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Grosser O.S.,Otto Von Guericke University of Magdeburg | Nultsch M.,Otto Von Guericke University of Magdeburg | Laatz K.,Otto Von Guericke University of Magdeburg | Ulrich G.,Otto Von Guericke University of Magdeburg | And 8 more authors.
Zeitschrift fur Medizinische Physik | Year: 2011

During the last years angiographic Selective Internal Radiotherapy (SIRT) with 90Y-labelled microspheres has become a common technique for the local-ablative treatment of cancer patients. SIRT is a palliative therapy concept for the treatment of liver malignancies. As a result of 90Y-decay as β --emitter without a concomitant gamma radiation, Bremsstrahlung imaging is needed to validate the distribution achieved by radioembolisation. This article demonstrates the method of imaging through phantom measurement and shows the advantages of post-therapeutic tomography by means of a patient study. Approaches for further optimization of Bremsstrahlung imaging are discussed. © 2011.

Fitschen J.,Stabsstelle Strahlenschutz und Medizinische Physik | Knoop B.O.,Stabsstelle Strahlenschutz und Medizinische Physik | Behrendt R.,Stabsstelle Strahlenschutz und Medizinische Physik | Knapp W.H.,Klinik Fur Nuklearmedizin | Geworski L.,Stabsstelle Strahlenschutz und Medizinische Physik
Zeitschrift fur Medizinische Physik | Year: 2011

The aim of the study was to estimate the external radiation exposure emitted by the patient to his surroundings after discharge. Being in compliance with legal requirements is especially important when doing multiple therapies.To estimate the effective half-life to be used quite realistically, the individual effective half-lives for 41 patients with 52 therapies were calculated. From the resulting histogram the maximum value was determined to be 100. h. Substituting the physical half-life by this maximum effective half-life results in dose estimates, which are lower but still conservative.In addition, the analysis of dose related parameters for patients who underwent multiple therapies demonstrates that the parameters estimated for the first therapy cannot be transferred to the subsequent ones. © 2011.

Geworski L.,Stabsstelle Strahlenschutz und Medizinische Physik | Karwarth C.,Charite - Medical University of Berlin | Fitz E.,Stabsstelle Strahlenschutz und Medizinische Physik | Plotkin M.,Charite - Medical University of Berlin | Knoop B.,Stabsstelle Strahlenschutz und Medizinische Physik
Zeitschrift fur Medizinische Physik | Year: 2010

Today, in most cases PET examinations are performed using PET/CT hybrid systems. While acceptance testing and routine control of the basic modalities PET and CT, respectively, are described by appropriate regulations, corresponding instructions with regard to the interface connecting both are still missing. This interface includes the adjustment of gantries and patient bed to each other as well as the energy scaling of attenuation coefficients from CT energy to 511 keV. Measurements checking the mechanical adjustment (determination of off-set parameters) are performed following manufacturer's recommendation, with a typical frequency twice a year. On a Biograph 16 (Siemens, Inc.), these measurements were systematically extended to a weekly frequency over an observation period of 10 months, supplemented by measurements with additional load to the patient bed (up to 135 kg), and different vertical bed positions. The results show, that for the construction tested additional off-set measurements for routine control extending well beyond manufacturer's recommendation are not necessary. The energy scaling of attenuation coefficients is depending on methodological aspects and software implementation, and therefore is not part of routine control. On the contrary, the development of appropriate methods for acceptance testing to assess and to determine the mechanical adjustment in all its degrees of freedom as well as the accuracy of attenuation corrected emission data is urgently needed. © 2010.

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