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https://www.readbyqxmd.com/read/29140458/direct-measurements-of-skin-eye-lens-and-thyroid-dose-during-pediatric-brain-ct-examinations
#1
Agapi Ploussi, Ioannis Stathopoulos, Vasileios Syrgiamiotis, Triantafillia Makri, Christiana Hatzigiorgi, Kalliopi Platoni, Eleftheria Carinou, Efstathios P Efstathopoulos
Pediatric brain computed tomography (CT) is identified as the most frequent CT examination in children. The aim of the study is the direct measurement of skin, eye lens and thyroid dose in pediatric patients during brain CT examinations. The study included 35 pediatric patients who underwent brain CT examinations. The patients were categorized in three age groups: Group A (age range: 0.8-1 years), Group B (age range: 2.0-4.9 years) and Group C (age range: 5.5-15.5 years). thermoluminescent dosimeters (TLDs) were placed on the eyes, the frontal region of the head, the mastoid apophysis and the thyroid gland...
November 13, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29136280/transitqa-a-new-method-for-transit-dosimetry-of-tomotherapy-patients
#2
Olivier Pisaturo, Frédéric Miéville, Pierre-Alain Tercier, Abdelkarim Said Allal
PURPOSE: TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with nothing in the beam path from the leaf control sinogram, allowing us to check whether the planned treatment is correctly delivered by the machine. TransitQA allows us to check the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors...
November 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/29136230/high-dose-tl-dosimetry-of-reactor-neutrons
#3
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/29134951/iron-based-radiochromic-systems-for-uv-dosimetry-applications
#4
Hannah Jungeun Lee, Mamdooh Alqathami, Anton Blencowe, Geoffrey S Ibbott
Phototherapy treatment using ultraviolet (UV) A and B light sources has long existed as a treatment option for various skin conditions. Quality control for phototherapy treatment recommended by the British Association of Dermatologists and British Photodermatology Group generally focused on instrumentation-based dosimetry measurements. The purpose of this study was to present an alternative, easily prepared dosimeter system for the measurement of UV dose and as a simple quality assurance technique for phototherapy treatments...
November 14, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29131344/aerrow-a-probe-format-graphite-calorimeter-for-absolute-dosimetry-of-high-energy-photon-beams-in-the-clinical-environment
#5
James Renaud, Arman Sarfehnia, Julien Bancheri, Jan Seuntjens
In this work, the design, operation, initial experimental evaluation, and characterization of a small-scale graphite calorimeter probe - herein referred to as the Aerrow - developed for routine use in the clinical environment, is described. Similar in size and shape to a Farmer type cylindrical ionization chamber, the Aerrow represents the first translation of calorimetry intended for direct use by clinical physicists in the radiotherapy clinic METHODS: Based on a numerically-optimized design obtained in previous work, a functioning Aerrow prototype capable of two independent modes of operation (quasi-adiabatic and isothermal) was constructed in-house...
November 13, 2017: Medical Physics
https://www.readbyqxmd.com/read/29131343/extracting-wair-from-the-electron-beam-measurements-of-domen-and-lamperti
#6
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/29130901/quantification-of-fat-fraction-in-lumbar-vertebrae-correlation-with-age-and-implications-for-bone-marrow-dosimetry-in-molecular-radiotherapy
#7
Maikol Salas-Ramirez, Johannes Tran-Gia, Christian Kesenheimer, Andreas Max Weng, Aleksander Kosmala, Anke Heidemeier, Herbert Koestler, Michael Lassmann
Absorbed dose to active bone marrow is a predictor of hematological toxicity in molecular radiotherapy. Due to the complex composition of bone marrow tissue, the necessity to improve the personalized dosimetry has led to the application of non-conventional imaging methods in nuclear medicine. The aim of this study is to apply magnetic resonance imaging (MRI) for quantification of the fat fraction in lumbar vertebrae and to analyze its implications for bone marrow dosimetry. Methods First, a highly accelerated two-point Dixon MRI sequence for fat-water separation was validated in a 3T system against the magnetic resonance spectroscopy (MRS) gold standard...
November 13, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29129076/comprehensive-molecular-characterization-of-a-cisplatin-specific-monoclonal-antibody
#8
Lena Ruhe, Stefanie Ickert, Ulrike Hochkirch, Johanna Hofmann, Sebastian Beck, Jürgen Thomale, Michael W Linscheid
Despite their immense and rapidly increasing importance as analytical tools or therapeutic drugs, the detailed structural features of particular monoclonal antibodies are widely unknown. Here, an antibody already in use for diagnostic purposes and for molecular dosimetry studies in cancer therapy with very high affinity and specificity for cisplatin-induced DNA modifications was studied extensively. The molecular structure and modifications as well as the antigen specificity were investigated mainly by mass spectrometry...
November 11, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29129050/metal-free-cycloaddition-chemistry-driven-pretargeted-radioimmunotherapy-using-%C3%AE-particle-radiation
#9
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
#10
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
#11
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
#12
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
https://www.readbyqxmd.com/read/29125780/segmentation-of-whole-body-images-into-two-compartments-in-model-for-bone-marrow-dosimetry-increases-the-correlation-with-hematological-response-in-177-lu-dotatate-treatments
#13
Linn Hagmarker, Johanna Svensson, Tobias Rydén, Peter Gjertsson, Peter Bernhardt
BACKGROUND: In (177)Lu-DOTATATE treatments, bone marrow (BM) is one of the most important organs at risk. The authors previously developed an image-based two-compartment method for BM dosimetry, showing a significant correlation between absorbed dose to BM and hematological toxicity in (177)Lu-DOTATATE treatments. In the present study, they aimed to further evaluate this BM dosimetry method by finding optimal settings for dividing the whole body into two compartments; in terms of minimizing the coefficient of variation (CV) for the individual absorbed doses and studying its correlation to the BM response...
November 2017: Cancer Biotherapy & Radiopharmaceuticals
https://www.readbyqxmd.com/read/29125224/normalize-the-response-of-epid-in-pursuit-of-linear-accelerator-dosimetry-standardization
#14
Bin Cai, S Murty Goddu, Sridhar Yaddanapudi, Douglas Caruthers, Jie Wen, Camille Noel, Sasa Mutic, Baozhou Sun
Normalize the response of electronic portal imaging device (EPID) is the first step toward an EPID-based standardization of Linear Accelerator (linac) dosimetry quality assurance. In this study, we described an approach to generate two-dimensional (2D) pixel sensitivity maps (PSM) for EPIDs response normalization utilizing an alternative beam and dark-field (ABDF) image acquisition technique and large overlapping field irradiations. The automated image acquisition was performed by XML-controlled machine operation and the PSM was generated based on a recursive calculation algorithm for Varian linacs equipped with aS1000 and aS1200 imager panels...
November 10, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29124712/safety-and-efficacy-of-phototherapy-in-the-management-of-eczema
#15
Annalisa Patrizi, Beatrice Raone, Giulia Maria Ravaioli
Atopic Dermatitis (AD), a common skin disease, can occur in patients of all age, gender and ethnicity. It is an inflammatory affection, characterized by chronic and highly debilitating behavior. First-line interventions against AD include environmental measures and topical emollients, corticosteroids or calcineurin inhibitors. When these measures are not sufficient, phototherapy represents an efficient second-line option of treatment; it can be administered on its own, or in the most severe cases combined with systemic medicaments such as corticosteroids...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29123014/positron-emission-tomography-using-a-grpr-antagonist-68-ga-rm26-in-healthy-volunteers-and-prostate-cancer-patients
#16
Jingjing Zhang, Gang Niu, Xingrong Fan, Lixin Lang, Guozhu Hou, Libo Chen, Huanwen Wu, Zhaohui Zhu, Fang Li, Xiaoyuan Chen
This study was designed to study the safety, biodistribution, radiation dosimetry of a gastrin-releasing peptide receptor (GRPR) antagonist positron emission tomography (PET) tracer (68)Ga-RM26, to assess its clinical diagnostic value in prostate cancer patients, and to perform a direct comparison between GRPR antagonist (68)Ga-RM26 and agonist (68)Ga-BBN. Methods: Five healthy volunteers were enrolled to validate the safety of (68)Ga-RM26 and calculate dosimetry. A total of 28 patients with prostate cancer (17 newly diagnosed and 11 post therapy) were recruited with written informed consent...
November 9, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/29122512/-salvage-prostate-brachytherapy-a-solution-for-local-failures-after-a-primary-radiation-therapy
#17
J-M Cosset, G Créhange
Salvage brachytherapy after a first prostate radiation therapy is an emerging technique, which has to be considered in the therapeutic armamentarium in the clinically challenging context of patients with isolated local failure from prostate cancer who may still be considered for cure. These occult failures are more and more frequently diagnosed at an early stage, thanks to targeted biopsies and advances in imaging modalities, such as multiparametric MRI and PET-CT. Salvage brachytherapy benefits from the implantation accuracy of brachytherapy procedures using 3D dosimetry and has resulted in more than 50% tumour control rates with long-term...
November 6, 2017: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
https://www.readbyqxmd.com/read/29122421/evaluating-strategies-for-reducing-scattered-radiation-in-fixed-imaging-hybrid-operating-suites
#18
Claire Miller, Daniel Kendrick, Andrew Shevitz, Ann Kim, Henry Baele, David Jordan, Vikram S Kashyap
OBJECTIVE: High-resolution fixed C-arm fluoroscopic systems allow high-quality endovascular imaging but come at a cost of greater scatter radiation generation and increased occupational exposure for surgeons. The purpose of this study was to evaluate the efficacy of two methods in reducing scattered radiation exposure. METHODS: There were 164 endovascular cases analyzed in three phases. In phase 1 (P1), baseline radiation exposure was calculated. In phase 2 (P2), staff used real-time radiation dose monitoring (dosimetry badges [RaySafe; Unfors, Hopkinton, Mass])...
November 6, 2017: Journal of Vascular Surgery
https://www.readbyqxmd.com/read/29117181/pancreatic-uptake-and-radiation-dosimetry-of-6-18f-fluoro-l-dopa-from-pet-imaging-studies-in-infants-with-congenital-hyperinsulinism
#19
Pradeep K Garg, Stephen J Lokitz, Lisa Truong, Burton Putegnat, Courtney Reynolds, Larry Rodriguez, Rachid Nazih, Jonathan Nedrelow, Miguel de la Guardia, John K Uffman, Sudha Garg, Paul S Thornton
METHODS: After injecting 25.6 ± 8.8 MBq (0.7 ± 0.2 mCi) of 18F-Fluoro-L-DOPA intravenously, three static PET scans were acquired at 20, 30, and 40 min post injection in 3-D mode on 10 patients (6 male, 4 female) with congenital hyperinsulinism. Regions of interest (ROIs) were drawn over several organs visible in the reconstructed PET/CT images and time activity curves (TACs) were generated. Residence times were calculated using the TAC data. The radiation absorbed dose for the whole body was calculated by entering the residence times in the OLINDA/EXM 1...
2017: PloS One
https://www.readbyqxmd.com/read/29116057/numerical-assessment-of-low-frequency-dosimetry-from-sampled-magnetic-fields
#20
Fabio Freschi, Luca Giaccone, Vincenzo Cirimele, Aldo Canova
Low-frequency dosimetry is commonly assessed by evaluating the electric field in the human body using the scalar potential finite dif- ference method. This method is effective only when the sources of the magnetic field are completely known and the magnetic vector po- tential can be analytically computed. The aim of the paper is to present a rigorous method to characterize the source term when only the magnetic flux density is available at discrete points, e.g. in case of field measurements. The method is based on the solution of the discrete magnetic curl equation...
November 8, 2017: Physics in Medicine and Biology
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