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Prague, Czech Republic

Pala M.,Charles University | Odrazka K.,Charles University | Holeckova P.,Charles University | Vitek P.,Charles University | And 3 more authors.
Journal of B.U.ON. | Year: 2012

Purpose: The objective of this study was to evaluate the feasibility, toxicity and efficacy of definitive radiochemotherapy with weekly cisplatin in head and neck cancer in a single institutional setting. Methods: Previously untreated patients with stage II-IV head and neck cancer were included. Radiotherapy consisted of 70 Gy/7 weeks/35 fractions. All patients received concurrent cisplatin 40 mg/m2 weekly. Results: Between 2/2002 and 8/2009, 148 consecutive patients (WHO ≤ 2, male to female ratio 6/1, median age 56 years) were treated. The mean follow-up was 40 months. Tumors of the oropharynx were the most frequent (46%) and stage IV predominated (80%). Eighty-nine percent of the patients had received the full radiation treatment as planned. Omission of weekly cisplatin occurred frequently, mainly because of hematological toxicity. Only 64% of the patients completed at least 5 cycles of chemotherapy. Grade 3/4 mucosal toxicity developed in 32% of the patients. The late toxicities were acceptable: 74% of the patients were able to eat solid food during the 1st post-treatment year, 4 patients were not able to swallow at all during the 1st post-treatment year, requiring thus permanent feeding tube. Five cases of osteoradionecrosis of the mandible were reported. Three-year overall survival, locoregional control, time to progression and disease free survival were 34, 60, 52 and 29%, respectively. Conclusion: Definitive radiochemotherapy with weekly cisplatin was toxic, with high rate of morbidity and mortality in this patient population. Five weekly cycles of 40 mg/m2 cisplatin seem to be the dose limit for most patients. Three-year survival was significantly reduced despite the promising high initial response and locoregional control. © 2012 Zerbinis Medical Publications.


Dammer J.,Czech Technical University | Sopko V.,Czech Technical University | Jakubek J.,Czech Technical University | Weyda F.,Academy of Sciences of the Czech Republic | And 2 more authors.
Astroparticle, Particle, Space Physics and Detectors for Physics Applications - Proceedings of the 13th ICATPP Conference | Year: 2012

We describe a newly developed radiographic system equipped with Medipix2 semiconductor pixel detector and a micro-focus FeinFocus X-ray tube tabletop. The detector is used as an imager that counts individual photons of ionizing radiation, emitted by the X-ray tube. The digital pixel detectors of the Medipix family represent a highly efficient type of imaging devices with high spatial resolution better than 1μm, and unlimited dynamic range allowing single particle of radiation and to determine their energies. The setup is particularly suitable for radiographic imaging of small biological samples, including in vivo observations with various contrast agents (iodine and lanthanum nitrate). Along with the description of the apparatus we provide examples of application of iodine and lanthanum nitrate contrast agents as tracers in various insects as model organisms. The iodine contrast agent increases the absorption of X-rays and this leads to better resolution of internal structures of biological organisms, and especially the various cavities, pores, etc. Micro-radiographic imaging helps to detect organisms living in a not visible environment, visualize internal biological processes and also to resolve the details of their body (morphology). Tiny live insects are an ideal object for our studies.


Sopko V.,University Hospital Na Bulovce | Sopko V.,Czech Technical University | Sopko B.,Czech Technical University | Sopko B.,J.E. Purkyne University in Usti nad Labem | And 4 more authors.
Journal of Instrumentation | Year: 2013

Characterization of radiation defects is still ongoing and finds greater application in the increasing radiation doses on semiconductor detectors in experiments. Studying the changes of silicon PIN diode for high doses of radiation is the fundamental motivation for our measurements. In this article we describe the behavior of the PIN diode and development of the disorder caused by neutrons from a 252Cf and doses up to 8 Gy. The calibration curve for PIN diode shows the effect of disorders as the changes of the voltampere characteristics depending on the dose of neutron irradiation. The measured values for defects are in good agreement with created energy traps.© 2013 IOP Publishing Ltd and Sissa Medialab srl.


Dammer J.,Czech Technical University | Dammer J.,University Hospital Na Bulovce | Weyda F.,Academy of Sciences of the Czech Republic | Weyda F.,University of South Bohemia | And 5 more authors.
Journal of Instrumentation | Year: 2011

Microradiography is an imaging technique using X-rays in the study of internal structures of objects. This rapid and convenient imaging tool is based on differential X-ray attenuation by various tissues and structures within the biological sample. The non-absorbed radiation is detected with a suitable detector and creates a radiographic image. In order to detect the differential properties of X-rays passing through structures sample with different compositions, an adequate high-quality imaging detector is needed. We describe the recently developed radiographic apparatus, equipped with Timepix semiconductor pixel detector. The detector is used as an imager that counts individual photons of ionizing radiation, emitted by an X-ray tube FeinFocus with tungsten, copper or molybdenum anode. Thanks to the wide dynamic range, time over threshold mode - counter is used as Wilkinson type ADC allowing direct energy measurement in each pixel of Timepix detector and its high spatial resolution better than 1μm, the setup is particularly suitable for radiographic imaging of small biological samples. We are able to visualize some internal biological processes and also to resolve the details of insects (morphology) using different anodes. These anodes generate different energy spectra. These spectra depend on the anode material. The resulting radiographic images varies according to the selected anode. Tiny live insects are an ideal object for our studies. © 2011 IOP Publishing Ltd and SISSA.


Dammer J.,University Hospital Na Bulovce | Dammer J.,Czech Technical University | Dammer J.,Charles University | Weyda F.,University of South Bohemia | And 5 more authors.
Journal of Instrumentation | Year: 2013

Radiography serves as a powerful non-destructive technique for studying inner structure of biological samples and materials. In the last years X-ray imaging has taken advantage of the developments in instrumentation such as table-top micro-focus X-ray tubes and quantum counting pixel detectors. The imaging setups used for our measurements allow for the observation of tiny samples including fossils in amber. The main goal of the study was to apply microradiography as representative of non-destructive and non-invasive methods for imaging fossils in amber. Those fossils are generally not easy to visualize, especially their internal structures. We investigated a combination of sources and detectors: (a) an X-ray unit for mammography with tungsten anode, emissive spot of 100 μm and an amorphous selenium imager; (b) a micro-focus X-ray tube with tungsten anode, emissive spot of 5 μm and a flat panel imager; (c) a nano-focus X-ray tube with tungsten anode, with gauge of emissive spot of 1 μm and as imager the pixel semiconductor detector Medipix2. The study of fossils in amber can be for example not well visible because of the presence of organic detritus from various sources. The amber preserves various ancient biological objects which are fully or partly saturated with amber resin. These samples attenuate X-rays similarly, but the use of pixel detectors enables capturing these differences, without permanent destruction of the samples (cracking, slicing, etc.). Microradiographic studies are completed by the observation of amber fossils in scanning and transmission electron microscopes. © 2013 IOP Publishing Ltd and Sissa Medialab srl.

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