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radiation dosimetry

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https://www.readbyqxmd.com/read/28325236/improving-quality-and-access-to-radiation-therapy-an-iaea-perspective
#1
REVIEW
May Abdel-Wahab, Eduardo Zubizarreta, Alfredo Polo, Ahmed Meghzifene
The International Atomic Energy Agency (IAEA) has been involved in radiation therapy since soon after its creation in 1957. In response to the demands of Member States, the IAEA׳s activities relating to radiation therapy have focused on supporting low- and middle-income countries to set up radiation therapy facilities, expand the scope of treatments, or gradually transition to new technologies. In addition, the IAEA has been very active in providing internationally harmonized guidelines on clinical, dosimetry, medical physics, and safety aspects of radiation therapy...
April 2017: Seminars in Radiation Oncology
https://www.readbyqxmd.com/read/28302759/preclinical-evaluation-of-11-c-sarcosine-as-a-substrate-of-proton-coupled-amino-acid-transporters-and-first-human-application-in-prostate-cancer
#2
Morand Piert, Xia Shao, David M Raffel, Mathew S Davenport, Jeffrey Montgomery, Lakshmi Kunju, Brian G Hockley, Javed Siddiqui, Peter J H Scott, Arul Chinnaiyan, Thekkelnaycke Rajandiran
Sarcosine is a known substrate of proton-coupled amino acid transporters (PAT), which are overexpressed in selected tissues and solid tumors. Sarcosine, an N-methyl derivative of the amino acid glycine and a metabolic product of choline, plays an important role for prostate cancer aggressiveness and progression. Methods: Carbon-11 radiolabeled sarcosine ((11)C-sarcosine) was tested as a new positron emission tomography (PET) imaging probe in comparison with (11)C-choline in two prostate cancer tumor xenograft models (DU-145 and PC-3)...
March 16, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28302144/a-dosimetric-model-for-the-heterogeneous-delivery-of-radioactive-nanoparticles-in-vivo-a-feasibility-study
#3
Andrew B Satterlee, Peter Attayek, Bentley Midkiff, Leaf Huang
ᅟ: Accurate and quantitative dosimetry for internal radiation therapy can be especially challenging, given the heterogeneity of patient anatomy, tumor anatomy, and source deposition. Internal radiotherapy sources such as nanoparticles and monoclonal antibodies require high resolution imaging to accurately model the heterogeneous distribution of these sources in the tumor. The resolution of nuclear imaging modalities is not high enough to measure the heterogeneity of intratumoral nanoparticle deposition or intratumoral regions, and mathematical models do not represent the actual heterogeneous dose or dose response...
March 17, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28300383/dosimetry-analysis-of-panoramic-imaging-devices-in-different-sized-phantoms
#4
Muizz A Wahid, Ella Choi, David S MacDonald, Nancy L Ford
The aim of this study is to measure the radiographic dose in adult, adolescent, and child head-sized PMMA phantoms for three panoramic-imaging devices: the panoramic mode on two CBCT machines (Carestream 9300 and i-CAT NG) and the Planmeca ProMax 2D. A SEDENTEXCT dose index adult phantom and custom-built adolescent and pediatric PMMA dosimetry phantoms were used. Panoramic radiographs were performed using a Planmeca ProMax 2D and the panoramic mode on a Carestream 9300 CBCT and an i-CAT NG using the protocols used clinically...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300380/dosimetric-characteristics-of-linatech-dmlc-h-multi-leaf-collimator-monte-carlo-simulation-and-experimental-study
#5
Mikaeil Molazadeh, Ahad Zeinali, Mostafa Robatjazi, Alireza Shirazi, Ghazale Geraily
This study evaluated the basic dosimetric characteristics of a Dynamic Multi Leaf Collimator (DMLC) using a diode detector and film measurements for Intensity Modulated Radiation Therapy Quality Assurance (IMRT QA). The EGSnrc Monte Carlo (MC) simulation system was used for the determination of MLC characteristics. Radiation transmission and abutting leaf leakage relevant to the LinaTech DMLC H were measured using an EDGE detector and EBT3 film. In this study, the BEAMnrc simulation code was used for modeling...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297422/a-methodology-for-on-board-cbct-imaging-dose-using-optically-stimulated-luminescence-detectors
#6
Noor Mail, Muhammad Yusuf, Nazeeh Alothmany, A Abdulrahman Kinsara, Fahad Abdulkhaliq, Suliman M Ghamdi, Abdelhamid Saoudi
Cone-beam computed tomography CBCT systems are used in radiation therapy for patient alignment and positioning. The CBCT imaging procedure for patient setup adds substantial radiation dose to patient's normal tissue. This study presents a complete procedure for the CBCT dosimetry using the InLight optically-stimulated-luminescence (OSL) nanoDots. We report five dose parameters: the mean slice dose (DMSD); the cone beam dose index (CBDIW); the mean volume dose (DMVD); point-dose profile, D(FOV); and the off-field Dose...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297420/thin-film-cdte-detector-for-microdosimetric-study-of-radiation-dose-enhancement-at-gold-tissue-interface
#7
Nava Raj Paudel, Diana Shvydka, E Ishmael Parsai
Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of the dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297338/epid-based-in-vivo-dosimetry-system-clinical-experience-and-results
#8
Sofia Celi, Emilie Costa, Claas Wessels, Alejandro Mazal, Alain Fourquet, Pascal Francois
Mandatory in several countries, in vivo dosimetry has been recognized as one of the next milestones in radiation oncology. Our department has implemented clinically an EPID based in vivo dosimetry system, EPIgray, by DOSISOFT S.A., since 2006. An analysis of the measurements per linac and energy over a two-year period was performed, which included a more detailed examination per technique and treatment site over a six-month period. A comparison of the treatment planning system doses and the doses estimated by EPIgray shows a mean of the differences of 1...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297320/vmat-linear-accelerator-commissioning-and-quality-assurance-dose-control-and-gantry-speed-tests
#9
Michael P Barnes, Pejman Rowshanfarzad, Peter B Greer
In VMAT treatment delivery the ability of the linear accelerator (linac) to accurately control dose versus gantry angle is critical to delivering the plan correctly. A new VMAT test delivery was developed to specifically test the dose versus gantry angle with the full range of allowed gantry speeds and dose rates. The gantry-mounted IBA MatriXX with attached inclinometer was used in movie mode to measure the instantaneous relative dose versus gantry angle during the plan every 0.54 s. The results were compared to the expected relative dose at each gantry angle calculated from the plan...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297306/epid-based-dosimetry-to-verify-imrt-planar-dose-distribution-for-the-as1200-epid-and-fff-beams
#10
Narges Miri, Peter Keller, Benjamin J Zwan, Peter Greer
We proposed to perform a basic dosimetry commissioning on a new imager system, 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) treatments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297276/rounded-leaf-end-modeling-in-pinnacle-vmat-treatment-planning-for-fixed-jaw-linacs
#11
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 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296327/fricke-gel-dosimeter-with-improved-sensitivity-for-low-dose-level-measurements
#12
Mauro Vaiente, Wladimir Molina, Lila Carrizales Silva, Rodolfo Figueroa, Francisco Malano, Pedro Pérez, Mauricio Santibañez, José Vedelago
Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue-equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, independence of dose rate and incident direction, as well as linear dose response. This work presents the development and characterization of an improved Fricke gel system, based on modified chemical compositions, making possible its application in clinical radiology due to its improved sensitivity...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296294/electrocardiogram-gated-coronary-ct-angiography-dose-estimates-using-impact
#13
Masanao Kobayashi, Yasuki Asada, Kosuke Matsubara, Shouichi Suzuki, Kichiro Koshida, Yuta Matsunaga, Tomonobu Haba, Ai Kawaguchi, Hiroshi Toyama, Ryoichi Kato
The primary study objective was to assess radiation doses using a modified form of the Imaging Performance Assessment of Computed Tomography (CT) scanner (ImPACT) patient dosimetry for cardiac applications on an Aquilion ONE ViSION Edition scanner, including the Ca score, target computed tomography angiography (CTA), prospective CTA, continuous CTA/cardiac function analysis (CFA), and CTA/CFA modulation. Accordingly, we clarified the CT dose index (CTDI) to determine the relationship between heart rate (HR) and X-ray exposure...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28291939/pixel-response-based-epid-dosimetry-for-patient-specific-qa
#14
Bin Han, Aiping Ding, Minghui Lu, Lei Xing
Increasing use of high dose rate, flattening filter free (FFF), and/or small-sized field beams presents a significant challenge to the medical physics community. In this work, we develop a strategy of using a high spatial resolution and high frame rate amorphous silicon flat panel electronic portal imaging device (EPID) for dosimetric measurements of these challenging cases, as well as for conventional external beam therapy. To convert a series of raw EPID-measured radiation field images into water-based dose distribution, a pixel-to-pixel dose-response function of the EPID specific to the linac is essential...
January 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28291159/67cu-radiolabeling-of-a-multimeric-rgd-peptide-for-%C3%AE-v%C3%AE-3-integrin-targeted-radionuclide-therapy-stability-therapeutic-efficacy-and-safety-studies-in-mice
#15
Zhao-Hui Jin, Takako Furukawa, Tomoyuki Ohya, Mélissa Degardin, Aya Sugyo, Atsushi B Tsuji, Yasuhisa Fujibayashi, Ming-Rong Zhang, Tatsuya Higashi, Didier Boturyn, Pascal Dumy, Tsuneo Saga
OBJECTIVE: Copper-67 (Cu) is one of the most promising radionuclides for internal radiation therapy. Globally, several projects have recently been initiated for developing innovative approaches for the large-scale production of Cu. Encouraged by these, we performed Cu-radiolabeling of a tetrameric cyclic Arg-Gly-Asp (cRGD) peptide conjugate, cyclam-RAFT-c(-RGDfK-)4, which selectively targets αVβ3 integrin (αVβ3), the transmembrane receptor involved in tumor invasion, angiogenesis, and metastasis...
April 2017: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/28290334/gonad-dose-in-ap-pelvis-radiography-impact-of-anode-heel-orientation
#16
H A A B Mraity, A England, P Hogg
PURPOSE: For antero posterior (AP) pelvis radiographic examination, determine the impact of anode heel orientation on female/male gonad dose. METHODS: High sensitivity thermo-luminescent dosimeters (TLDs) were used with an ATOM dosimetry phantom; the phantom was positioned for AP pelvis. TLDs were placed into the testes and ovaries. Radiation dose received by these organs was measured with the feet toward anode and feet toward the cathode. kVp, mAs and SID were manipulated to generate a range of exposures...
February 2017: Radiography
https://www.readbyqxmd.com/read/28288658/prostate-cancer-treated-with-brachytherapy-an-exploratory-study-of-dose-dependent-biomarkers-and-quality-of-life
#17
Sarah O S Osman, Simon Horn, Darren Brady, Stephen J McMahon, Ahamed B Mohamed Yoosuf, Darren Mitchell, Karen Crowther, Ciara A Lyons, Alan R Hounsell, Kevin M Prise, Conor K McGarry, Suneil Jain, Joe M O'Sullivan
BACKGROUND: Low-dose-rate permanent prostate brachytherapy (PPB) is an attractive treatment option for patients with localised prostate cancer with excellent outcomes. As standard CT-based post-implant dosimetry often correlates poorly with late treatment-related toxicity, this exploratory (proof of concept) study was conducted to investigate correlations between radiation - induced DNA damage biomarker levels, and acute and late bowel, urinary, and sexual toxicity. METHODS: Twelve patients treated with (125)I PPB monotherapy (145Gy) for prostate cancer were included in this prospective study...
March 14, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28284122/the-importance-of-bmi-in-dosimetry-of-153-sm-edtmp-bone-pain-palliation-therapy-a-monte-carlo-study
#18
Maryam Fallahpoor, Mehrshad Abbasi, Ali Asghar Parach, Faraz Kalantari
Using digital phantoms as an atlas compared to acquiring CT data for internal radionuclide dosimetry decreases patient overall radiation dose and reduces the required analysis effort and time for organ segmentation. The drawback is that the phantom may not match exactly with the patient. We assessed the effect of varying BMIs on dosimetry results for a bone pain palliation agent, (153)Sm-EDTMP. The simulation was done using the GATE Monte Carlo code. Female XCAT phantoms with the following different BMIs were employed: 18...
February 28, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28283750/the-effects-of-simulating-a-realistic-eye-model-on-the-eye-dose-of-an-adult-male-undergoing-head-computed-tomography
#19
Parisa Akhlaghi, Atiyeh Ebrahimi-Khankook, Alireza Vejdani-Noghreiyan
In head computed tomography, radiation upon the eye lens (as an organ with high radiosensitivity) may cause lenticular opacity and cataracts. Therefore, quantitative dose assessment due to exposure of the eye lens and surrounding tissue is a matter of concern. For this purpose, an accurate eye model with realistic geometry and shape, in which different eye substructures are considered, is needed. To calculate the absorbed radiation dose of visual organs during head computed tomography scans, in this study, an existing sophisticated eye model was inserted at the related location in the head of the reference adult male phantom recommended by the International Commission on Radiological Protection (ICRP)...
March 10, 2017: Radiation and Environmental Biophysics
https://www.readbyqxmd.com/read/28274404/in-vivo-dosimetry-with-optically-stimulated-luminescent-dosimeters-for-conformal-and-intensity-modulated-radiation-therapy-a-2-year-multicenter-cohort-study
#20
Adam C Riegel, Yu Chen, Ajay Kapur, Laura Apicello, Abraham Kuruvilla, Anthony J Rea, Abolghassem Jamshidi, Louis Potters
PURPOSE: Optically stimulated luminescent dosimeters (OSLDs) are utilized for in vivo dosimetry (IVD) of modern radiation therapy techniques such as intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Dosimetric precision achieved with conventional techniques may not be attainable. In this work, we measured accuracy and precision for a large sample of clinical OSLD-based IVD measurements. METHODS AND MATERIALS: Weekly IVD measurements were collected from 4 linear accelerators for 2 years and were expressed as percent differences from planned doses...
March 2017: Practical Radiation Oncology
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