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https://www.readbyqxmd.com/read/27910025/cytogenetics-for-biological-dosimetry
#1
Michelle Ricoul, Tamizh Gnana-Sekaran, Laure Piqueret-Stephan, Laure Sabatier
Cytogenetics is the gold-standard in biological dosimetry for assessing a received dose of ionizing radiation. More modern techniques have recently emerged, but none are as specific as cytogenetic approaches, particularly the dicentric assay. Here, we will focus on the principal cytogenetic techniques used for biological dosimetry: the dicentric assay in metaphase cells, the micronuclei assay in binucleated cells, and the premature condensed chromosome (PCC) assay in interphase cells. New fluorescence in situ hybridization (FISH) techniques (such as telomere-centromere hybridization) have facilitated the analysis of the dicentric assay and have permitted to assess the dose a long time after irradiation by translocation analysis (such as by Tri-color FISH or Multiplex-FISH)...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27908503/cobalt-60-machines-and-medical-linear-accelerators-competing-technologies-for-external-beam-radiotherapy
#2
B J Healy, D van der Merwe, K E Christaki, A Meghzifene
Medical linear accelerators (linacs) and cobalt-60 machines are both mature technologies for external beam radiotherapy. A comparison is made between these two technologies in terms of infrastructure and maintenance, dosimetry, shielding requirements, staffing, costs, security, patient throughput and clinical use. Infrastructure and maintenance are more demanding for linacs due to the complex electric componentry. In dosimetry, a higher beam energy, modulated dose rate and smaller focal spot size mean that it is easier to create an optimised treatment with a linac for conformal dose coverage of the tumour while sparing healthy organs at risk...
November 28, 2016: Clinical Oncology: a Journal of the Royal College of Radiologists
https://www.readbyqxmd.com/read/27908385/the-mutagenic-assessment-of-an-electronic-cigarette-and-reference-cigarette-smoke-using-the-ames-assay-in-strains-ta98-and-ta100
#3
D Thorne, I Crooks, M Hollings, A Seymour, C Meredith, M Gaca
Salmonella typhimurium strains TA98 and TA100 were used to assess the mutagenic potential of the aerosol from a commercially available, rechargeable, closed system electronic-cigarette. Results obtained were compared to those for the mainstream smoke from a Kentucky reference (3R4F) cigarette. Two different test matrices were assessed. Aerosol generated from the e-cigarette was trapped on a Cambridge filter pad, eluted in DMSO and compared to cigarette smoke total particulate matter (TPM), which was generated in the same manner for mutagenicity assessment in the Salmonella assay...
December 2016: Mutation Research
https://www.readbyqxmd.com/read/27908188/polymer-gel-dosimetry-for-measuring-the-dose-near-thin-high-z-materials-irradiated-with-high-energy-photon-beams
#4
Leighton L Warmington, N Gopishankar, John H Broadhurst, Yoichi Watanabe
PURPOSE: To investigate the feasibility of three-dimensional (3D) dose measurements near thin high-Z materials placed in a water-like medium by using a polymer gel dosimeter (PGD) when the medium was irradiated with high energy photon beams. METHODS: PGD is potentially a useful tool for this application because it can record the dose around a small object made of a high-Z material in a continuous 3D medium. In this study, the authors manufactured a methacrylic acid-based normoxic PGD, nMAG...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908182/prostate-deformation-from-inflatable-rectal-probe-cover-and-dosimetric-effects-in-prostate-seed-implant-brachytherapy
#5
Jun Lian, Yeqin Shao, Larry D Potter, Ronald C Chen, Jordan A Holmes, Eleanor A Pryser, Jie Shen, Dinggang Shen, Andrew Z Wang
PURPOSE: Prostate brachytherapy is an important treatment technique for patients with localized prostate cancer. An inflatable rectal ultrasound probe cover is frequently utilized during the procedure to adjust for unfavorable prostate position relative to the implant grid. However, the inflated cover causes prostate deformation, which is not accounted for during dosimetric planning. Most of the therapeutic dose is delivered after the procedure when the prostate and surrounding organs-at-risk are less deformed...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908181/defining-and-assessing-an-anisotropic-delineation-margin-for-modern-radiotherapy
#6
L R Bell, E M Pogson, P E Metcalfe, L C Holloway
PURPOSE: Uncertainty in target volume delineation for modern radiotherapy impacts dosimetry and patient outcomes. Delineation uncertainty is generally overlooked in practice as a source of error, potentially since historically, other uncertainties have been the main focus. This work defined and assessed an anisotropic delineation margin in both polar and spherical coordinate systems in order to account for the spatially varying nature of this uncertainty using a whole breast radiotherapy cohort as a proof of concept...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908170/high-resolution-digital-autoradiographic-and-dosimetric-analysis-of-heterogeneous-radioactivity-distribution-in-xenografted-prostate-tumors
#7
Oskar V Timmermand, Jenny Nilsson, Sven-Erik Strand, Jörgen Elgqvist
PURPOSE: The first main aim of this study was to illustrate the absorbed dose rate distribution from (177)Lu in sections of xenografted prostate cancer (PCa) tumors using high resolution digital autoradiography (DAR) and compare it with hypothetical identical radioactivity distributions of (90)Y or 7 MeV alpha-particles. Three dosimetry models based on either dose point kernels or Monte Carlo simulations were used and evaluated. The second and overlapping aim, was to perform DAR imaging and dosimetric analysis of the distribution of radioactivity, and hence the absorbed dose rate, in tumor sections at an early time point after injection during radioimmunotherapy using (177)Lu-h11B6, directed against the human kallikrein 2 antigen...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908161/technical-note-magnetic-field-effects-on-gafchromic-film-response-in-mr-igrt
#8
Francisco J Reynoso, Austen Curcuru, Olga Green, Sasa Mutic, Indra J Das, Lakshmi Santanam
PURPOSE: Magnetokinetic changes may affect crystal orientation and polymerization within the active layer of radiochromic film (RCF). This effect is investigated in a magnetic resonance image-guided radiotherapy unit within the context of film dosimetry. METHODS: Gafchromic EBT2 RCF was irradiated in a 30 × 30 × 30 cm(3) solid water phantom using a Co-60 MRI guided radiotherapy system (B = 0.35 T) under normal operating conditions, and under the exact conditions and setup without a magnetic field...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908159/a-preclinical-microbeam-facility-with-a-conventional-x-ray-tube
#9
Stefan Bartzsch, Craig Cummings, Stephan Eismann, Uwe Oelfke
PURPOSE: Microbeam radiation therapy is an innovative treatment approach in radiation therapy that uses arrays of a few tens of micrometer wide and a few hundreds of micrometer spaced planar x-ray beams as treatment fields. In preclinical studies these fields efficiently eradicated tumors while normal tissue could effectively be spared. However, development and clinical application of microbeam radiation therapy is impeded by a lack of suitable small scale sources. Until now, only large synchrotrons provide appropriate beam properties for the production of microbeams...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908149/real-time-electromagnetic-seed-drop-detection-for-permanent-implants-brachytherapy-technology-overview-and-performance-assessment
#10
E Racine, G Hautvast, D Binnekamp, L Beaulieu
PURPOSE: To describe the principles and report on the performance of a novel real-time electromagnetic (EM) seed drop detection technology for permanent implants brachytherapy procedures. METHODS: A novel EM hollow needle prototype was recently developed by Philips. It possesses standard 3D tracking capability as well as a seed drop detection mechanism, both performed from a single custom built EM sensor. The detection mechanism is based on the magnetic permeability changes in the sensor as the seeds pass through...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908147/strategies-for-ct-tissue-segmentation-for-monte-carlo-calculations-in-nuclear-medicine-dosimetry
#11
P E N Braad, T Andersen, S B Hansen, P F Høilund-Carlsen
PURPOSE: CT images are used for patient specific Monte Carlo treatment planning in radionuclide therapy. The authors investigated the impact of tissue classification, CT image segmentation, and CT errors on Monte Carlo calculated absorbed dose estimates in nuclear medicine. METHODS: CT errors as a function of patient size, CT reconstruction, and tube current modulation methods were assessed in a phantom experiment on a clinical CT system. The impact of tissue segmentation methods and CT number variations on EGSnrc Monte Carlo calculated absorbed dose distributions was assessed for (99m)Tc and (131)I in the ICRP/ICRU male phantom and in a patient PET/CT-scanned with (124)I prior to radioiodine therapy...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27906788/ds02r1-improvements-to-atomic-bomb-survivors-input-data-and-implementation-of-dosimetry-system-2002-ds02-and-resulting-changes-in-estimated-doses
#12
H M Cullings, E J Grant, S D Egbert, T Watanabe, T Oda, F Nakamura, T Yamashita, H Fuchi, S Funamoto, K Marumo, R Sakata, Y Kodama, K Ozasa, K Kodama
Individual dose estimates calculated by Dosimetry System 2002 (DS02) for the Life Span Study (LSS) of atomic bomb survivors are based on input data that specify location and shielding at the time of the bombing (ATB). A multi-year effort to improve information on survivors' locations ATB has recently been completed, along with comprehensive improvements in their terrain shielding input data and several improvements to computational algorithms used in combination with DS02 at RERF. Improvements began with a thorough review and prioritization of original questionnaire data on location and shielding that were taken from survivors or their proxies in the period 1949-1963...
January 2017: Health Physics
https://www.readbyqxmd.com/read/27906782/predicting-heart-dose-in-breast-cancer-patients-who-received-3d-conformal-radiation-therapy
#13
Daniel Wollschläger, Heiko Karle, Marcus Stockinger, Detlef Bartkowiak, Sandra Bührdel, Hiltrud Merzenich, Thomas Wiegel, Heinz Schmidberger, Maria Blettner
Cardiac late effects are a major health concern for long-term survivors after radiotherapy for breast cancer. Large cohort studies to better understand the exact dose-response relationship require individual estimates of radiation dose to the heart. To predict individual cardiac dose from information that is typically available for all members of a retrospective epidemiological cohort study, 774 female breast cancer patients treated with megavoltage tangential field radiotherapy in 1998-2008 were examined. All dose distributions were calculated using Eclipse with the anisotropic analytical algorithm (AAA) for photon fields and the electron Monte Carlo algorithm for electron boost fields...
January 2017: Health Physics
https://www.readbyqxmd.com/read/27904871/in-vivo-measurement-and-characterization-of-a-novel-formulation-of-177-lu-dota-octreotate
#14
Dale L Bailey, Thomas M Hennessy, Kathy P Willowson, E Courtney Henry, David Lh Chan, Alireza Aslani, Paul J Roach
OBJECTIVES: Lutetium-177 can be made with high specific activity and with no other isotopes of lutetium present, referred to as "No Carrier Added" (NCA) (177)Lu. We have radiolabelled DOTA-conjugated peptide DOTA-(Tyr(3))-octreotate with NCA (177)Lu ("NCA-LuTATE") and used it in nearly 40 therapeutic administrations for subjects with neuroendocrine tumours or meningiomas. In this paper, we report on our initial studies on aspects of the biodistribution and dosimetry of NCA-LuTATE from gamma camera 2D whole body (WB) and quantitative 3D SPECT (qSPECT) (177)Lu imaging...
2016: Asia Oceania Journal of Nuclear Medicine & Biology
https://www.readbyqxmd.com/read/27897136/an-image-based-skeletal-dosimetry-model-for-the-icrp-reference-adult-female-internal-electron-sources
#15
Shannon E O'Reilly, Lindsay S DeWeese, Matthew R Maynard, Didier A Rajon, Michael B Wayson, Emily L Marshall, Wesley E Bolch
An image-based skeletal dosimetry model for internal electron sources was created for the ICRP-defined reference adult female. Many previous skeletal dosimetry models, which are still employed in commonly used internal dosimetry software, do not properly account for electron escape from trabecular spongiosa, electron cross-fire from cortical bone, and the impact of marrow cellularity on active marrow self-irradiation. Furthermore, these existing models do not employ the current ICRP definition of a 50 µm bone endosteum (or shallow marrow)...
December 21, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27896673/the-clinical-safety-biodistribution-and-internal-radiation-dosimetry-of-18-f-ah113804-in-healthy-adult-volunteers
#16
E J Somer, R Owenius, A Wall, G Antoni, A Thibblin, J Sörensen
BACKGROUND: Quantitative biodistribution, venous blood and excretion data have been obtained following the intravenous bolus injection of AH113804 ((18)F) Injection in six healthy volunteers (HVs), four males and two females, up to approximately 5 h post-injection. For each subject, key organs and tissues were delineated and analytical fits were made to the image data as functions of time to yield the normalised cumulated activities. These were input to an internal radiation dosimetry calculation based upon the Medical Internal Radiation Dose (MIRD) schema for the Cristy-Eckerman adult male or female phantom...
December 2016: EJNMMI Research
https://www.readbyqxmd.com/read/27895688/electromagnetic-tracking-for-treatment-verification-in-interstitial-brachytherapy
#17
REVIEW
Christoph Bert, Markus Kellermeier, Kari Tanderup
Electromagnetic tracking (EMT) is used in several medical fields to determine the position and orientation of dedicated sensors, e.g., attached to surgical tools. Recently, EMT has been introduced to brachytherapy for implant reconstruction and error detection. The manuscript briefly summarizes the main issues of EMT and error detection in brachytherapy. The potential and complementarity of EMT as treatment verification technology will be discussed in relation to in vivo dosimetry and imaging.
October 2016: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/27895684/investigation-of-the-gold-nanoparticles-effects-on-the-prostate-dose-distribution-in-brachytherapy-gel-dosimetry-and-monte-carlo-method
#18
Hossein Khosravi, Bijan Hashemi, Faezeh Rahmani, Ahmad Ebadi
PURPOSE: In this work, gold nanoparticles (GNPs) were embedded in the MAGIC-f polymer gel irradiated with the (192)Ir brachytherapy sources. MATERIAL AND METHODS: At the first plexiglas phantom was made as the human pelvis. The GNPs were synthesized with 15 nm in diameter and 0.1 mM (0.0197 mg/ml) in concentration by using a chemical reduction method. Then, the MAGIC-f gel was synthesized. The fabricated gel was poured into the tubes located at the prostate (with and without the GNPs) locations of the phantom...
October 2016: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/27895682/development-and-clinical-implementation-of-a-new-template-for-mri-based-intracavitary-interstitial-gynecologic-brachytherapy-for-locally-advanced-cervical-cancer-from-ct-based-mupit-to-the-mri-compatible-template-benidorm-ten-years-of-experience
#19
Silvia Rodríguez Villalba, Jose Richart Sancho, Antonio Otal Palacín, Jose Perez-Calatayud, Manuel Santos Ortega
PURPOSE: To study outcome and toxicity in 59 patients with locally advanced cervix carcinoma treated with computed tomography (CT)-based Martinez universal perineal interstitial template (MUPIT) and the new magnetic resonance imaging (MRI)-compatible template Benidorm (TB). MATERIAL AND METHODS: From December 2005 to October 2015, we retrospectively analyzed 34 patients treated with MUPIT and 25 treated with the TB. Six 4 Gy fractions were prescribed to the clinical target volume (CTV) combined with external beam radiotherapy (EBRT)...
October 2016: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/27895679/the-impact-of-body-mass-index-on-dosimetric-quality-in-low-dose-rate-prostate-brachytherapy
#20
Michelle I Echevarria, Arash O Naghavi, Puja S Venkat, Yazan A Abuodeh, Carlos Chevere, Kosj Yamoah
PURPOSE: Low-dose-rate (LDR) brachytherapy has been established as an effective and safe treatment option for men with low and intermediate risk prostate cancer. In this retrospective analysis, we sought to study the effect of body mass index (BMI) on post-implant dosimetric quality. MATERIAL AND METHODS: After institutional approval, records of patients with non-metastatic prostate cancer treated in Puerto Rico with LDR brachytherapy during 2008-2013 were reviewed...
October 2016: Journal of Contemporary Brachytherapy
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