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The stability of the dose rate and radiation quality in high-energy photon and electron reference radiation fields on the PTB’s linear accelerator could be clearly improved by different modifications of the accelerator.

PTB has a linear accelerator of type Philips SL 75/20 at its disposal which generates reference radiation fields of high-energy photon and electron radiation....

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For the first time, two international comparisons are performed in radiation protection dosimetry. Both EUROMET comparisons are organized by PTB. In photon dosimetry, realization of the depth personal dose Hp(10) is compared, and realization of the superficial personal dose Hp(0.07) in the comparison with beta radiation. For both comparisons, new measuring instruments, which have so far...

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Since the beginning of the year, PTB has offered calibrations of well-type ionization chambers and therapy chambers in the Krieger phantom to indicate the characteristic dose rate or the reference air kerma rate.

Before radiation sources are used for the first time on a patient, the reference air kerma rate of the sources used for intracavitary and interstitial brachytherapy must be...

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With the aid of a water-tight pinpoint ionization chamber developed at PTB, a complete 3d-distribution of the water absorbed dose rate has for the first time been measured directly in the water phantom in the near field of 192Ir and 60Co brachytherapy sources.

In addition to 192Ir high-dose rate sources (HDR sources), 60Co HDR brachytherapy sources have later also been used for the...

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A water calorimeter allows the water absorbed dose to be measured by definition. Due to its compact construction (outer dimensions approx. 65 cm × 60 cm × 65 cm [L×W×H]), the newly constructed calorimeter can also be used as transfer calorimeter for therapeutic radiation fields and is ready for on-site operation within approx. 18 h. At PTB, this water calorimeter is used to determine the...

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The secondary standard measuring facility for the absorbed dose to water in high-energy radiation fields on the basis of Alanin/ESR could be improved by a new probes positioning device. At 5 Gy, the relative reproducibility standard deviation now amounts to 0.4%, and at 25 Gy, a deviation of 0.2% is achieved.

The reproducibility standard deviation of the secondary standard measuring...

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As a result of a solar eruption on January 20, the earth was hit by so many high-energy particles that radiation exposure at flight altitudes temporarily increased. The additional radiation exposure at flight altitudes was estimated by PTB and other European partners to be less than 0.2 mSv. This corresponds to approx. 1 % of the annual limiting value permitted for persons occupationally exposed...

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To measure the radiation exposure at flight altitudes by cosmic radiation, PTB has developed a measuring system in a handy suitcase ("flight case"). In the very complex radiation fields of natural cosmic radiation, it furnishes reliable measurements of the existing ambient dose equivalent. The flight case travelled several months on board of an airbus, and a calculation program was...

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The determination of chromosome aberrations is a sensitive, biological procedure to estimate the dose of ionizing radiation which has been received by an individual. For the systematic investigation of specific influence factors on the validity and reliability of the dose estimation of a radiation exposure, blood samples were irradiated, among others, in the intensive, collimated neutron field at...

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The fluence spectrum of the new 60Co reference radiation field was determined by simulation of the photon transport into the irradiation facility using the Monte Carlo simulation program BEAMnrc. The depth dose curve in the water phantom calculated with the aid of this spectrum shows excellent agreement with the depth dose curves determined by experiment.

When the water absorbed dose...

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For comparison purposes, the "Unit of Activity" Working Group has sent a radioactive 109Cd solution to the International Reference System SIR. The emission rate of the conversion electrons was determined with the aid of pressurized proportional counters and a liquid scintillation spectrometer. In addition, the photon emission rate was measured with the aid of calibrated semiconductor...

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Two generally applicable procedures for an improved determination of the fluence spectra of reference photon radiation fields were developed.

Within the scope of quality assurance, the pulse height spectra of reference photon radiation fields used in dosimetry for X-ray diagnostics and radiation therapy are measured at regular intervals with a Ge-spectrometer and a special measuring...

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The Monte Carlo program GESPECOR was extended to calculate corrections for two-, three- and fourfold coincidences between gamma-rays and K X-rays and for escape lines. This allows the coincidence summation corrections to be calculated for the first time for all lines measured in a spectrum.

Spectrometric measurements of gamma-ray emitting radionuclides at a small distance from a...

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For photon dosimetry, a secondary standard was further developed for the ambient dose equivalent H*(10). After optimization, a secondary standard ionization chamber is now for the first time available for the photon energy range from 12 keV to 6.7 MeV. Dissemination of the unit H*(10) is thus also guaranteed in the low-energy range below 25 keV, in which the realization of H*(10) is very...

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At PTB, a new relative measuring procedure for activity determination with the aid of 4π liquid scintillation counting was developed and tested. In the procedure, the detection probability of a radionuclide is traced back to a 3H reference solution which makes the method very resistant to changes of the measuring device. The procedure is also suitable for small activities and shall be further...

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A transportable and compact water calorimeter was used in hospitals and research institutes which use different types of particle beams for cancer therapy: in a collimated neutron beam (Clinical Centre, Essen), in proton beams (HMI in Berlin and iTHEMBA LABS in South Africa) and in a 12C heavy ion therapy beam (GSI in Darmstadt). The water absorbed dose was determined with uncertainties of less...

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To completely describe the neutron emission after tungsten has been bombarded with neutrons, differential elastic and inelastic cross sections were determined with as high an accuracy as possible for neutron energies between 7 MeV and 14 MeV.

As the metal with the highest melting point, tungsten is extremely heat-resistant and can be used as material with a very effective shielding of fast...

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Within the scope of the systematic investigation of high-energy photon fields in the energy range from 4 MeV to 7 MeV, additional neutrons from the 13C(p,n)13N reaction have been investigated in the 4.4 MeV photon field from the 12C(p,p'γ)12C reaction. The neutron fraction in the ambient dose equivalent amounts to 60% of the photon fraction. For calibrations of neutron-sensitive measuring...

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Im Rahmen einer Dissertation wurden Messungen der räumlichen Ionisationsverteilung von schweren Ionen mit gleichem Energieverlust, aber unterschiedlicher Ladung durchgeführt und mit Rechnungen verglichen.

Die unterschiedliche biologische Wirksamkeit von Ionen gleichen spezifischen Energieverlustes, aber verschiedener Kernladung ist die Folge der unterschiedlichen radialen...

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For the NEMUS neutron spectrometer, part of the data acquisition system has been modernized. The old ISA-Port multi-channel analyzer printed circuit boards were replaced by new, independent systems which are linked with the measuring PC via an Internet connection.

NEMUS (Neutron Multisphere Spectrometer) serves as a reference system for the spectrometry and dosimetry of unknown...

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