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Gafchromic film

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https://www.readbyqxmd.com/read/28325019/frameless-stereotactic-radiosurgery-fsrs-end-to-end-test-with-ebt-xd-gafchromic-film
#1
Yulin Song, Ceferino Obcemea, Boris Mueller, Borys Mychalczak
Frame-based stereotactic radiosurgery (SRS) has been widely used to treat functional disorders, vascular lesions, and primary benign and malignant tumors. Recently, SRS is being increasingly used to treat solitary brain metastases. However, due to its highly invasive nature, frame-based SRS is being gradually replaced by frameless SRS (fSRS). fSRS aims at improving patient comfort and achieving stable patient immobilization with non-invasive means and accurate target localization with image guidance technique...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28303745/grid-therapy-using-high-definition-multileaf-collimators-realizing-benefits-of-the-bystander-effect
#2
Valery Peng, Natalka Suchowerska, Linda Rogers, Elizabeth Claridge Mackonis, Samantha Oakes, David R McKenzie
BACKGROUND: In microbeam radiotherapy (MRT), parallel arrays of high-intensity synchrotron x-ray beams achieve normal tissue sparing without compromising tumor control. Grid-therapy using clinical linacs has spatial modulation on a larger scale and achieves promising results for palliative treatments of bulky tumors. The availability of high definition multileaf collimators (HDMLCs) with 2.5 mm leaves provides an opportunity for grid-therapy to more closely approach MRT. However, challenges to the wider implementation of grid-therapy remain because spatial modulation of the target volume runs counter to current radiotherapy practice and mechanisms for the beneficial effects of MRT are not fully understood...
March 17, 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28300373/sum-signal-dosimetry-a-new-approach-for-high-dose-quality-assurance-with-gafchromic-ebt3
#3
Davide Cusumano, Maria Luisa Fumagalli, Francesco Ghielmetti, Linda Rossi, Giuliano Grossi, Raffaella Lanzarotti, Laura Fariselli, Elena De Martin
Gafchromic EBT3 film dosimetry in radiosurgery (RS) and hypofractionated radiotherapy (HRT) is complicated by the limited film accuracy at high fractional doses. The aim of this study is to develop and evaluate sum signal (SS) film dosimetry to increase dose resolution at high fractional doses, thus allowing for use of EBT3 for dose distribution verification of RS/HRT treatments. To characterize EBT3 dose-response, a calibration was performed in the dose range 0.44-26.43 Gy. Red (RC) and green (GC) channel net optical densities were linearly added to produce the SS...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297418/characterization-of-a-2-5-mv-inline-portal-imaging-beam
#4
James L Gräfe, Jennifer Owen, J Eduardo Villarreal-Barajas, Rao F H Khan
A new megavoltage (MV) energy was recently introduced on Varian TrueBeam linear accelerators for imaging applications. This work describes the experimental characterization of a 2.5 MV inline portal imaging beam for commissioning, routine clinical use, and quality assurance purposes. The beam quality of the 2.5 MV beam was determined by measuring a percent depth dose, PDD, in water phantom for 10×10 cm2 field at source-to-surface distance 100 cm with a CC13 ion chamber, plane parallel Markus chamber, and GafChromic EBT3 film...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297357/correction-of-nonuniformity-error-of-gafchromic-ebt2-and-ebt3
#5
Toshizo Katsuda, Rumi Gotanda, Tatsuhiro Gotanda, Takuya Akagawa, Nobuyoshi Tanki, Tadao Kuwano, Kouichi Yabunaka
This study investigates an X-ray dose measurement method for computed tomography using Gafchromic films. Nonuniformity of the active layer is a major problem in Gafchromic films. In radiotherapy, nonuniformity error is reduced by applying the double-exposure technique, but this is impractical in diagnostic radiology because of the heel effect. Therefore, we propose replacing the X-rays in the double-exposure technique with ultraviolet (UV)-A irradiation of Gafchromic EBT2 and EBT3. To improve the reproducibility of the scan position, Gafchromic EBT2 and EBT3 films were attached to a 3-mm-thick acrylic plate...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297335/on-the-accuracy-of-dose-prediction-near-metal-fixation-devices-for-spine-sbrt
#6
Zhangkai J Cheng, Regina M Bromley, Brad Oborn, Martin Carolan, Jeremy T Booth
The metallic fixations used in surgical procedures to support the spine mechanically usually consist of high-density materials. Radiation therapy to palliate spinal cord compression can include prophylactic inclusion of potential tumor around the site of such fixation devices. Determination of the correct density and shape of the spine fixation device has a direct effect on the dose calculation of the radiation field. Even with the application of modern computed tomography (CT), under- or overestimation of dose, both immediately next to the device and in the surrounding tissues, can occur due to inaccuracies in the dose prediction algorithm...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297311/treatment-planning-for-metals-using-an-extended-ct-number-scale
#7
John P Mullins, Michael P Grams, Michael G Herman, Debra H Brinkmann, John A Antolak
Metal implants which saturate the CT number scale may require dosimetrist and physicist involvement to manually contour and assign an appropriate value to the metal for accurate dose calculation. This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high-Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297303/experimental-evaluation-of-a-gpu-based-monte-carlo-dose-calculation-algorithm-in-the-monaco-treatment-planning-system
#8
Moti R Paudel, Anthony Kim, Arman Sarfehnia, Sayed B Ahmad, David J Beachey, Arjun Sahgal, Brian M Keller
A new GPU-based Monte Carlo dose calculation algorithm (GPUMCD), developed by the vendor Elekta for the Monaco treatment planning system (TPS), is capable of modeling dose for both a standard linear accelerator and an Elekta MRI linear accelerator. We have experimentally evaluated this algorithm for a standard Elekta Agility linear accelerator. A beam model was developed in the Monaco TPS (research version 5.09.06) using the commissioned beam data for a 6 MV Agility linac. A heterogeneous phantom representing several scenarios - tumor-in-lung, lung, and bone-in-tissue - was designed and built...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297290/gafchromic-ebt-xd-film-dosimetry-characterization-in-high-dose-volumetric-modulated-arc-therapy
#9
Hideharu Miura, Shuichi Ozawa, Fumika Hosono, Naoki Sumida, Toshiya Okazue, Kiyoshi Yamada, Yasushi Nagata
Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT-XD films have been designed for optimal performance in the 40-4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose-response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high-dose volumetric-modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0-4,000 cGy range...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297286/the-dose-penumbra-of-a-custom-made-shield-used-in-hemibody-skin-electron-irradiation
#10
Charlotte I Rivers, Ismail AlDahlawi, Iris Z Wang, Anurag K Singh, Matthew B Podgorsak
We report our technique for hemibody skin electron irradiation with a custom-made plywood shield. The technique is similar to our clinical total skin electron irradiation (TSEI), performed with a six-pair dual field (Stanford technique) at an extended source-to-skin distance (SSD) of 377 cm, with the addition of a plywood shield placed at 50 cm from the patient. The shield is made of three layers of standard 5/8" thick plywood (total thickness of 4.75 cm) that are clamped securely on an adjustable-height stand...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297285/deriving-detector-specific-correction-factors-for-rectangular-small-fields-using-a-scintillator-detector
#11
Yujiao Qin, Hualiang Zhong, Ning Wen, Karen Snyder, Yimei Huang, Indrin J Chetty
The goal of this study was to investigate small field output factors (OFs) for flattening filter-free (FFF) beams on a dedicated stereotactic linear accelerator-based system. From this data, the collimator exchange effect was quantified, and detector-specific correction factors were generated. Output factors for 16 jaw-collimated small fields (from 0.5 to 2 cm) were measured using five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1)...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296313/determination-of-mlc-model-parameters-for-monaco-using-commercial-diode-arrays
#12
Paul Kinsella, Laura Shields, Patrick McCavana, Brendan McClean, Brian Langan
Multileaf collimators (MLCs) need to be characterized accurately in treatment planning systems to facilitate accurate intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). The aim of this study was to examine the use of MapCHECK 2 and ArcCHECK diode arrays for optimizing MLC parameters in Monaco X-ray voxel Monte Carlo (XVMC) dose calculation algorithm. A series of radiation test beams designed to evaluate MLC model parameters were delivered to MapCHECK 2, ArcCHECK, and EBT3 Gafchromic film for comparison...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28273357/energy-and-field-size-dependence-of-a-silicon-diode-designed-for-small-field-dosimetry
#13
Mehran Yarahmadi, Sonja Wegener, Otto A Sauer
PURPOSE: To investigate the energy dependence/spectral sensitivity of silicon diodes designed for small-field dosimetry and obtain response factors (RFs) for arbitrary photon spectra using Monte Carlo (MC) simulations. METHODS: The EGSnrc user-code DOSRZnrc was used to calculate the dose deposition in water and in the active volume of a stereotactic diode field detector (SFD). Then the RFs of the SFD were calculated for several circular field sizes and energies at 5 cm depth in water...
March 8, 2017: Medical Physics
https://www.readbyqxmd.com/read/28212708/development-and-performance-evaluation-of-a-three-dimensional-clinostat-synchronized-heavy-ion-irradiation-system
#14
Hiroko Ikeda, Hikaru Souda, Anggraeini Puspitasari, Kathryn D Held, Jun Hidema, Takeshi Nikawa, Yukari Yoshida, Tatsuaki Kanai, Akihisa Takahashi
Outer space is an environment characterized by microgravity and space radiation, including high-energy charged particles. Astronauts are constantly exposed to both microgravity and radiation during long-term stays in space. However, many aspects of the biological effects of combined microgravity and space radiation remain unclear. We developed a new three-dimensional (3D) clinostat synchronized heavy-ion irradiation system for use in ground-based studies of the combined exposures. Our new system uses a particle accelerator and a respiratory gating system from heavy-ion radiotherapy to irradiate samples being rotated in the 3D clinostat with carbon-ion beams only when the samples are in the horizontal position...
February 2017: Life Sciences in Space Research
https://www.readbyqxmd.com/read/28196271/dose-distribution-at-the-bragg-peak-dose-measurements-using-ebt-and-rtqa-gafchromic-film-set-at-two-positions-to-the-central-beam-axis
#15
Dorota Maria Borowicz, Julian Malicki, Gennady Mytsin, Konstantin Shipulin
AIM: To evaluate the impact of radiochromic film positioning relative to the central beam axis (CAX) in proton beam therapy. Secondarily, to compare the dosimetric measurements obtained by RTQA and EBT film and to compare these to the doses calculated by the treatment planning system (TPS). METHODS: EBT and RTQA dosimetric radiochromic films were immersed in a water phantom and irradiated with a proton beam. The films were placed parallel to the CAX and at a 5º angle on the horizontal plane to assess the effect of film inclination on Bragg peak profiles...
February 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/28144120/simplified-method-for-creating-a-density-absorbed-dose-calibration-curve-for-the-low-dose-range-from-gafchromic-ebt3-film
#16
Tatsuhiro Gotanda, Toshizo Katsuda, Rumi Gotanda, Tadao Kuwano, Takuya Akagawa, Nobuyoshi Tanki, Akihiko Tabuchi, Tetsunori Shimono, Yasuyuki Kawaji
Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method...
October 2016: Journal of Medical Physics
https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#17
Sara Gholampourkashi, Miro Vujicic, Jason Belec, Joanna E Cygler, Emily Heath
PURPOSE: To evaluate a novel 4D Monte Carlo simulation tool by comparing calculations to physical measurements using a respiratory motion phantom. METHODS: We used a dynamic Quasar phantom in both stationary and breathing states (sinusoidal motion of amplitude of 1.8 cm and period of 3.3 s) for dose measurements on an Elekta Agility linear accelerator. Gafchromic EBT3 film and the RADPOS 4D dosimetry system were placed inside the lung insert of the phantom to measure dose profiles and point-dose values at the center of the spherical tumor inside the insert...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102944/a-simple-and-robust-trajectory-based-stereotactic-radiosurgery-treatment
#18
Byron Wilson, Karl Otto, Ermias Gete
INTRODUCTION: We present a Trajectory-based Volumetric Modulated Arc Therapy (TVMAT) technique for Stereotactic Radiosurgery (SRS) that takes advantage of a modern linacs ability to modulate dose rate and move the couch dynamically. In addition, we investigate the quality of the developed TVMAT method and the dosimetric accuracy of the technique. METHODS: The main feature of the TVMAT technique is a standard beam trajectory formed by dynamic motion of the treatment couch and the linac gantry...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28094853/high-dose-per-pulse-electron-beam-dosimetry-a-model-to-correct-for-the-ion-recombination-in-the-advanced-markus-ionization-chamber
#19
Kristoffer Petersson, Maud Jaccard, Jean-François Germond, Thierry Buchillier, François Bochud, Jean Bourhis, Marie-Catherine Vozenin, Claude Bailat
PURPOSE: The purpose of this work was to establish an empirical model of the ion recombination in the Advanced Markus ionization chamber for measurements in high dose rate/dose-per-pulse electron beams. In addition, we compared the observed ion recombination to calculations using the standard Boag two-voltage-analysis method, the more general theoretical Boag models, and the semiempirical general equation presented by Burns and McEwen. METHODS: Two independent methods were used to investigate the ion recombination: (a) Varying the grid tension of the linear accelerator (linac) gun (controls the linac output) and measuring the relative effect the grid tension has on the chamber response at different source-to-surface distances (SSD)...
January 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28048877/su-g-brb-08-investigation-on-the-magnetic-field-effect-on-tlds-oslds-and-gafchromic-films-using-an-mr-linac
#20
Z Wen, J Wang, W Jiang, D O'Brien, G Sawakuchi, G Ibbott
PURPOSE: To investigate whether a strong magnetic field (B=1.5 T) can affect dose responses of thermoluminescent dosimeters (TLDs), optically stimulated luminescence dosimeters (OSLDs) and Gafchromic films using an MR-Linac (Elekta) before and after the magnet was ramped down from 1.5 T to 0 T. METHODS: Three types of dosimeters (TLDs, OSLDs, EBT3 films) were divided into two groups. Group 1 was first irradiated in a phantom of Solid Water slabs (Standard Imaging) inside a B=1...
June 2016: Medical Physics
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