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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
Michael B Wayson, Wesley E Bolch
Internal radiation dose estimates for diagnostic nuclear medicine procedures are typically calculated for a reference individual. Resultantly, there is uncertainty when determining the organ doses to patients who are not at 50th percentile on either height or weight. This study aims to better personalize internal radiation dose estimates for individual patients by modifying the dose estimates calculated for reference individuals based on easily obtainable morphometric characteristics of the patient. Phantoms of different sitting heights and waist circumferences were constructed based on computational reference phantoms for the newborn, 10-year-old, and adult...
March 16, 2018: Physics in Medicine and Biology
Michael B Wayson, Wesley E Bolch
Various computational tools are currently available that facilitate patient organ dosimetry in diagnostic nuclear medicine, yet they are typically restricted to reporting organ doses to ICRP-defined reference phantoms. The present study, while remaining computational phantom based, provides straightforward tools to adjust reference phantom organ dose for both internal photon and electron sources. A wide variety of monoenergetic specific absorbed fractions (SAFs) were computed using radiation transport simulations for tissue spheres of varying size and separation distance...
March 16, 2018: Physics in Medicine and Biology
Ye Ji Kim, Youn Gon Lee, Dong Won Lee, Jae Hui Kim
Purpose: To evaluate short-term treatment outcomes following selective retina therapy (SRT) with real-time feedback-controlled dosimetry in Korean patients with acute idiopathic central serous chorioretinopathy (CSC). Methods: Sixteen eyes (16 patients) with acute idiopathic CSC (symptom duration < 3 months) were included in this retrospective study. All patients underwent a single session of SRT with real-time feedback-controlled dosimetry. Best-corrected visual acuity (BCVA) and central foveal thickness (CFT) before and 3 months after treatment were examined and compared...
2018: Journal of Ophthalmology
Christopher D Zevitas, John D Spengler, Byron Jones, Eileen McNeely, Brent Coull, Xiaodong Cao, Sin Ming Loo, Anna-Kate Hard, Joseph G Allen
OBJECTIVE: To measure sound levels in the aircraft cabin during different phases of flight. METHODS: Sound level was measured on 200 flights, representing six aircraft groups using continuous monitors. A linear mixed-effects model with random intercept was used to test for significant differences in mean sound level by aircraft model and across each flight phase as well as by flight phase, airplane type, measurement location and proximity to engine noise. RESULTS: Mean sound levels across all flight phases and aircraft groups ranged from 37...
March 15, 2018: Journal of Exposure Science & Environmental Epidemiology
Marilyne Kafrouni, Carole Allimant, Marjolaine Fourcade, Sébastien Vauclin, Julien Delicque, Alina-Diana Ilonca, Boris Guiu, Federico Manna, Nicolas Molinari, Denis Mariano-Goulart, Fayçal Ben Bouallègue
The aim of this study was to quantitatively evaluate the body surface area (BSA) model ability to predict tumor absorbed dose and treatment outcome through retrospective voxel-based dosimetry. Methods: Data from thirty-five hepatocellular carcinoma patients with a total of forty-two resin microsphere radioembolization treatments were included. Injected activity was planned with the BSA model. Voxel dosimetry based on99m Tc-labeled macroaggregated albumin SPECT and90 Y-microsphere PET was retrospectively performed using a dedicated treatment planning system (PLANET® Dose, DOSIsoft SA, Cachan, France)...
March 15, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
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
Wen-Zhao Sun, Dan-Dan Zhang, Ying-Lin Peng, Li Chen, De-Hua Kang, Bin Wang, Xiao-Wu Deng
BACKGROUND: Conventional phantom-based planar dosimetry (2D-PBD) quality assurance (QA) using gamma pass rate (GP (%)) is inadequate to reflect clinically relevant dose error in intensity-modulated radiation therapy (IMRT), owing to a lack of information regarding patient anatomy and volumetric dose distribution. This study aimed to evaluate the dose distribution accuracy of IMRT delivery for nasopharyngeal carcinoma (NPC), which passed the 2D-PBD verification, using a measurement-guided 3D dose reconstruction (3D-MGR) method...
March 15, 2018: Radiation Oncology
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
Raquel M Schears, Zainab Farzal, Zehra Farzal, Anne C Fischer
BACKGROUND: The actual baseline of radiation exposure used in evaluating pediatric trauma is not known and has relied on estimates in the literature that may not reflect clinical reality. Our objectives were to determine the baseline amount of radiation delivered in a pediatric trauma evaluation and correlate radiation exposure with trauma activation status to identify the cohort most at risk. METHODS: We retrospectively evaluated trauma patients (N = 1050) at an independent Level I children's hospital for each level of trauma activation (consults, alerts, stats) from June 2010 to January 2011...
March 14, 2018: International Journal of Emergency Medicine
James R Kerns, David Followill, Jessica Lowenstein, Andrea Molineu, Paola Alvarez, Paige A Taylor, Stephen F Kry
PURPOSE: Reference dosimetry data can provide an independent second check of acquired values when commissioning or validating a treatment planning system (TPS). The Imaging and Radiation Oncology Core at Houston (IROC-Houston) has measured numerous linear accelerators throughout its existence. The results of those measurements are given here, comparing accelerators and the agreement of measurement versus institutional TPS calculations. METHODS: Data from IROC-Houston on-site reviews from 2000 through 2014 were analyzed for all Elekta accelerators, approximately 50...
March 14, 2018: Medical Physics
Keyvan Jabbari, Fakhereh Pashaei, Mohammad R Ay, Alireza Amouheidari, Mohammad B Tavakoli
Background: MapCHECK2 is a two-dimensional diode arrays planar dosimetry verification system. Dosimetric results are evaluated with gamma index. This study aims to provide comprehensive information on the impact of various factors on the gamma index values of MapCHECK2, which is mostly used for IMRT dose verification. Methods: Seven fields were planned for 6 and 18 MV photons. The azimuthal angle is defined as any rotation of collimators or the MapCHECK2 around the central axis, which was varied from 5 to -5°...
January 2018: Journal of Medical Signals and Sensors
Charles E Chambers, Hemantha K Koduri
Real time radiation dose monitoring in the cath lab may provide immediate feedback for potential dose reduction during PCI. Radiation dose monitoring to predict potential tissue injury utilizes equipment measured air Kerma at the interventional reference point (IRP) with then calculated specific tissue peak skin dose. The role of the cath lab Quality Committee is not only to assess individual high dose radiation cases but also to create processes and assess new technologies to assure radiation dose is best utilized in all cases...
March 1, 2018: Catheterization and Cardiovascular Interventions
Yuji Nakaguchi, Takeshi Oono, Masato Maruyama, Yoshinobu Shimohigashi, Yudai Kai, Yuya Nakamura
In this study, we evaluated the basic performance of the three-dimensional dose verification system COMPASS (IBA Dosimetry). This system is capable of reconstructing 3D dose distributions on the patient anatomy based on the fluence measured using a new transmission detector (Dolphin, IBA Dosimetry) during treatment. The stability of the absolute dose and geometric calibrations of the COMPASS system with the Dolphin detector were investigated for fundamental validation. Furthermore, multileaf collimator (MLC) test patterns and a complicated volumetric modulated arc therapy (VMAT) plan were used to evaluate the accuracy of the reconstructed dose distributions determined by the COMPASS...
March 12, 2018: Radiological Physics and Technology
Lucy F Matthews, Ivor W Jones
BACKGROUND: The kidneys are the dose-limiting organ in lutetium-177 DOTATATE therapy. Therefore, it is advisable to perform critical organ dosimetry focussed on renal dose in treated patients. A key uncertainty in such dose estimates is the use of standard phantoms to represent the individual patient. The primary aim of this study was to investigate the accuracy of methods for estimating kidney size, and hence absorbed kidney dose, by comparison with individual measurements from computed tomography (CT) imaging...
March 9, 2018: Nuclear Medicine Communications
Saeed Bagherzadeh, Nasrollah Jabbari, Hamid Reza Khalkhali
PURPOSE: The present study attempts to calculate organ-absorbed and effective doses for cancer patients to estimate the possible cancer induction and cancer mortality risks resulting from 64-slice abdominopelvic computed tomography (CT) simulations for radiotherapy treatment planning (RTTP). MATERIALS AND METHODS: A group of 70 patients, who underwent 64-slice abdominopelvic CT scan for RTTP, voluntarily participated in the present study. To calculate organ and effective doses in a standard phantom of 70 kg, the collected dosimetric parameters were used with the ImPACT CT Patient Dosimetry Calculator...
March 12, 2018: International Journal of Radiation Biology
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
Giuseppe Curcio
In the past 20 years of research regarding effects of mobile phone-derived electromagnetic fields (EMFs) on human cognition, attention has been one of the first and most extensively investigated functions. Different domains investigated covered selective, sustained, and divided attention. Here, the most relevant studies on this topic have been reviewed and discussed. A total of 43 studies are reported and summarized: of these, 31 indicated a total absence of statistically significant difference between real and sham signal, 9 showed a partial improvement of attentional performance (mainly increase in speed of performance and/or improvement of accuracy) as a function of real exposure, while the remaining 3 showed inconsistent results (i...
2018: Frontiers in Public Health
Thomas Brun, Jean-Marc Bachaud, Pierre Graff-Cailleaud, Bernard Malavaud, Daniel Portalez, Christian Popotte, Richard Aziza, Amélie Lusque, Thomas Filleron, Soléakhéna Ken
PURPOSE: To present the feasibility study of optimal dose coverage in ultra-focal brachytherapy (UFB) with multiparametric MRI for low- and intermediate-risk prostate cancer. METHODS AND MATERIALS: UFB provisional dose plans for small target volumes (<7 cc) were calculated on a prostate training phantom to optimize the seeds number and strength. Clinical UFB consisted in a contour-based nonrigid registration (MRI/Ultrasound) to implant a fiducial marker at the location of the tumor focus...
March 7, 2018: Brachytherapy
Yusuf Menda, Mark T Madsen, Thomas M O'Dorisio, John Sunderland, Leonard G Watkins, Joseph S Dillon, Sarah L Mott, Michael King Schultz, Gideon K D Zamba, David L Bushnell, M Sue O'Dorisio
Pre-therapy PET imaging with86 Y-DOTATOC PET is considered the ideal dosimetry protocol for90 Y-DOTATOC therapy; however, its cost, low availability and the need for infusion of amino acids to mimic the therapy administration limit its use in the clinical setting. Objectives: To develop a dosimetric method for90 Y-DOTATOC therapy using90 Y-DOTATOC PET/CT and Bremsstrahlung SPECT/CT imaging and to determine if dosimetry-based administered activities differed significantly from standard administered dosages. Materials and Methods: This is a prospective Phase 2 trial of90 Y-DOTATOC therapy in patients with somatostatin receptor positive tumors...
March 9, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
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