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https://www.readbyqxmd.com/read/29626289/dosimetric-changes-with-computed-tomography-automatic-tube-current-modulation-techniques
#1
Sofia Spampinato, Anna Maria Gueli, Pietro Milone, Luigi Angelo Raffaele
The study is aimed at a verification of dose changes for a computed tomography automatic tube-current modulation (ATCM) technique. For this purpose, anthropomorphic phantom and Gafchromic® XR-QA2 films were used. Radiochromic films were cut according to the shape of two thorax regions. The ATCM algorithm is based on noise index (NI) and three exam protocols with different NI were chosen, of which one was a reference. Results were compared with dose values displayed by the console and with Poisson statistics...
April 6, 2018: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29609823/evaluation-of-a-led-based-flatbed-document-scanner-for-radiochromic-film-dosimetry-in-transmission-mode
#2
José Manuel Lárraga-Gutiérrez, Olivia Amanda García-Garduño, Carlos Treviño-Palacios, José Alfredo Herrera-González
Flatbed scanners are the most frequently used reading instrument for radiochromic film dosimetry because its low cost, high spatial resolution, among other advantages. These scanners use a fluorescent lamp and a CCD array as light source and detector, respectively. Recently, manufacturers of flatbed scanners replaced the fluorescent lamp by light emission diodes (LED) as a light source. The goal of this work is to evaluate the performance of a commercial flatbed scanner with LED based source light for radiochromic film dosimetry...
March 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29609815/monte-carlo-uncertainty-analysis-of-dose-estimates-in-radiochromic-film-dosimetry-with-single-channel-and-multichannel-algorithms
#3
Juan Antonio Vera-Sánchez, Carmen Ruiz-Morales, Antonio González-López
PURPOSE: To provide a multi-stage model to calculate uncertainty in radiochromic film dosimetry with Monte-Carlo techniques. This new approach is applied to single-channel and multichannel algorithms. MATERIAL AND METHODS: Two lots of Gafchromic EBT3 are exposed in two different Varian linacs. They are read with an EPSON V800 flatbed scanner. The Monte-Carlo techniques in uncertainty analysis provide a numerical representation of the probability density functions of the output magnitudes...
March 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29603564/film-based-dose-validation-of-monte-carlo-algorithm-for-cyberknife-system-with-a-cirs-thorax-phantom
#4
Yuxi Pan, Ruijie Yang, Jun Li, Xile Zhang, Lu Liu, Junjie Wang
Monte Carlo (MC) simulation, as the most accurate dose calculation algorithm, is available in the MultiPlan treatment planning system for Cyberknife. The main purpose of this work was to perform experiments to thoroughly investigate the accuracy of the MC dose calculation algorithm. Besides the basic MC beam commissioning, two test scenarios were designed. First, single beam tests were performed with a solid water phantom to verify the MC source model in simple geometry. Then, a lung treatment plan on a CIRS thorax phantom was created to mimic the clinical patient treatment...
March 30, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29571934/multi-institutional-evaluation-of-end-to-end-protocol-for-imrt-vmat-treatment-chains-utilizing-conventional-linacs
#5
Brian Loughery, Cory Knill, Evan Silverstein, Viatcheslav Zakjevskii, Kathryn Masi, Elizabeth Covington, Karen Snyder, Kwang Song, Michael Snyder
We conducted a multi-institutional assessment of a recently developed end-to-end monthly quality assurance (QA) protocol for external beam radiation therapy treatment chains. This protocol validates the entire treatment chain against a baseline to detect the presence of complex errors not easily found in standard component-based QA methods. Participating physicists from 3 institutions ran the end-to-end protocol on treatment chains that include Imaging and Radiation Oncology Core (IROC)-credentialed linacs...
March 20, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/29547397/fixed-object-specific-intensity-compensation-for-cone-beam-optical-ct-radiation-dosimetry
#6
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
https://www.readbyqxmd.com/read/29532785/radiation-characterization-and-dosimetric-measurements-of-a-femto-second-pulsed-laser-ablation-system
#7
Juan Prieto-Pena, Faustino Gomez, Diego M Gonzalez-Castano, Maria Teresa Flores Arias, Justo Arines, Carmen Bao-Varela, Ferran Cambronero-López, Alejandra Martínez Maqueira
Present work describes the radiation quality and dosimetric characterization performed on the micromachining station of the femtosecond STELA (Santiago TErawattLAser) of the University of Santiago de Compostela (Spain). For this aim, ionisation chambers, solid state detectors and radiochromic films were used. The results show the emission of pulsed X-ray produced by laser-accelerated electrons from the ablated material exhibiting both bremsstrahlung and characteristic radiation. Although this radiation was produced unintentionally, a high superficial dose rate can be achieved...
March 13, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29498970/influence-of-backscatter-radiation-on-cranial-bone-fixation-devices
#8
Yoshiaki Sakamoto, Naoyoshi Koike, Hideyuki Takei, Mari Ohno, Naoyuki Shigematsu, Kazuo Kishi
Postoperative radiation can cause ulcer formation, leading to the denudation of skin over alloplastic materials. The influence of backscatter radiation from fixation devices has not been investigated. The aim of this study is to evaluate backscatter dose variations for different cranial bone fixation devices in an experimental model designed to simulate postoperative radiotherapy. The authors assessed the radiation backscatter doses associated with resorbable (PLLA-PGA) and titanium plates. The samples were irradiated with 6 and 10 MV photon beams from a linear accelerator...
March 1, 2018: Journal of Craniofacial Surgery
https://www.readbyqxmd.com/read/29474189/characteristic-of-ebt-xd-and-ebt3-radiochromic-film-dosimetry-for-photon-and-proton-beams
#9
Suphalak Khachonkham, Ralf Dreindl, Gerd Heilemann, Wolfgang Lechner, Hermann Fuchs, Hugo Palmans, Dietmar Georg, Peter Kuess
Recently, a new type of radiochromic film, the EBT XD film, has been introduced for high dose radiotherapy. The EBT XD film contains the same structure as the EBT3 film but has a slightly different composition and a thinner active layer. This study benchmarks the EBT XD against EBT3 film for 6 MV and 10 MV photon beams, as well as for 97.4 MeV and 148.2 MeV proton beams and 15¬ 100 kV x-rays. Dosimetric and film reading characteristics, such as post irradiation darkening, film orientation effect, lateral response artifact (LRA), film sensitivity, energy and beam quality dependency were investigated...
February 23, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29472087/an-assessment-of-a-3d-epid-based-dosimetry-system-using-conventional-two-and-three-dimensional-detectors-for-vmat
#10
S Stevens, P Dvorak, V Spevacek, K Pilarova, M Bray-Parry, J Gesner, A Richmond
PURPOSE: To provide a 3D dosimetric evaluation of a commercial portal dosimetry system using 2D/3D detectors under ideal conditions using VMAT. METHODS: A 2D ion chamber array, radiochromic film and gel dosimeter were utilised to provide a dosimetric evaluation of transit phantom and pre-treatment 'fluence' EPID back-projected dose distributions for a standard VMAT plan. In-house 2D and 3D gamma methods compared pass statistics relative to each dosimeter and TPS dose distributions...
January 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29422538/dose-and-slice-thickness-evaluation-with-nmag-gel-dosimeters-in-computed-tomography
#11
Chun-Chao Chuang, Jay Wu
Computed tomography (CT) has been widely used in clinical diagnosis. It is important to estimate radiation dose and perform image quality assurance procedures for CT scans. In this study, nMAG gel dosimeters were used to simultaneously measure the 300-mm weighted CT dose index (CTDI) and slice sensitivity profile (SSP) for multiple detector CT (MDCT). Magnetic resonance imaging (MRI) was performed on the irradiated gel to create R2‒dose response curves for the tube voltages of 120 and 140 kVp. The gel dosimeters were loaded in three home-made cylindrical phantoms to obtain CTDI100 and CTDI300...
February 8, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29417266/comparison-of-patient-skin-dose-evaluated-using-radiochromic-film-and-dose-calculation-software
#12
Florian Magnier, Maxime Poulin, Claire Van Ngoc Ty, Estelle Osmond, Guillaume Bonniaud, Jeremy Coulot, Bruno Pereira, Louis Boyer, Joel Guersen, Lucie Cassagnes
PURPOSE: To compare, in an interventional radiology setting, peak skin doses (PSDs) delivered as calculated using a dedicated software tool and as measured using radiochromic film. To assess the utility of this dose calculation software tool in routine clinical practice. MATERIALS AND METHODS: First, radiochromic films were positioned on the examination table in the back of an adult anthropomorphic phantom to measure PSD, and X-ray examinations were simulated. Then, films were again positioned in the patient's back for 59 thoracic or abdominopelvic endovascular interventions...
February 7, 2018: Cardiovascular and Interventional Radiology
https://www.readbyqxmd.com/read/29415148/experimental-evaluation-of-dosimetric-characterization-of-gafchromic-ebt3-and-ebt-xd-films-for-clinical-carbon-ion-beams
#13
Shunsuke Yonai, Chinatsu Arai, Kaoru Shimoyama, Nathalie Fournier-Bidoz
Radiochromic film is a very useful tool for 2D dosimetric measurements in radiotherapy because it is self-developing and has very high-spatial resolution. However, considerable care has to be taken in ion beam radiotherapy owing to the quenching effect of high-linear energy transfer (LET) radiation. In this study, the dose responses of GAFchromic EBT3 and EBT-XD films were experimentally investigated using the clinical carbon ion beam at the Heavy Ion Medical Accelerator in Chiba. Results showed that the relations between absorbed dose and net optical density could be expressed well using an equation proposed by Reinhardt (2015)...
February 3, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29399810/absorbed-dose-distributions-from-ophthalmic-106-ru-106-rh-plaques-measured-in-water-with-radiochromic-film
#14
Marcelino Hermida-López, Lorenzo Brualla
PURPOSE: Brachytherapy with106 Ru/106 Rh plaques offers good outcomes for small-to-medium choroidal melanomas and retinoblastomas. The dose measurement of the plaques is challenging, due to the small range of the emitted beta particles and steep dose gradients involved. The scarce publications on film dosimetry of106 Ru/106 Rh plaques used solid phantoms. This work aims to develop a practical method for measuring the absorbed dose distribution in water produced by106 Ru/106 Rh plaques using EBT3 radiochromic film...
February 5, 2018: Medical Physics
https://www.readbyqxmd.com/read/29396087/assessment-of-patient-s-peak-skin-dose-during-abdominopelvic-embolization-using-radiochromic-gafchromic-films
#15
J Greffier, J Goupil, A Larbi, X Stefanovic, F Pereira, G Moliner, S Ovtchinnikoff, J P Beregi, J Frandon
PURPOSE: To assess the value of the routine use of radiochromic films in abdominopelvic embolization procedures to improve patient follow-up. METHODS: A total of 55 patients who underwent transcatheter abdominopelvic embolization were prospectively included. Six types of procedures were evaluated including hepatic chemoembolization (HCE), gonadal veins embolization (GVE), uterine elective embolization (UEE), uterine urgent embolization (UUE), abdominal elective embolization (AEE), and abdominal urgent embolization (AUE)...
January 29, 2018: Diagnostic and Interventional Imaging
https://www.readbyqxmd.com/read/29384730/end-to-end-tests-using-alanine-dosimetry-in-scanned-proton-beams
#16
Antonio Carlino, Clare A Gouldstone, Gabriele Kragl, Erik Traneus, Maurizio Marrale, Stanislav Vatnitsky, Markus Stock, Hugo Palmans
This paper describes end-to-end test procedures as the last fundamental step of medical commissioning before starting clinical operation of the MedAustron synchrotron-based pencil beam scanning (PBS) therapy facility with protons. One in-house homogeneous phantom and two anthropomorphic heterogeneous (head and pelvis) phantoms were used for end-to-end tests at MedAustron. The phantoms were equipped with alanine detectors, radiochromic films and ionization chambers. The correction for the ``quenching'' effect of alanine pellets was implemented in the Monte Carlo platform of the evaluation version of RayStation TPS...
January 31, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29368420/minimizing-dose-variation-from-the-interplay-effect-in-stereotactic-radiation-therapy-using-volumetric-modulated-arc-therapy-for-lung-cancer
#17
Kazuki Kubo, Hajime Monzen, Mikoto Tamura, Makoto Hirata, Kentaro Ishii, Wataru Okada, Ryuta Nakahara, Shun Kishimoto, Ryu Kawamorita, Yasumasa Nishimura
It is important to improve the magnitude of dose variation that is caused by the interplay effect. The aim of this study was to investigate the impact of the number of breaths (NBs) to the dose variation for VMAT-SBRT to lung cancer. Data on respiratory motion and multileaf collimator (MLC) sequence were collected from the cases of 30 patients who underwent radiotherapy with VMAT-SBRT for lung cancer. The NBs in the total irradiation time with VMAT and the maximum craniocaudal amplitude of the target were calculated...
January 25, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29342302/determination-of-the-appropriate-physical-density-of-internal-metallic-ports-in-temporary-tissue-expanders-for-the-treatment-planning-of-post-mastectomy-radiation-therapy
#18
Norifumi Mizuno, Haruna Takahashi, Jiro Kawamori, Naoki Nakamura, Mami Ogita, Shogo Hatanaka, Ryouhei Yamauchi, Masatsugu Hariu, Kenji Sekiguchi
Some patients undergoing breast reconstruction require post-mastectomy radiation therapy, but the metallic ports used in temporary tissue expanders attenuate the X-rays. In this study, we evaluated by the film method, the attenuation of 4 MV and 6 MV X-rays after passing through a metallic port, with the aim of identifying a useful method for determining the appropriate density to use in the radiation treatment planning system (RTPS), taking into account the distance between the metallic port and the targets...
January 12, 2018: Journal of Radiation Research
https://www.readbyqxmd.com/read/29333127/quality-assurance-procedures-based-on-dosimetric-gamma-analysis-as-a-fast-reliable-tool-for-commissioning-brachytherapy-treatment-planning-systems
#19
Grzegorz Zwierzchowski, Grzegorz Bieleda, Janusz Skowronek
Background: Fast and easily repeatable methods for commissioning procedures for brachytherapy (BT) treatment planning systems (TPS) are needed. Radiochromic film dosimetry with gamma analysis is widely used in external beam quality assurance (QA) procedures and planar film dosimetry is also increasingly used for verification of the dose distribution in BT applications. Using the gamma analysis method for comparing calculated and measured dose data could be used for commissioning procedures of the newly developed TG-186 and MBDCA calculation algorithms...
December 2017: Radiology and Oncology
https://www.readbyqxmd.com/read/29290555/-experimental-determination-of-correction-factors-of-four-detectors-used-in-small-field-radiotherapy
#20
L Ben Salem, A Essadok, I Saidani, M Mahdouani, M Benna, K Mahjoubi, M Besbes, F Benna
PURPOSE: The aim of this work is to determine experimentally the correction factors [Formula: see text] for four active commercial dosimeters: two microchambers and two diode detectors based on the output factor measured with radiochromic film for a radiotherapy linear accelerator equipped with circular cones. MATERIALS AND METHODS: Initially, a radiochromic film dosimetry measurement protocol with an accuracy of 2% was developed to approach the "reference output factor"...
February 2018: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
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