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Lukas Zeininger, Maggie He, Stephen T Hobson, Timothy M Swager
We report γ-ray dosimeters using carbon nanotubes wrapped with metastable poly(olefin sulfone)s (POSs) that readily depolymerize when exposed to ionizing radiation. New POSs, designed for wrapping single-walled carbon nanotubes (SWCNTs), are synthesized and characterized. The resulting POS-SWCNT composites serve as the active transducer in a novel class of γ-ray dosimeters. In our devices, polymer degradation results in immediate changes in the electronic potential of the POS-SWCNT active layers by decreasing the electron tunneling barriers between individualized tubes and by creating enhanced cofacial π-π electron contacts...
March 20, 2018: ACS Sensors
M Valente, J Vedelago, D Chacón, F Mattea, J Velásquez, P Pérez
International dosimetry protocols are based on determinations of absorbed dose to water. Ideally, the phantom material should be water equivalent; that is, it should have the same absorption and scatter properties as water. This study presents theoretical, experimental and Monte Carlo modeling of water-equivalence of Fricke and polymer (NIPAM, PAGAT and itaconic acid ITABIS) gel dosimeters. Mass and electronic densities along with effective atomic number were calculated by means of theoretical approaches. Samples were scanned by standard computed tomography...
March 8, 2018: Applied Radiation and Isotopes
Kenji Kinashi, Takato Iwata, Hayato Tsuchida, Wataru Sakai, Naoto Tsutsumi
Polystyrene (PS)-based composite microfibers combined with a photochromic spiropyran dye, 1,3,3-trimethylindolino-6'-nitrobenzopyrylospiran (6-nitro BIPS), and a photostimulable phosphor, europium-doped barium fluorochloride (BaFCl:Eu2+ ), were developed for the detection of X-ray exposure doses on the order of approximately 1 Gy. To produce the PS-based composite microfibers, we employed a forcespinning method that embeds a high concentration of the phosphor in the PS in a safe, inexpensive, and simple procedure...
March 19, 2018: ACS Applied Materials & Interfaces
Mel O'Leary, Daria Boscolo, Nicole Breslin, Jeremy M C Brown, Igor P Dolbnya, Chris Emerson, Catarina Figueira, Oliver J L Fox, David Robert Grimes, Vladimir Ivosev, Annette K Kleppe, Aaron McCulloch, Ian Pape, Chris Polin, Nathan Wardlow, Fred J Currell
Absolute measurements of the radiolytic yield of Fe3+ in a ferrous sulphate dosimeter formulation (6 mM Fe2+), with a 20 keV x-ray monoenergetic beam, are reported. Dose-rate suppression of the radiolytic yield was observed at dose rates lower than and different in nature to those previously reported with x-rays. We present evidence that this effect is most likely to be due to recombination of free radicals radiolytically produced from water. The method used to make these measurements is also new and it provides radiolytic yields which are directly traceable to the SI standards system...
March 16, 2018: Scientific Reports
Kurtis H Dekker, Rubin Hazarika, Matheus A Silveira, Kevin J Jordan
Optical cone beam computed tomography (CT) scanning of radiochromic gel dosimeters, using a CCD camera and a low stray light convergent source, provides fast, truly 3D radiation dosimetry with high accuracy. However, a key limiting factor in radiochromic gel dosimetry at large (⩾10 cm diameter) volumes is the initial attenuation of the dosimeters. It is not unusual to observe a 5-10×  difference in signal intensity through the dosimeter center versus through the surrounding medium in pre-irradiation images...
March 16, 2018: Physics in Medicine and Biology
J Vedelago, F Mattea, M Valente
The use and implementation of nanoparticles in medicine has grown exponentially in the last twenty years. Their main applications include drug delivery, theranostics, tissue engineering and magneto function. Dosimetry techniques can take advantage of inorganic nanoparticles properties and their combination with gel dosimetry techniques could be used as a first step for their later inclusion in radio-diagnostics or radiotherapy treatments. The present study presents preliminary results of properly synthesized and purified silver nanoparticles integration with Fricke gel dosimeters...
March 1, 2018: Applied Radiation and Isotopes
James A Crowhurst, Gregory M Scalia, Mark Whitby, Dale Murdoch, Brendan J Robinson, Arianwen Turner, Liesie Johnston, Swaroop Margale, Sarvesh Natani, Andrew Clarke, Darryl J Burstow, Owen C Raffel, Darren L Walters
BACKGROUND: Transesophageal echocardiography operators (TEEOP) provide critical imaging support for percutaneous structural cardiac intervention procedures. They stand close to the patient and the associated scattered radiation. OBJECTIVES: This study sought to investigate TEEOP radiation dose during percutaneous structural cardiac intervention. METHODS: Key personnel (TEEOP, anesthetist, primary operator [OP1], and secondary operator) wore instantly downloadable personal dosimeters during procedures requiring TEE support...
March 20, 2018: Journal of the American College of Cardiology
David L Georgeson, Byron H Christiansen
Idaho National Laboratory transitioned from an external dosimetry system reliant on thermoluminescent dosimeters to one that uses optically stimulated luminescence dosimeters in 2010. This change not only affected the dosimeters worn by personnel, but those found in the nuclear-accident dosimeters used across Idaho National Laboratory. The elimination of on-site use and processing of thermoluminescent dosimeters impacted Idaho National Laboratory's ability to process nuclear-accident dosimeters in a timely manner...
March 14, 2018: Health Physics
Muzafar Khan, Gerd Heilemann, Peter Kuess, Dietmar Georg, Andreas Berg
Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D) , which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates...
March 12, 2018: Physics in Medicine and Biology
Hannu Jarvinen, Jad Farah, Teemu Siiskonen, Olivera Ciraj-Bjelac, Jérémie Dabin, Eleftheria Carinou, Joanna Domienik-Andrzejewska, Dariusz Kluszczynski, Željka Knežević, Renata Kopec, Marija Majer, Francoise Malchair, Anna Negri, Piotr Pankowski, Sandra Sarmento, Annalisa Trianni
PURPOSE: The feasibility of setting-up generic, hospital-independent dose alert levels to initiate vigilance on possible skin injuries in interventional procedures was studied for three high-dose procedures (chemoembolization (TACE) of the liver, neuro-embolization (NE) and percutaneous coronary intervention (PCI)) in 9 European countries. METHODS: Gafchromic® films and thermoluminescent dosimeters (TLD) were used to determine the Maximum Skin Dose (MSD). Correlation of the online dose indicators (fluoroscopy time, kerma- or dose-area product (KAP or DAP) and cumulative air kerma at interventional reference point (Ka,r )) with MSD was evaluated and used to establish the alert levels corresponding to a MSD of 2 Gy and 5 Gy...
February 2018: Physica Medica: PM
Navin Singh, Sunil Dutt Sharma, Nirmal Kumar Painuly, Abhijit Mandal, Lalit Mohan Agarwal, Ashutosh Sinha
Aims: To evaluate the underdosing of the maxillary sinus at its distal end produced by air cavity in the path of the 6 MV photon beam. Materials and Methods: A cubic solid water slab phantom of dimensions 18 cm × 18 cm × 18 cm with 4 cm × 4 cm × 4 cm air cavity 3 cm away from its anterior surface was used in this study. The percentage depth dose (PDD) for 6 MV X-rays along the central axis of the cubical air cavity was measured using thermoluminescent dosimeter-100 chips...
January 2018: Journal of Cancer Research and Therapeutics
Hasan Ali Nedaie, Farideh Pak, Vahid Vaezzadeh, Ehsan Eqlimi, Abas Takavar, Hamid Reza Saligheh Rad, Mohammad Amin Mosleh Shirazi, Mona Mirheydari
Aim: Low signal-to-noise ratio (SNR) images of lung-like (low-density [LD]) gel dosimeters, compared to unit-density (UD) gels, necessitate the use of different quantification methods. Setting and Design: In this study, a new method is introduced based on noise correction and exponential (NCEXP) fitting. The feasibility of NCEXP method for quantifying dose absorption in LD gels is evaluated. Materials and Methods: Sensitivity, dose resolution, detectable dynamic range, and correlation of the calibration curve for both UD and LD gel dosimeters are the parameters, which we analyze to investigate the consequences of new method...
January 2018: Journal of Cancer Research and Therapeutics
Nahideh Gharehaghaji, Habib Alah Dadgar
Purpose: The main purpose of this study was evaluate a polymer-gel-dosimeter (PGD) for three-dimensional verification of dose distributions in the lung that is called lung-equivalent gel (LEG) and then to compare its result with Monte Carlo (MC) method. Materials and Methods: In the present study, to achieve a lung density for PGD, gel is beaten until foam is obtained, and then sodium dodecyl sulfate is added as a surfactant to increase the surface tension of the gel...
January 2018: Journal of Cancer Research and Therapeutics
Evan Maynard, Emily Heath, Michelle Hilts, Andrew Jirasek
This study introduces the first 3D deformable dosimetry system based on x-ray computed tomography (CT) polymer gel dosimetry (PGD) and establishes the setup reproducibility, deformation characteristics and dose response of the system. A N-isopropylacrylamide (NIPAM)-based gel formulation optimized for X-ray CT gel dosimetry was used, with a latex balloon serving as the deformable container and low-density polyethylene and polyvinyl alcohol providing additional oxygen barrier. Deformable gels were irradiated with a 6 MV calibration pattern to determine dosimetric response and a dosimetrically uniform plan to determine the spatial uniformity of the response...
March 8, 2018: Physics in Medicine and Biology
L Fidalgo Domingos, E M San Norberto García, D Gutiérrez Castillo, C Flota Ruiz, I Estévez Fernández, C Vaquero Puerta
BACKGROUND: Endovascular procedures come with a potential risk of radiation hazards both to patients and to the vascular staff. Classically, most endovascular interventions took place in regular operating rooms using a fluoroscopy C-arm unit controlled by a third party. Hybrid operating rooms (HOR) provide an optimal surgical suit with all the qualities of a fixed C-arm device, while allowing the device to be controlled by the surgical team. The latest studies suggest that an operator-controlled system may reduce the radiation dose...
February 28, 2018: Annals of Vascular Surgery
Alfonso Quintero-Quintero, Galo Patiño Camargo, Ángela Soriano Cruz, Juan Diego Palma Copete, Jorge Vilar Palop, Maria Del Carmen Pujades, Nieves Llorca Domaica, Facundo Ballester, Javier Vijande, Cristian Candela-Juan
Fluoroscopy guided interventional procedures provide remarkable benefits to patients. However, the medical staff working near the scattered radiation field may be exposed to high cumulative equivalent doses, thus requiring shielding devices such as lead aprons and thyroid collars. In this situation, it remains an acceptable practice to derive equivalent doses to the eye lenses or other unprotected soft tissues with a dosimeter placed above these protective devices. Nevertheless, the radiation backscattered by the lead shield differs from that generated during dosimeter calibration with a water phantom...
March 2, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
Laurent Faroux, Thierry Blanpain, Pierre Nazeyrollas, Sophie Tassan-Mangina, Virginie Heroguelle, Christophe Tourneux, Florian Baudin, Damien Metz
Exposure of operators to ionising radiation in interventional cardiology has likely diminished, but data confirming the magnitude of the reduction are lacking. The aim of this study was to compare the dose of radiation received by interventional cardiology operators at 11 years interval (2006 vs 2017). The study population comprised all interventional coronary procedures performed by a single operator in one catheterization laboratory (cathlab) of a large university hospital in north-eastern France. Exposure was compared between two periods, namely period 1 (from October 2005 to March 2006) and period 2 (from March 2017 to June 2017)...
February 9, 2018: International Journal of Cardiology
Hiroaki Hasegawa, Jiro Sato, Ikuo Kobayashi
The authors aimed to evaluate the effects of the half-scan mode on image quality and physician exposure to radiation in computed tomography (CT)-guided interventional radiology (IVR) to the right lung using an intermittent CT fluoroscopy technique for measuring phantom surface dose distribution and image noise. For the half-scan mode, settings at 0°, 90°, 180°, and 270° were used as the central axis of the X-ray exposure range on the chest phantom. With the center of the ventral side in the chest phantom defined as 0°, optically stimulated luminescent dosimeters were attached at five positions at 30° intervals on the right side of the phantom surface...
February 27, 2018: Radiological Physics and Technology
Alexandra J Lin, Sarah J Karinja, Jaime L Bernstein, Julia Jin, Yoshiko Toyoda, Andrew J Miller, Pat B Zanzonico, Jason A Spector
INTRODUCTION: Capsular contracture after breast reconstruction is a morbid complication, occurring in 30.0% to 47.5% of patients undergoing postoperative radiotherapy. Although it is well known that radiation increases rate of capsular contracture, there are few well-established animal models that faithfully replicate standard-of-care clinical practice, that is, prosthesis placement at the time of mastectomy followed by delayed radiotherapy. To better recapitulate current clinical practice, we developed a murine model in which the implant sites were irradiated 10 days postoperatively, rather than at time of surgery...
February 23, 2018: Annals of Plastic Surgery
V Pereda-Loth, X Franceries, A S Afonso, A Ayala, B Eche, D Ginibrière, G Gauquelin-Koch, M Bardiès, L Lacoste-Collin, M Courtade-Saïdi
Astronauts are exposed to microgravity and chronic irradiation but experimental conditions combining these two factors are difficult to reproduce on earth. We have created an experimental device able to combine chronic irradiation and altered gravity that may be used for cell cultures or plant models in a ground based facility. Irradiation was provided by thorium nitrate powder, conditioned so as to constitute a sealed source that could be placed in an incubator. Cell plates or plant seedlings could be placed in direct contact with the source or at various distances above it...
February 2018: Life Sciences in Space Research
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