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Objective:To evaluate the accuracy of measurement of the output factor of high-energy photon small field (Scp) using commercial semi-diodes and ionization chambers in small fields in accordance with the IAEA-483 report, which has been proposed that all kinds of detectors should be revised for small field Scp measurement in clinical practice.Methods:EGSnrc of Monte Carlo (MC) software was utilized to simulate the treatment head of Varian Novalis Tx linear accelerator, and the profile curve and relative dose value were generated by simulation in DOSXYZnrc based on derived phase space file. Measurement of PDD and Profiles was used to adjust and validate the simulation mode. Detectors including ionization chambers A16, A14 sL, CC01, CC13, PFD and EFD and semi-diodes PFD, EFD and Razor under different radiation field settings (0.5 cm to 10.0 cm) were employed to measure the profile curves and Scp of FWHM equivalent rectangular fields, which were compared with data of Monte-Carlo simulation. The measurement of Scp was revised by data given in the IAEA-483 report. The data with or without correction were compared with the data of MC simulation.Results:A curve deviation o F<2.0% between MC simulation and PFD measurement was accepted. MC simulated Profiles were consistent with PFD, EFD and Razor measurements, when the field was<3.0 cm. Razor response in the out-field region was 2.3% higher than those of MC and PFD, and it increased with the increment of field and was 3.0% at 10.0 cm. The maximum 20.0%-80.0% penumbra width was detected as 3.0 mm for CC13 at 10.0 cm rectangular field. With the decrease of the radiation field, the deviation relative to MC simulation was increased as for Scp mean values of 7 detectors before correction. The standard deviation (SD) of the measured value was increased rapidly when it was close to 1.0 cm, ranging from 0.009-0.014 for the field of 5.0 cm-1.5 cm to 0.030-0.089 for the field of 1.0 cm-0.5 cm. The mean value of SD for the whole measurement before correction was 0.030. The mean SD of Scp measured by the six probes was 0.008, 0.013 at 0.8 cm and 0.021 at 0.6 cm after correction. When the equivalent field was ≥1.0 cm, the corrected Scp and MC simulation deviation was ranged from -3.6% to -0.5%. The error was between -6.9% and -1.3% when the radiation field was<1.0 cm. Conclusion:The SD of Scp measured by different detectors after correction in accordance to the IAEA-483 report is small, which is in good agreement with the data of MC simulation, suggesting that it could be applied in clinical dosimetry.
ABSTRACT
International Commission on Radiological Protection (ICRP), an independent international organization established in 1925, develops, maintains, and elaborates radiological protection standards, legislation, and guidelines. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) provides scientific evidence. World Health Organization (WHO) and International Atomic Energy Agency (IAEA) utilise the ICRP recommendations to implement radiation protection in practice. Finally, radiation protection agencies in each country adopt the policies, and adapt them to each situation. In Korea, Nuclear Safety and Security Commission is the governmental body for nuclear safety regulation and Korea Institute of Nuclear Safety is a public organization for technical support and R&D in nuclear safety and radiation protection.
Subject(s)
Humans , History, 20th Century , International Agencies/organization & administration , Radiation Injuries/etiology , Radiation Protection/history , Radiation, IonizingABSTRACT
The preceding DIN 6800-2 (1997) protocol has been revised by a German task group and its latest version was published in March 2008 as the national standard dosimetry protocol DIN 6800-2 (2008 March). Since then, in Germany the determination of absorbed dose to water for high-energy photon and electron beams has to be performed according to this new German dosimetry protocol. The IAEA Code of Practice TRS 398 (2000) and the AAPM TG-51 are the two main protocols applied internationally. The new German version has widely adapted the methodology and dosimetric data of TRS-398. This paper investigates systematically the DIN 6800-2 protocol and compares it with the procedures and results obtained by using the international protocols. The investigation was performed with 6 MV and 18 MV photon beams as well as with electron beams from 5 MeV to 21 MeV. While only cylindrical chambers were used for photon beams, the measurements of electron beams were performed by using cylindrical and plane-parallel chambers. It was found that the discrepancies in the determination of absorbed dose to water among the three protocols were 0.23% for photon beams and 1.2% for electron beams. The determination of water absorbed dose was also checked by a national audit procedure using TLDs. The comparison between the measurements following the DIN 6800-2 protocol and the TLD audit-procedure confirmed a difference of less than 2%. The advantage of the new German protocol DIN 6800-2 lies in the renouncement on the cross calibration procedure as well as its clear presentation of formulas and parameters. In the past, the different protocols evoluted differently from time to time. Fortunately today, a good convergence has been obtained in concepts and methods.
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En el mes de octubre de 2005 un pequeño grupo de investigadores de diferentes nacionalidades se reunieron en Viena, Austria, bajo los auspicios del Organismo Internacional de Energía Atómica con el objetivo de preparar un documento sencillo y útil para el personal involucrado en la preparación de productos biológicos radiomarcados como péptidos, proteínas y anticuerpos. Este documento debe incluir los aspectos prácticos, metodológicos y éticos relacionados con los productos radiomarcados anteriormente mencionados y debe esclarecer la ruta crítica que se debe seguir en esa área. Ese documento no cubre el uso de oligonucleótidos, células y otros productos antólogos radiomarcados y no ofrece protocolos técnicos sobre metodologías. En el trabajo presento recomendaciones farmacodinámicas y toxicológicas para los estudios preclínicos in vivo que deben seguir estos productos. Esta guía sólo representa mi forma actual de pensar sobre este tema.
In October of 2005 a small group of researchers from different Countries had a meeting at the International Atomic Energy Agency headquarter in Vienna, Austria; the aim was to prepare a tentative user-friendly document for personnel involved in preparation of radiopharmaceuticals based on peptides, proteins and antibodies for human use. This document should cover all practical, methodological and ethical concerns relating to radiolabelled products mentioned above and should clarify the complicated road-map that one has to follow in this area. This document does not cover the use of radiolabelled oligonucleotides, cells and other autologous products and does not provide technical protocols on actual methodologies. Herein, we will like to present you some pharmacodynamic and toxicological recommendations for in vivo preclinical studies. This guidance only represents my own current thinking in this topic.
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Although Gamma Knife irradiates much more radiation in a single session than conventional radiotherapy, there were only a few studies to measure absolute dose of a Gamma Knife. Especially, there is no report of application of International Atomic Energy Agency (IAEA) TRS-398 which requires to use a water phantom in radiation measurement to Gamma Knife. In this article, the authors reported results of the experiments to measure the absorbed dose to water of a Gamma Knife Model C using the IAEA TRS-398 protocol. The absorbed dose to water of a Gamma Knife model C was measured using a water phantom under conditions as close as possible to the IAEA TRS-398 protocol. The obtained results were compared with values measured using the plastic phantom provided by the Gamma Knife manufacturer. Two Capintec PR-05P mini-chambers and a PTW UNIDOS electrometer were used in measurements. The absorbed dose to water of a Gamma Knife model C inside the water phantom was 1.38% larger than that of the plastic phantom. The current protocol provided by the manufacturer has an intrinsic error stems from the fact that a plastic phantom is used instead of a water phantom. In conclusion, it is not possible to fully apply IAEA TRS-398 to measurement of absorbed dose of a Gamma Knife. Instead, it can be a practical choice to build a new protocol for Gamma Knife or to provide a conversion factor from a water phantom to the plastic phantom. The conversion factor can be obtained in one or two standard laboratories.
Subject(s)
Nuclear Energy , Plastics , Radiotherapy , WaterABSTRACT
The International Atomic Energy Agency (IAEA) under its mandate of developing and applying standards of radiation safety has initiated a number of activities in recent years on radiation protection in interventional cardiology. These activities are implemented through four mechanisms, namely training, providing information through the website, research projects and assistance to Member States through Technical Cooperation (TC) projects. Major international initiatives have been taken in the area of training where more than half a dozen regional training courses have been conducted for cardiologists from over 50 countries. Additionally four national training events for over 300 medical and paramedical staff members involved in interventional procedures were held. The training material is freely available on CD from the IAEA. The newly established website provides information on radiation protection issues [1]. Two coordinated research projects have just been completed where peak skin doses to patients undergoing high dose interventional procedures were studied and factors to manage patient doses were identified. The technical cooperation projects involving protection in cardiac interventional procedures have 30 countries as participants.
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The quality factors for cylindrical ionization chambers for kV X-rays were determined by Monte Carlo calculation and measurement. In this study, the X-rays of 60~300 kV beam (ISO-4037) installed in KFDA and specified in energy spectra and beam qualities, and the chambers of PTW N23333 and N30001 were investigated. In calculations, the k(u) and k(Q,Q(0)) in IAEA dosimetry protocols were determined from the air kerma and the cavity dose obtained by theoretical and Monte Carlo calculations. It is shown that the N30001 chamber has a flat response of +/-1.7% in 110~300 kV region, while the response range of two chambers were shown to +/-3~4% in 80~250 kV region. From this work we have discussed dosimetry protocol for the kV X-rays and we have found that the estimation of energy dependency is more important to apply dosimetry protocol for kV X-rays.