syringe CFs between 0.7 and 0.8, whereas less than 16% of the instruments had uncorrected readings within ±10% of the reference activities. Although there was a wide range of CFs for different calibrators using the copper sleeve, for each unit the CFs for the glass vial and the 10-mL plastic syringe were virtually identical., Conclusion: On most commercial dose calibrators, the standard (123)I settings result in significant errors in activity measurements for sources in glass vials and plastic syringes. The difference in ionization chamber detection caused by the container composition (glass vs. plastic) is a much larger source of measurement variation than source volume or geometry.

Dosimetric characteristics of brachytherapy sources are normally determined in water using a Monte Carlo simulation technique and in water equivalent phantom material using both experimental and Monte Carlo simulation techniques. The consensuses of these results are then calculated for clinical applications by converting experimental data obtained in water equivalent material to water using a conversion factor. These conversion factors are normally determined as a ratio of the Monte Carlo-simulated dose rate constant in liquid water to the dose rate constant in a water-equivalent phantom material. However, it has been noted that conversion factors utilized by some investigators have been derived using incorrect phantom material composition and incorrect cross-sectional data information. The impact of errors associated with the cross-sectional data and chemical composition of the phantom material used in dosimetric evaluation of brachytherapy sources has been investigated in this project. Results of these investigations have shown that the use of Solid Water with 1.7% calcium content, as compared to the 2.3% value stated by the manufacturer, may lead to 5% and 9% differences in conversion factors for 125I and 103Pd, respectively.

The absolute 4pi-betagamma coincidence counting has been used to measure the activity concentrations of 54Mn and 203Hg, and the Sum-Peak method was used for 125I. 54Mn and 125I radionuclides have been part of international key-comparisons coordinated by the Bureau International des Poids et Measures (BIPM) in 2003/2004, while 203Hg is part of the traceability programme of the National Laboratory for Ionizing Radiation Metrology (LNMRI)/Brazil. Three different detectors were used for the Sum-Peak method: 3''x3'' NaI(Tl) and 5''x5'' well NaI(Tl) scintillation detectors and a planar germanium detector. Direct measurements were made of the photon emission probabilities of the 35.5-, 834.8- and 279.2-keV gamma-rays of 125I, 54Mn and 203Hg to give values of (0.0667+/-0.0014), (0.9997+/-0.0055) and (0.8161+/-0.0005), respectively. The half-lives of 203Hg and 54Mn were also determined by means of a 4pigamma ionization chamber (203Hg) and by the reference source method using a HPGe detector (54Mn) to give values of (46.639+/-0.023) days and (312.1+/-0.9) days, respectively.

Radioactive seeds preloaded in sterilized cartridges or needles are commonly obtainable from manufacturers. Under the US regulations for control of radioactive materials, seed users are required to account for all seeds and independently verify their air kerma strength (SK). As a result, the viability of inspection schemes that rely on measurement of aggregate seeds is of interest. In this paper we consider the conditions (if any) under which cartridge inspection can satisfy regulatory requirements and still provide practical benefit (i.e., time savings) against the regular single-seed assay. The standards for comparison are the recommendations of AAPM TG40, AAPM TG56, and ACR's "Standard for the Performance of Manually Loaded Brachytherapy Sources." The practical benefit is judged in comparison to the effort required to apply the 10% assay recommendation of TG40 to seeds in cartridges. Two specific cartridge inspection schemes are considered: (a) measuring the SK of each cartridge in a batch; (b) measuring a single cartridge sampled at random from the batch. Unlike the 10% assay, which is defined (imperfectly, in our view) without reference to the prevalence of in-calibration seeds, the estimation of the relative merits of cartridge inspection methods must necessarily include such information and, as such, is manufacturer specific. In this paper results are provided for Oncura model 6711 125I seeds in shielded and unshielded Mick cartridges. We show that the only practically useful cartridge inspection scheme is the batch scheme applied to unshielded cartridges. The false positive rates associated with the other schemes are such that we expect to open a cartridge (and perform the 10% assay) at least 80% of the time. While anything less than 100% of the time is theoretically an improvement, this neglects the additional effort required to assay the cartridges.

Calibration of a High-Dose-Rate 1000 Plus ionisation chamber and associated electrometer for the determination of reference air kerma rate for 125I brachytherapy seeds has been developed. Traceability was established from ionisation chamber measurements of an Amersham model 6711 125I seed for which a primary standard measurement of reference air kerma rate has been made by the National Institute of Standards and Technology. The status of an Australian secondary standard is to be realised by establishing legal verifying authority from the National Measurement Institute. The calibrated chamber thus provides a measurement from which similar chambers in hospitals may be calibrated. For quality assurance this result was compared with the calibration certificate supplied by the Accredited Dosimetry Calibration Laboratory of the University of Wisconsin, USA.

In March 2004, the recommendations of the American Association of Physicists in Medicine (AAPM) on the interstitial brachytherapy dosimetry using 125I and 103Pd were reported in Medical Physics [TG-43 Update: Rivard et al., 31, 633-674 (2004)]. These recommendations include some minor changes in the dose-calculation formalism and a major update of the dosimetry parameters for eight widely used interstitial brachytherapy sources. A full implementation of these recommendations could result in unintended changes in delivered dose without corresponding revisions in the prescribed dose. Because most published clinical experience with permanent brachytherapy is based upon two widely used source models, the 125I Model 6711 and 103Pd Model 200 sources, in this report we present an analysis of the dosimetric impact of the 2004 TG-43 dosimetry parameters on the history of dose delivery for these two source models. Our analysis indicates that the currently recommended prescribed dose of 125 Gy for Model 200 103Pd implants planned using previously recommended dosimetry parameters [AAPM 103Pd dose prescription: Williamson et al., Med. Phys. 27, 634-642 (2000)] results in a delivered dose of 120 Gy according to dose calculations based on the 2004 TG-43 update. Further, delivered doses prior to October 1997 varied from 113 to 119 Gy for a prescribed dose of 115 Gy compared to 124 Gy estimated by the AAPM 2000 report. For 125I implants using Model 6711 seeds, there are no significant changes (less than 2%). Practicing physicians should take these results into account when selecting the clinically appropriate prescribed dose for 103Pd interstitial implant patients following implementation of the 2004 TG-43 update dose-calculation recommendations. The AAPM recommends that the radiation oncology community review this report and consider whether the currently recommended dose level (125 Gy) needs to be revised.

Iodine-131 patients pose a radiation risk to their family members, carers and colleagues. Doses from thyrotoxicosis and thyroid cancer patients undergoing standard treatments have been well characterised in the literature. However the resulting precautions cannot be easily adapted to circumstances where the patient has an unusual affliction, or an atypical family or occupational environment. In this study, a model for calculating dose from an I-131 patient is derived from first principles. The model is combined with existing results from the literature to determine a distance weighting factor between patients and family members. This technique reduces the uncertainty in the dose calculations by removing the need to guess the unknown patterns of close contact, a problem common to all previous dose calculation techniques. Data is presented for four unusual I-131 treatments; a child thyroid cancer patient, two thyroid cancer dialysis patients and a phaeochromocytoma patient. The model is used to calculate appropriate periods of restricted contact for these patients. The recommendations provide a useful guide for future unusual I-131 treatments.

A new method using the Monte Carlo code PENELOPE for ionization chamber simulation has already been successfully used for calculating calibration factors needed for the measurements of radionuclides with photon emission (2003, Appl. Radiat. Isot., to be published). This work has been continued at (Laboratoire National Henri Becquerel) in order to calculate the calibration factors for radionuclides with short half-lives used in medical services. Activity measurements of 18F, 99mTc,111In and 123I using the calculated calibration factors were obtained with standard uncertainties equal to 0.6% for 18F, 99mTc and 1.5% for 111In and 123I.

Values of dose rate constant (DRC) in compliance with AAPM TG 60 formalism recommended for intravascular brachytherapy (IVBT) were calculated for different point isotropic mono-energetic photon sources in the energy range E = 20-1000 keV using a semi-analytic model. Based on these DRC values, DRC of some existing models of 192Ir and 125I brachytherapy sources were then calculated using (1) bare energy spectra and (2) a single energy parameter which represents mean energy (photon number weighted or air-kerma weighted) for bare and actual sources or the most probable energy of the spectra (energy line with the highest probability of emission) of the investigated sources (192Ir and 125I). Applicability of the semi-analytic approach was examined by also computing the values of DRC of the investigated sources using MCNP Monte Carlo simulation code (Version 3.1) that involved modeling of the sources accurately. A comparison of values of DRC resulting from MCNP calculations with those resulting from the semi-analytic approach showed that for 192Ir sources the agreement was within 0.40% and for 125I sources it was within 2.3%.

The SeedLink brachytherapy system is comprised from an assembly of I-Plant 3500 interstitial brachytherapy seeds and bioresorbable spacers joined together by a 6-mm-long titanium sleeve centered over each seed. This device is designed to maintain specified spacing between seeds during treatment thereby decreasing implant preparation time and reducing radionuclide migration within the prostate and periprostatic region. Reliable clinical treatment and planning applications necessitate accurate dosimetric data for source evaluation, therefore the authors report the results of a Monte Carlo study designed to calculate the AAPM Task Group Report No. 43 dosimetric parameters for the SeedLink brachytherapy source and compare these values against previously published Monte Carlo study results of the I-Plant 3500 brachytherapy seed. For this investigation, a total of 1 x 10(9) source photon histories were processed for each set of in-water and in-air calculations using the MCNP4C2 Monte Carlo radiation transport code (RSICC). Statistically, the radial dose function, g(r), and the dose-rate constant, lambda, were identical to the values calculated previously for the Model 3500 with the dose-rate constant evaluated to be lambda = 1.000+/-0.026 cGyh(-1) U(-1). The titanium sleeve used in SeedLink to bind together Model 3500 seeds and spacers resulted in slightly greater dosimetric anisotropy as exhibited in the anisotropy function, F(r, theta), the anisotropy factor, phi(an) (r), and the anisotropy constant, phi(an), which was calculated to be phi(an) = 0.91 +/- 0.01, or roughly 2% lower than the value calculated previously for the Model 3500. These results indicate that the radiological characteristics of the SeedLink dosimetry system are comparable to those obtained for previously characterized single seeds such as the Implant Sciences Model 3500 I-Plant seed.

In order to obtain information on the accuracy of activity measurements in Brazilian hospitals, several intercomparison exercises have been organized since 1998. The first exercise consisted of two intercomparison runs of 131I and 99mTc and had the participation of 21 hospitals localized in Rio de Janeiro city and surroundings. The second, with 131I (47 hospitals) and 123I (12 hospitals), had the participation of hospitals localized in the whole country. The results were analyzed under the statistical point of view and conformity to the norms of Regulatory Authority. These results have shown that such exercises are necessary to improve the quality of the measurements and to identify those instruments that are producing incorrect values.

This development relates to nuclear engineering, concerns the sources of ionizing radiation of iodine radionuclides and the ways of their manufacture. The iodine radionuclides are used for calibration of radiometers that measure the specific activity of iodine radionuclide in biological specimens, in particular for their use to identify noncancer diseases. The purpose of the paper is to design a routine activity sample for iodine radionuclide in the solid-state source for transfer of an iodine radionuclide activity unit from the reference iodine radionuclide activity unit to an operating meter with a simultaneous decrease in testing errors and an increase, in terms of iodine radionuclide half-life, in the life of the reference sample by stabilizing the activity unit of iodine radionuclide (in terms of its half-life) by eliminating the process of sublimation of iodine radionuclide from the working surface of the source. The objective is achieved by the fact that the radionuclide is replaced on the lower internal build-up part of the container, fixed with the upper internal build-up part, then kept for at least 10-12 hours at least at 18-20 degrees C, packed into a hollow container and sealed with epoxide resin. According to the proposed technical design, reference activity samples of iodine radionuclide in the solid-state radiometric source with a preset activity value have been prepared. The testing error for iodine radionuclide activity is minimal and equal to 1.0-3.0% at a 0.95 confidence.