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radiation dosimetry

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https://www.readbyqxmd.com/read/29165619/comparison-of-response-of-passive-dosimetry-systems-in-scanning-proton-radiotherapy-a-study-using-paediatric-anthropomorphic-phantoms
#1
Ž Kneževic, I Ambrozova, C Domingo, M De Saint-Hubert, M Majer, I Martínez-Rovira, S Miljanic, N Mojzeszek, P Porwol, O Ploc, M Romero-Expósito, L Stolarczyk, S Trinkl, R M Harrison, P Olko
Proton beam therapy has advantages in comparison to conventional photon radiotherapy due to the physical properties of proton beams (e.g. sharp distal fall off, adjustable range and modulation). In proton therapy, there is the possibility of sparing healthy tissue close to the target volume. This is especially important when tumours are located next to critical organs and while treating cancer in paediatric patients. On the other hand, the interactions of protons with matter result in the production of secondary radiation, mostly neutrons and gamma radiation, which deposit their energy at a distance from the target...
November 18, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29164632/characterization-of-nanodot-optically-stimulated-luminescence-detectors-and-high-sensitivity-mcp-n-thermoluminescent-detectors-in-the-40-300-kvp-energy-range
#2
Yannick Poirier, Svetlana Kuznetsova, Jose Eduardo Villarreal-Barajas
PURPOSE: To investigate empirically the energy dependence of the detector response of two in-vivo luminescence detectors, LiF:Mg,Cu,P (MCP-N) high-sensitivity TLDs and Al2 O3 :C OSLDs, in the 40-300-kVp energy range in the context of in-vivo surface dose measurement. As these detectors become more prevalent in clinical and pre-clinical in-vivo measurements, knowledge of the variation of the empirical dependence of the measured response of these detectors across a wide spectrum of beam qualities is important...
November 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/29159764/establishing-iaea-trs-457-diagnostic-x-ray-beam-qualities-at-the-australian-primary-standard-dosimetry-laboratory
#3
Kam L Lee, Duncan Butler, Tracy Bailey
This paper reports the process and findings in establishing the diagnostic beam qualities for the calibration of diagnostic dose meters in the Australian primary standard dosimetry laboratory at the Australian Radiation Protection and Nuclear Safety Agency, ARPANSA. A novel iterative method to achieve the RQR beam quality requirements described by IEC 61267 is presented. The correction factors for the primary standard free-air chamber and their uncertainties are reported. The calibration procedure with detailed uncertainty budget of a typical diagnostic ionisation chamber (model PTW 34060) is reported...
November 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/29158832/clinical-translation-and-first-in-human-use-of-44-sc-sc-psma-617-for-pet-imaging-of-metastasized-castrate-resistant-prostate-cancer
#4
Elisabeth Eppard, Ana de la Fuente, Martina Benešová, Ambreen Khawar, Ralph A Bundschuh, Florian C Gärtner, Barbara Kreppel, Klaus Kopka, Markus Essler, Frank Rösch
BACKGROUND: Various trivalent radiometals are well suited for labeling of DOTA-conjugated variants of Glu-ureido-based prostate-specific membrane antigen (PSMA) inhibitors. The DOTA-conjugate PSMA-617 has proven high potential in PSMA radioligand therapy (PSMA-RLT) of prostate cancer as well as PET imaging when labeled with lutetium-177 and gallium-68 respectively. Considering the relatively short physical half-life of gallium-68 this positron emitter precludes prolonged acquisition periods, as required for pre-therapeutic dosimetry or intraoperative applications...
2017: Theranostics
https://www.readbyqxmd.com/read/29158362/cd38-bispecific-antibody-pretargeted-radioimmunotherapy-for-multiple-myeloma-and-other-b-cell-malignancies
#5
Damian J Green, Shyril O'Steen, Yukang Lin, Melilssa L Comstock, Aimee L Kenoyer, Donald K Hamlin, D Scott Wilbur, Darrell R Fisher, Margaret Nartea, Mark D Hylarides, Ajay K Gopal, Theodore A Gooley, Johnnie J Orozco, Brian G Till, Kelly D Orcutt, K Dane Wittrup, Oliver W Press
Pretargeted radioimmunotherapy (PRIT) has demonstrated remarkable efficacy targeting tumor antigens, but immunogenicity and endogenous biotin blocking may limit clinical translation. We describe a new PRIT approach for the treatment of Multiple Myeloma (MM) and other B cell malignancies, for which we developed an anti-CD38 bispecific fusion protein that eliminates endogenous biotin interference and immunogenic elements. In murine xenograft models of MM and non-Hodgkin lymphoma (NHL), the CD38 bispecific construct demonstrated excellent blood clearance and tumor targeting...
November 20, 2017: Blood
https://www.readbyqxmd.com/read/29158037/quantitative-imaging-dosimetry-and-metrology-where-do-national-metrology-institutes-fit-in
#6
A J Fenwick, J L Wevrett, K M Ferreira, A M Denis-Bacelar, A P Robinson
In External Beam Radiotherapy, National Metrology Institutes (NMIs) play a critical role in the delivery of accurate absorbed doses to patients undergoing treatment. In contrast for nuclear medicine the role of the NMI is less clear and although significant work has been done in order to establish links for activity measurement, the calculation of administered absorbed doses is not traceable in the same manner as EBRT. Over recent decades the use of novel radiolabelled pharmaceuticals has increased dramatically...
November 11, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29155416/eye-lens-dose-monitoring-in-the-uk-nuclear-industry-using-active-personal-dosemeters
#7
Andrew Forrest McWhan, Wioletta Dobrzynska
The reduction of the dose limit for eye lens from 150 to 20 mSv year-1 must be implemented by EU member states by February 2018. Consequently, there is a requirement for all employers engaged with work with ionising radiation to have appropriate monitoring arrangements in place by this date to demonstrate that they can meet this new limit for all workers. Eye lens dose is conventionally monitored by specific dosemeters worn near the eye. However, it is usually impractical for these dosemeters to be worn at all times in the workplace which can lead to problems accounting for any periods of work when an eye lens dosemeter has not been worn...
November 20, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29154259/evaluation-of-coefficients-to-derive-organ-and-effective-doses-from-cone-beam-ct-cbct-scans-a-monte-carlo-study
#8
Abdullah Abuhaimed, Colin J Martin
Regular imaging is used throughout image guided radiation therapy (IGRT) to improve treatment delivery. In order for treatment procedures to be optimized, the doses delivered by imaging exposures should be taken into account. CT dosimetry methods based on the CT dose index (CTDI), measured with a 100 mm long pencil ionization chamber (CTDI<sub>100</sub>) in standard phantoms, are not designed for the cone beam CT (CBCT) imaging systems used in radiotherapy, therefore a modified version has been proposed for CBCT by the International Electrotechnical Commission (CTDI<sub>IEC</sub>)...
November 20, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29152840/on-the-use-of-bolus-for-pacemaker-dose-measurement-and-reduction-in-radiation-therapy
#9
Huagang Yan, Fanqing Guo, Dengsong Zhu, Stefan Stryker, Sharron Trumpore, Kenneth Roberts, Susan Higgins, Ravinder Nath, Zhe Chen, Wu Liu
Special attention is required in planning and administering radiation therapy to patients with cardiac implantable electronic devices (CIEDs), such as pacemaker and defibrillator. The range of dose to CIEDs that can induce malfunction is large among CIEDs. Clinically significant defects have been reported at dose as low as 0.15 Gy. Therefore, accurate estimation of dose to CIED and dose reduction are both important even if the dose is expected to be less than the often-used 2-Gy limit. We investigated the use of bolus in in vivo dosimetry for CIEDs...
November 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29152838/commissioning-of-the-world-s-first-compact-pencil-beam-scanning-proton-therapy-system
#10
Rajesh Pidikiti, Bijal C Patel, Matthew R Maynard, Joseph P Dugas, Joseph Syh, Narayan Sahoo, Hsinshun Terry Wu, Lane R Rosen
This paper summarizes clinical commissioning of the world's first commercial, clinically utilized installation of a compact, image-guided, pencil-beam scanning, intensity-modulated proton therapy system, the IBA Proteus(®) ONE, at the Willis-Knighton Cancer Center (WKCC) in Shreveport, LA. The Proteus(®) ONE is a single-room, compact-gantry system employing a cyclotron-generated proton beam with image guidance via cone-beam CT as well as stereoscopic orthogonal and oblique planar kV imaging. Coupling 220° of gantry rotation with a 6D robotic couch capable of in plane patient rotations of over 180° degrees allows for 360° of treatment access...
November 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29151472/-fricke-gel-dosimeters
#11
Takuya Maeyama
Fricke gel dosimeters are based on the aqueous ferrous sulfate solution that has been used as a reliable chemical dosimeter for more than 90 years. The amount of radiation-induced oxidation of ferrous ions to ferric ions could be evaluated three-dimensionally via optical computed tomography (OCT) or magnetic resonance imaging (MRI). Three-dimensional dosimetry is expected to be a useful tool, in particular, for the verification of complex radiation dose planning in advanced radiation cancer therapy. Compared with other 3D gel dosimeters, there are several problems such as retention of dose distribution or dose sensitivity; however, they can easily be prepared in a chemistry laboratory...
2017: Japanese Journal of Medical Physics
https://www.readbyqxmd.com/read/29151461/-optical-computed-tomography-for-polymer-gel-dosimetry
#12
Hiraku Kawamura, Takaoki Takanashi, Yoshikazu Shimada, Yuichi Sato, Shinji Abe, Satoshi Hara
This article describes an optical computed tomography (OCT) for polymer gel dosimetry, focusing on two systems recently constructed by us. The first OCT system, which is categorized as a first-generation system, comprised a single He-Ne laser, photodiode, and mechanical stages for moving and turning gel dosimeter. Projection data per angle are acquired from turned gel dosimeter. In this system, the reconstructed image is obtained using filtered back-projection (FBP) method from projection data. The second OCT system is a 2D-OCT scanner that utilizes a light panel and a camera detector...
2017: Japanese Journal of Medical Physics
https://www.readbyqxmd.com/read/29149320/organic-scintillator-for-real-time-neutron-dosimetry
#13
Kyle A Beyer, Angela Di Fulvio, Liliana Stolarczyk, Wiktor Parol, Natalia Mojzeszek, Renata Kopéc, Shaun D Clarke, Sara A Pozzi
We developed a radiation detector based on an organic scintillator for spectrometry and dosimetry of out-of-field secondary neutrons from clinical proton beams. The detector consists of an EJ-299-34 crystalline organic scintillator, coupled by fiber optic cable to a silicon photomultiplier (SiPM). Proof of concept measurements were taken with 137Cs and 252Cf, and corresponding simulations were performed in MCNPX-PoliMi. Despite its small size, the detector is able to discriminate between neutron and gamma-rays via pulse shape discrimination...
November 15, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29148432/a-singular-value-decomposition-linear-programming-svdlp-optimization-technique-for-circular-cone-based-robotic-radiotherapy
#14
Bin Liang, Yongbao Li, Wei Ran, Bin Guo, Xuang Xu, Bo Liu, Jiafeng Li, Qiuwen Wu, Fugen Zhou
With robot-controlled linac positioning, the robotic radiotherapy system such as CyberKnife significantly increases the freedom in radiation beam placement, but also imposes more challenges on treatment plan optimization. The resampling mechanism in vendor supplied treatment planning system (MultiPlan) could not fully explore the increased beam direction search space. Besides, a sparse treatment plan (using fewer beams) is desired to improve the treatment efficiency. This study proposes a singular value decomposition linear programming (SVDLP) optimization technique for circular collimator based robotic radiotherapy...
November 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29136230/high-dose-tl-dosimetry-of-reactor-neutrons
#15
Barbara Obryk, Klaudia Malik, Pawel Bilski, Andrzej Igielski, Jan Dankowski, Arkadiusz Kurowski, Rafal Prokopowicz, Krzysztof Pytel
Radiation dose was measured with set of TL dosimeters during checkout of neutron radiation hardness of the ORTEC preamplifier type 142A in the experiment at the MARIA nuclear reactor at the National Centre for Nuclear Research (NCBJ), Otwock-Świerk, Poland. Different types of LiF-based TL detectors have been used for measurements in order to evaluate neutron and non-neutron components of the radiation field in the reactor channel during exposure and to check their relevancy for dose measurements in the reactor environment...
November 10, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29131343/extracting-wair-from-the-electron-beam-measurements-of-domen-and-lamperti
#16
Frédéric Tessier, Claudiu Dorin Cojocaru, Carl Kenneth Ross
PURPOSE: The average energy expended by an energetic electron to create an ion pair in dry air, Wair, is a key quantity in radiation dosimetry. Although Wair is well established for electron energies up to about 3 MeV there is limited data for higher energies. The measurements by Domen and Lamperti [Med. Phys. 3, 294{301 (1976)] using electron beams in the energy range from 15 to 50 MeV can, in principle, be used to deduce values for Wair, if the electron stopping power of graphite and air are known...
November 13, 2017: Medical Physics
https://www.readbyqxmd.com/read/29129050/metal-free-cycloaddition-chemistry-driven-pretargeted-radioimmunotherapy-using-%C3%AE-particle-radiation
#17
Manan Shah, Xiuli Zhang, Raffaella Rossin, Marc S Robillard, Darrell Fisher, Tyler Bueltmann, Freek J M Hoeben, Thomas Quinn
The pretargeted radioimmunotherapy approach (PRIT) decouples the administration of tumor targeting monoclonal antibodies (mAb) from that of the radiolabeled ligand. This multi-step strategy allows delivery of high doses of radiation to tumor cells while minimizing non-specific normal tissue irradiation. In this study, we evaluated the potential of pretargeted α-particle radioimmunotherapy based on inverse electron demand Diels-Alder reaction (IEDAA) between trans-cyclooctene (TCO) and tetrazine (Tz). Two tetrazine based chelators, DOTA-Tz and TCMC-Tz, were synthesized and compared for their radiolabeling efficiency with 212Pb, radiochemical stability and in-vivo pharmacokinetics...
November 12, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/29128690/transcriptome-based-biological-dosimetry-of-gamma-radiation-in-arabidopsis-using-dna-damage-response-genes
#18
Tae Ho Ryu, Jin Kyu Kim, Jeong-Il Kim, Jin-Hong Kim
Plants are used as representative reference biota for the biological assessment of environmental risks such as ionizing radiation due to their immobility. This study proposed a faster, more economical, and more effective method than conventional cytogenetic methods for the biological dosimetry of ionizing radiation in plants (phytodosimetry). We compared various dose-response curves for the radiation-induced DNA damage response (DDR) in Arabidopsis thaliana after relatively "low-dose" gamma irradiation (3, 6, 12, 24, and 48 Gy) below tens of Gy using comet (or single-cell gel electrophoresis), gamma-H2AX, and transcriptomic assays of seven DDR genes (AGO2, BRCA1, GRG, PARP1, RAD17, RAD51, and RPA1E) using quantitative real time PCR...
November 9, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29125984/ultraviolet-germicidal-efficacy-as-a-function-of-pulsed-radiation-parameters-studied-by-spore-film-dosimetry
#19
Stefan Bauer, Hans Holtschmidt, Günter Ott
Disinfection by pulsed ultraviolet (UV) radiation is a commonly used method, e.g. in industry or medicine and can be carried out either with lasers or broadband UV radiation sources. Detrimental effects to biological materials depending on parameters such as pulse duration τ or pulse repetition frequency fp are well-understood for pulsed coherent UV radiation, however, relatively little is known for its incoherent variant. Therefore, within this work, it is the first time that disinfection rates of pulsed and continuous (cw) incoherent UV radiation studied by means of spore film dosimetry are presented, compared with each other, and in a second step further investigated regarding two pulse parameters...
October 28, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/29125832/minibeam-radiotherapy-with-small-animal-irradiators-in-vitro-and-in-vivo-feasibility-studies
#20
Soha Bazyar, Christina R Inscoe, E Timothy O'Brian, Otto Zhou, Yueh Z Lee
Minibeam radiation therapy (MBRT) delivers an ultrahigh dose of x-ray (⩾100 Gy) in 200-1000 µm beams (peaks), separated by wider non-irradiated regions (valleys) usually as a single temporal fraction. Preclinical studies performed at synchrotron facilities revealed that MBRT is able to ablate tumors while maintaining normal tissue integrity. The main purpose of the present study was to develop an efficient and accessible method to perform MBRT using a conventional x-ray irradiator. We then tested this new method both in vitro and in vivo...
November 10, 2017: Physics in Medicine and Biology
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