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Radiation dose measurements

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https://www.readbyqxmd.com/read/27932562/intraoperative-assessment-of-tumor-resection-margins-in-breast-conserving-surgery-using-18f-fdg-cerenkov-luminescence-imaging-a-first-in-human-feasibility-study
#1
Maarten Ruben Grootendorst, Massimiliano Cariati, Sarah Pinder, Ashutosh Kothari, Michael Douek, Tibor Kovacs, Hisham Hamed, Amit Pawa, Fiona Nimmo, Julie Owen, Vernie Ramalingam, Sweta Sethi, Sanjay Mistry, Kunal Vyas, David Tuch, Alan Britten, Mieke Van Hemelrijck, Gary Cook, Chris Sibley-Allen, Sarah Allen, Arnie Purushotham
RATIONALE: In early-stage breast cancer, the primary treatment option for the majority of women is breast-conserving surgery (BCS). There is a clear need for more accurate techniques to assess resection margins intraoperatively, as on average 20% of patients require further surgery to achieve clear margins. Cerenkov luminescence imaging (CLI) combines optical and molecular imaging by detecting light emitted by (18)F-fluorodeoxyglucose ((18)F-FDG). Its high-resolution and small size imaging equipment makes CLI a promising technology for intraoperative margin assessment...
December 8, 2016: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/27930717/a-patient-specific-polylactic-acid-bolus-made-by-a-3d-printer-for-breast-cancer-radiation-therapy
#2
So-Yeon Park, Chang Heon Choi, Jong Min Park, MinSoo Chun, Ji Hye Han, Jung-In Kim
PURPOSE: The aim of this study was to assess the feasibility and advantages of a patient-specific breast bolus made using a 3D printer technique. METHODS: We used the anthropomorphic female phantom with breast attachments, which volumes are 200, 300, 400, 500 and 650 cc. We simulated the treatment for a right breast patient using parallel opposed tangential fields. Treatment plans were used to investigate the effect of unwanted air gaps under bolus on the dose distribution of the whole breast...
2016: PloS One
https://www.readbyqxmd.com/read/27929516/the-feasibility-of-using-microsoft-kinect-v2-sensors-during-radiotherapy-delivery
#3
David M Edmunds, Sophie E Bashforth, Fatemeh Tahavori, Kevin Wells, Ellen M Donovan
Consumer-grade distance sensors, such as the Microsoft Kinect devices (v1 and v2), have been investigated for use as marker-free motion monitoring systems for radiotherapy. The radiotherapy delivery environment is challenging for such sen-sors because of the proximity to electromagnetic interference (EMI) from the pulse forming network which fires the magnetron and electron gun of a linear accelerator (linac) during radiation delivery, as well as the requirement to operate them from the control area. This work investigated whether using Kinect v2 sensors as motion monitors was feasible during radiation delivery...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929511/evaluation-of-dose-area-product-of-common-radiographic-examinations-towards-establishing-a-preliminary-diagnostic-reference-levels-pdrls-in-southwestern-nigeria
#4
Nnamdi N Jibiri, Christopher J Olowookere
In Nigeria, a large number of radiographic examinations are conducted yearly for various diagnostic purposes. However, most examinations carried out do not have records of doses received by the patients, and the employed exposure parameters used are not documented; therefore, adequate radiation dose management is hin-dered. The aim of the present study was to estimate the dose-area product (DAP) of patients examined in Nigeria, and to propose regional reference dose levels for nine common examinations (chest PA, abdomen AP, pelvis AP, lumbar AP, skull AP, leg AP, knee AP, hand AP, and thigh AP) undertaken in Nigeria...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929506/dose-reduction-in-ct-urography-and-vasculature-phantom-studies-using-model-based-iterative-reconstruction
#5
Leland Page, Wei Wei, Vikas Kundra, John Rong
To evaluate the feasibility of radiation dose reduction using model-based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue-equivalent CT dose phantom was scanned using a 64-channel CT scan-ner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index (CTDIvol) of 24 mGy...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929502/epid-based-dosimetry-to-verify-imrt-planar-dose-distribution-for-the-as1200-epid-and-fff-beams
#6
Narges Miri, Peter Keller, Benjamin J Zwan, Peter Greer
We proposed to perform a basic dosimetry commissioning on a new imager sys-tem, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for flattened (FF) and flattening filter-free (FFF) beams, then to develop an image-based quality assurance (QA) model for verification of the system delivery accuracy for intensity-modulated radiation therapy (IMRT) treat-ments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929491/validation-of-an-improved-helical-diode-array-and-dose-reconstruction-software-using-tg-244-datasets-and-stringent-dose-comparison-criteria
#7
Saeed Ahmed, Benjamin Nelms, Jakub Kozelka, Geoffrey Zhang, Eduardo Moros, Vladimir Feygelman
The original helical ArcCHECK (AC) diode array and associated software for 3D measurement-guided dose reconstruction were characterized and validated; however, recent design changes to the AC required that the subject be revisited. The most important AC change starting in 2014 was a significant reduction in the overresponse of diodes to scattered radiation outside of the direct beam, accom-plished by reducing the amount of high-Z materials adjacent to the diodes. This change improved the diode measurement accuracy, but in the process invalidated the dose reconstruction models that were assembled based on measured data acquired with the older version of the AC...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929490/rounded-leaf-end-modeling-in-pinnacle-vmat-treatment-planning-for-fixed-jaw-linacs
#8
Lori A Young, Fei Yang, Ning Cao, Juergen Meyer
During volume-modulated arc therapies (VMAT), dosimetric errors are introduced by multiple open dynamic leaf gaps that are present in fixed diaphragm linear accelerators. The purpose of this work was to develop a methodology for adjusting the rounded leaf end modeling parameters to improve out-of-field dose agreement in SmartArc VMAT treatment plans delivered by fixed jaw linacs where leaf gap dose is not negligible. Leaf gap doses were measured for an Elekta beam modulator linac with 0.4 cm micro-multileaf collimators (MLC) using an A16 micro-ionization chamber, a MatriXX ion chamber detector array, and Kodak EDR2 film dosimetry in a solid water phantom...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929485/difference-in-performance-between-3d-and-4d-cbct-for-lung-imaging-a-dose-and-image-quality-analysis
#9
Sheeba Thengumpallil, Kathleen Smith, Pascal Monnin, Jean Bourhis, François Bochud, Raphaël Moeckli
The study was to describe and to compare the performance of 3D and 4D CBCT imaging modalities by measuring and analyzing the delivered dose and the image quality. The 3D (Chest) and 4D (Symmetry) CBCT Elekta XVI lung IGRT protocols were analyzed. Dose profiles were measured with TLDs inside a dedicated phantom. The dosimetric indicator cone-beam dose index (CBDI) was evaluated. The image quality analysis was performed by assessing the contrast transfer function (CTF), the noise power spectrum (NPS) and the noise-equivalent quanta (NEQ)...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27927546/new-eos-imaging-protocol-allows-a-substantial-reduction-in-radiation-exposure-for-scoliosis-patients
#10
Peter O Newton, Yash Khandwala, Carrie E Bartley, Fredrick G Reighard, Tracey P Bastrom, Burt Yaszay
STUDY DESIGN: Prospective. OBJECTIVE: To evaluate the reliability of three-dimensional (3D) spinal models from Micro Dose EOS x-rays compared to standard, Low Dose EOS x-rays utilized for evaluating patients with adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: There is a strong suggestion that radiation exposure to scoliosis patients can be further reduced. METHODS: Sixty AIS patients who received biplanar, posteroanterior, and lateral standard Low Dose spine x-rays in our EOS imaging unit (∼0...
March 2016: Spine Deformity
https://www.readbyqxmd.com/read/27927068/beetroot-beta-vulgaris-rescues-mice-from-%C3%AE-ray-irradiation-by-accelerating-hematopoiesis-and-curtailing-immunosuppression
#11
Jinhee Cho, So Jin Bing, Areum Kim, Nam Ho Lee, Sang-Hee Byeon, Gi-Ok Kim, Youngheun Jee
CONTEXT: Beetroot [Beta vulgaris Linné (Chenopodiaceae)], a vegetable usually consumed as a food or a medicinal plant in Europe, has been reported to have antioxidant and anti-inflammatory properties. Since the lymphohematopoietic system is the most sensitive tissue to ionizing radiation, protecting it from radiation damage is one of the best ways to decrease detrimental effects from radiation exposure. OBJECTIVE: In this study, we evaluated the radio-protective effects of beetroot in hematopoietic stem cells (HSCs) and progenitor cells...
December 2017: Pharmaceutical Biology
https://www.readbyqxmd.com/read/27925774/influence-of-backscatter-radiation-on-cranial-reconstruction-implants
#12
Yoshiaki Sakamoto, Naoyoshi Koike, Hideyuki Takei, Mari Ohno, Tomoru Miwa, Kazunari Yoshida, Naoyuki Shigematsu, Kazuo Kishi
OBJECTIVES: We aimed to evaluate backscatter dose variations in different cranial bone implant materials in an experimental model designed to simulate postoperative radiotherapy. METHODS: We assessed the radiation backscatter doses associated with sheet and mesh type titanium plates and hydroxyapatite (HAP) samples (porosity, 35%, 50%, and 85%). The samples were irradiated with 6 MV and 10 MV photon beams from a linear accelerator. Measurements were obtained using an ionization chamber and radiochromic films cut from the same batch...
December 7, 2016: British Journal of Radiology
https://www.readbyqxmd.com/read/27925466/a-prospective-evaluation-of-contrast-and-radiation-dose-and-image-quality-in-cardiac-ct-in-children-with-complex-congenital-heart-disease-using-low-concentration-iodinated-contrast-agent-and-low-tube-voltage-and-current
#13
Qiao-Ru Hou, Wei Gao, Yu Min Zhong, Ai Min Sun, Qian Wang, Hai Sheng Qiu, Fang Wang, Jian Ying Li, Liwei Hu
OBJECTIVE: To assess image quality, contrast dose and radiation dose in cardiac CT in children with congenital heart disease using low-concentration iodinated contrast agent and low tube voltage and current in comparison with standard-dose protocol. METHODS: 110 patients with congenital heart disease were randomized to one of the two scan protocols: Group A (n=45) with 120mA tube current and contrast agent of 270mgI/ml in concentration (Visipaque, GE Healthcare), and Group B (n=65) with the conventional 160mA and 370mgI/mL concentration contrast (Iopamiro, Bracco)...
December 7, 2016: British Journal of Radiology
https://www.readbyqxmd.com/read/27922831/comprehensive-monte-carlo-study-of-patient-doses-from-cone-beam-ct-imaging-in-radiotherapy
#14
T E Marchant, K D Joshi
Accurate knowledge of ionizing radiation dose from cone-beam CT (CBCT) imaging in radiotherapy is important to allow concomitant risks to be estimated and for justification of imaging exposures. This study uses a Monte Carlo CBCT model to calculate imaging dose for a wide range of imaging protocols for male and female patients. The Elekta XVI CBCT system was modeled using GATE and simulated doses were validated against measurements in a water tank and thorax phantom. Imaging dose was simulated in the male and female ICRP voxel phantoms for a variety of anatomical sites and imager settings (different collimators, filters, full and partial rotation)...
December 6, 2016: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/27919623/assessment-of-the-neutron-dose-field-around-a-biomedical-cyclotron-fluka-simulation-and-experimental-measurements
#15
Angelo Infantino, Gianfranco Cicoria, Giulia Lucconi, Davide Pancaldi, Sara Vichi, Federico Zagni, Domiziano Mostacci, Mario Marengo
In the planning of a new cyclotron facility, an accurate knowledge of the radiation field around the accelerator is fundamental for the design of shielding, the protection of workers, the general public and the environment. Monte Carlo simulations can be very useful in this process, and their use is constantly increasing. However, few data have been published so far as regards the proper validation of Monte Carlo simulation against experimental measurements, particularly in the energy range of biomedical cyclotrons...
December 2, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27917826/improved-radiation-dose-efficiency-in-solution-saxs-using-a-sheath-flow-sample-environment
#16
Nigel Kirby, Nathan Cowieson, Adrian M Hawley, Stephen T Mudie, Duncan J McGillivray, Michael Kusel, Vesna Samardzic-Boban, Timothy M Ryan
Radiation damage is a major limitation to synchrotron small-angle X-ray scattering analysis of biomacromolecules. Flowing the sample during exposure helps to reduce the problem, but its effectiveness in the laminar-flow regime is limited by slow flow velocity at the walls of sample cells. To overcome this limitation, the coflow method was developed, where the sample flows through the centre of its cell surrounded by a flow of matched buffer. The method permits an order-of-magnitude increase of X-ray incident flux before sample damage, improves measurement statistics and maintains low sample concentration limits...
December 1, 2016: Acta Crystallographica. Section D, Structural Biology
https://www.readbyqxmd.com/read/27916923/associations-between-meteorological-factors-and-aseptic-meningitis-in-six-metropolitan-provinces-of-the-republic-of-korea
#17
Yadav Prasad Joshi, Eun-Hye Kim, Jong-Hun Kim, Ho Kim, Hae-Kwan Cheong
We assessed the association between climate factors and a number of aseptic meningitis cases in six metropolitan provinces of the Republic of Korea using a weekly number of cases from January 2002 to December 2012. Generalized linear quasi-Poisson models were applied to estimate the effects of climate factors on the weekly number of aseptic meningitis cases. We used generalized additive and generalized additive mixed models to assess dose-response relationships. A 1 °C increase in mean temperature was associated with an 11...
November 30, 2016: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/27914781/incident-air-kerma-to-absorbed-organ-dose-conversion-factors-for-breast-and-lung-in-pa-thorax-radiography-the-effect-of-patient-thickness-and-radiation-quality
#18
A Kelaranta, P Toroi, P Vock
PURPOSE: Converting the measurable quantities to patient organ doses in projection radiography is usually based on a standard-sized patient model and a specific radiation quality, which are likely to differ from the real situation. Large inaccuracies can therefore be obtained in organ doses, because organ doses are dependent on the exposure parameters, exposure geometry and patient anatomy. In this study, the effect of radiation quality and patient thickness on the organ dose conversion factors were determined...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27913582/bremsstrahlung-dose-yield-for-high-intensity-short-pulse-laser-solid-experiments
#19
Taiee Liang, Johannes M Bauer, James C Liu, Sayed H Rokni
A bremsstrahlung source term has been developed by the Radiation Protection (RP) group at SLAC National Accelerator Laboratory for high-intensity short-pulse laser-solid experiments between 10(17) and 10(22) W cm(-2) This source term couples the particle-in-cell plasma code EPOCH and the radiation transport code FLUKA to estimate the bremsstrahlung dose yield from laser-solid interactions. EPOCH characterizes the energy distribution, angular distribution, and laser-to-electron conversion efficiency of the hot electrons from laser-solid interactions, and FLUKA utilizes this hot electron source term to calculate a bremsstrahlung dose yield (mSv per J of laser energy on target)...
December 1, 2016: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/27910825/monte-carlo-studies-on-water-and-lif-cavity-properties-for-dose-reporting-quantities-when-using-x-ray-and-brachytherapy-sources
#20
Isabela Soares Lopes Branco, Paula Cristina Guimarães Antunes, Gabriel Paiva Fonseca, Hélio Yoriyaz
Model-based dose calculation algorithms (MBDCAs) are the current tools to estimate dose in brachytherapy, which takes into account heterogeneous medium, therefore, departing from water-based formalism (TG-43). One aspect associated to MBCDA is the choice of dose specification medium since it offers two possibilities to report dose: (a) dose to medium in medium, D m,m; and (b) dose to water in medium, D w,m. The discussion about the preferable quantity to be reported is underway. The dose conversion factors, DCF, between dose to water in medium, D w,m, and dose to medium in medium, D m,m, is based on cavity theory and can be obtained using different approaches...
December 21, 2016: Physics in Medicine and Biology
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