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https://www.readbyqxmd.com/read/29422538/dose-and-slice-thickness-evaluation-with-nmag-gel-dosimeters-in-computed-tomography
#1
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
#2
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
#3
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-106ru-106-1-rh-plaques-measured-in-water-with-radiochromic-film
#4
M Hermida-López, L Brualla
PURPOSE: Brachytherapy with 106 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 of 106 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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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"...
December 28, 2017: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
https://www.readbyqxmd.com/read/29282134/small-field-dosimetry-for-the-small-animal-radiotherapy-research-platform-sarrp
#11
Mihaela Ghita, Stephen J McMahon, Hannah F Thompson, Conor K McGarry, Raymond King, Sarah O S Osman, Jonathan L Kane, Amanda Tulk, Giuseppe Schettino, Karl T Butterworth, Alan R Hounsell, Kevin M Prise
BACKGROUND: Preclinical radiation biology has become increasingly sophisticated due to the implementation of advanced small animal image guided radiation platforms into laboratory investigation. These small animal radiotherapy devices enable state-of-the-art image guided therapy (IGRT) research to be performed by combining high-resolution cone beam computed tomography (CBCT) imaging with an isocentric irradiation system. Such platforms are capable of replicating modern clinical systems similar to those that integrate a linear accelerator with on-board CBCT image guidance...
December 28, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/29204169/independent-assessment-of-source-position-for-gynecological-applicator-in-high-dose-rate-brachytherapy
#12
Hiroyuki Okamoto, Satoshi Nakamura, Shie Nishioka, Kotaro Iijima, Akihisa Wakita, Yukinao Abe, Naoki Tohyama, Shinji Kawamura, Toshiyuki Minemura, Jun Itami
Purpose: The aim of this study is to describe a phantom designed for independent examination of a source position in brachytherapy that is suitable for inclusion in an external auditing program. Material and methods: We developed a phantom that has a special design and a simple mechanism, capable of firmly fixing a radiochromic film and tandem-ovoid applicators to assess discrepancies in source positions between the measurements and treatment planning system (TPS)...
October 2017: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/29176074/validation-and-uncertainty-analysis-of-a-pre-treatment-2d-dose-prediction-model
#13
Jose A Baeza, Cecile J A Wolfs, Sebastiaan M J J G Nijsten, Frank Verhaegen
Independent verification of complex treatment delivery with megavolt photon beam radiotherapy (RT) has been effectively used to detect and prevent errors. This work presents the validation and uncertainty analysis of a model that predicts 2D portal dose images without a patient or phantom in the beam. The prediction model is based on an exponential point dose model with separable primary and secondary photon fluence components. The model includes a scatter kernel, off-axis ratio map, transmission values and penumbra kernels for beam-delimiting components...
November 26, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29173922/on-the-re-calibration-process-in-radiochromic-film-dosimetry
#14
Carmen Ruiz-Morales, Juan Antonio Vera-Sánchez, Antonio González-López
PURPOSE: The accuracy and precision of the dose estimates obtained with radiochromic film dosimetry are investigated in a clinical environment. The improvement in the accuracy of dose estimates reached with corrective methods is analyzed. Two novel re-calibration algorithms for radiochromic film dosimetry are presented. METHODS: Two different EBT3 lots are evaluated in two different centres. They are calibrated in Varian linacs and read in two different EPSON scaners...
October 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29173920/evaluation-and-clinical-implementation-of-in-vivo-dosimetry-for-kv-radiotherapy-using-radiochromic-film-and-micro-silica-bead-thermoluminescent-detectors
#15
Antony L Palmer, Shakardokht M Jafari, Ioanna Mone, Sarah Muscat
PURPOSE: kV radiotherapy treatment calculations are based on flat, homogenous, full-scatter reference conditions. However, clinical treatments often include surface irregularities and inhomogeneities, causing uncertainty. Therefore, confirmation of actual delivered doses in vivo is valuable. The current study evaluates, and implements, radiochromic film and micro silica bead TLD for in vivo kV dosimetry. METHODS: The kV energy and dose response of EBT3 film and silica bead TLD was established and uncertainty budgets determined...
October 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29164628/technical-note-response-time-evolution-of-xr-qa2-gafchromic-tm-film-models
#16
Saad Aldelaijan, Nada Tomic, Pavlos Papaconstadopoulos, James Schneider, Jan Seuntjens, Shelley Shih, David Lewis, Slobodan Devic
PURPOSE: To evaluate the response of the newest XR-QA2 GafChromic(™) film model in terms of post-exposure signal growth and energy response in comparison with the older XR-QA (Version 2) model. METHODS: Pieces of film were irradiated to air kerma in air values up to 12 cGy with several beam qualities (5.3-8.25 mm Al) commonly used for CT scanning. Film response was scored in terms of net reflectance from scanned film images at various points in time post-irradiation ranging from 1 to 7 days and 5 months post exposure...
November 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/29159807/experimental-investigation-of-gafchromic-%C3%A2-ebt3-intrinsic-energy-dependence-with-kilovoltage-x-rays-137-cs-and-60-co
#17
Cliff G Hammer, Benjamin Saul Rosen, Jessica M Fagerstrom, Wesley S Culberson, Larry A DeWerd
PURPOSE: To determine experimentally the intrinsic energy response, kbq , of EBT3 GafChromic(®) radiochromic film with kilovoltage x-rays,(137) Cs, and (60) Co in therapeutic and diagnostic dose ranges through direct measurement with an accompanying mathematical approach to describe the physical processes involved. METHODS: EBT3 film was irradiated to known doses using (60) Co, (137) Cs, and 13 NIST-matched kilovoltage x-ray beams. Seven dose levels, ranging from 57 to 7002 mGy, were chosen for this work...
November 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/29155691/magnetic-fields-are-causing-small-but-significant-changes-of-the-radiochromic-ebt3-film-response-to-6-mv-photons
#18
Bjoern Delfs, Andreas Alexander Schoenfeld, Daniela Poppinga, Ralf-Peter Kapsch, Ping Jiang, Dietrich Harder, Bjoern Poppe, Hui Khee Looe
The optical density (OD) of EBT3 radiochromic exposed to absorbed doses to water up to D = 20 Gy in magnetic fields of B = 0.35 and 1.42 T was measured in three colour channels. A 7 cm wide water phantom with fixed film holder was placed in magnetic fields and was irradiated by a 6 MV photon beam whose axis was directed at right angles with the field lines. The doses at the film position at water depth 5 cm were measured with a calibrated ionization chamber when the magnet was switched off and were converted to the doses in presence of the magnetic field via the monitor units and by a Monte Carlo-calculated correction accounting for the slight change of the depth dose curves in magnetic fields...
November 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29125832/minibeam-radiotherapy-with-small-animal-irradiators-in-vitro-and-in-vivo-feasibility-studies
#19
Soha Bazyar, Christina R Inscoe, E Timothy O'Brian, Otto Zhou, Yueh Z Lee
Minibeam radiation therapy (MBRT) delivers an ultrahigh dose of x-ray (⩾100 Gy) in 200-1000 µm beams (peaks), separated by wider non-irradiated regions (valleys) usually as a single temporal fraction. Preclinical studies performed at synchrotron facilities revealed that MBRT is able to ablate tumors while maintaining normal tissue integrity. The main purpose of the present study was to develop an efficient and accessible method to perform MBRT using a conventional x-ray irradiator. We then tested this new method both in vitro and in vivo...
November 10, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29102741/physics-aspects-of-the-papillon-technique-five-decades-later
#20
Li Heng Liang, Nada Tomic, Te Vuong, Saad Aldelaijan, Hamed Bekerat, Francois DeBlois, Jan Seuntjens, Slobodan Devic
PURPOSE: The Papillon technique using 50-kVp soft X-rays to treat rectal adenocarcinomas was developed and clinically implemented in the 1960s. We describe differences between accurate dosimetry and clinical implementation of this technique that is extending from its very inception to date. METHODS AND MATERIALS: A renaissance of the Papillon technique occurred with two recently introduced 50-kVp systems: Papillon+ by Ariane and a custom-made rectal applicator (consisting of a surface applicator inserted into a proctoscope) by iCAD's Xoft Axxent Electronic Brachytherapy (eBT) System (iCad, Inc...
November 1, 2017: Brachytherapy
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