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MV and KV dose

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https://www.readbyqxmd.com/read/28644819/quantifying-the-accuracy-and-precision-of-a-novel-real-time-6-degree-of-freedom-kilovoltage-intrafraction-monitoring-kim-target-tracking-system
#1
J-H Kim, D T Nguyen, C-Y Huang, T Fuangrod, V Caillet, R O'Brien, P Poulsen, J Booth, P Keall
Target rotation can considerably impact the delivered radiotherapy dose depending on the tumour shape. More accurate tumour pose during radiotherapy treatment can be acquired through tracking in 6 degrees-of-freedom (6 DoF) rather than in translation only. A novel real-time 6 DoF kilovoltage intrafraction monitoring (KIM) target tracking system has recently been developed. In this study, we experimentally evaluated the accuracy and precision of the 6 DoF KIM implementation. Real-time 6 DoF KIM motion measurements were compared against the ground truth motion retrospectively derived from kV/MV triangulation for a range of lung and prostate tumour motion trajectories as well as for various static poses using a phantom...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28490985/imaged-guided-liver-stereotactic-body-radiotherapy-using-vmat-and-real-time-adaptive-tumor-gating-concerns-about-technique-and-preliminary-clinical-results
#2
Carmen Llacer-Moscardo, Olivier Riou, David Azria, Ludovic Bedos, Norbert Ailleres, Francois Quenet, Philippe Rouanet, Marc Ychou, Pascal Fenoglietto
BACKGROUND: Motion management is a major challenge in abdominal SBRT. We present our study of SBRT for liver tumors using intrafraction motion review (IMR) allowing simultaneous KV information and MV delivery to synchronize the beam during gated RapidArc treatment. MATERIALS AND METHODS: Between May 2012 and March 2015, 41 patients were treated by liver SBRT using gated RapidArc technique in a Varian Novalis Truebeam STx linear accelerator. PTV was created by expanding 5 mm from the ITV...
March 2017: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/28449625/clinical-study-of-orthogonal-view-phase-matched-digital-tomosynthesis-for-lung-tumor-localization
#3
You Zhang, Lei Ren, Irina Vergalasova, Fang-Fang Yin
BACKGROUND AND PURPOSE: Compared to cone-beam computed tomography, digital tomosynthesis imaging has the benefits of shorter scanning time, less imaging dose, and better mechanical clearance for tumor localization in radiation therapy. However, for lung tumors, the localization accuracy of the conventional digital tomosynthesis technique is affected by the lack of depth information and the existence of lung tumor motion. This study investigates the clinical feasibility of using an orthogonal-view phase-matched digital tomosynthesis technique to improve the accuracy of lung tumor localization...
January 1, 2017: Technology in Cancer Research & Treatment
https://www.readbyqxmd.com/read/28428474/evaluation-of-absorbed-dose-for-cbct-in-image-guided-radiation-therapy-comparison-of-each-devices-and-facilities
#4
Yumiko Kitazato, Noriyuki Kuga, Katsutoshi Shirieda, Masahiro Enzaki, Yuji Nakaguchi, Yoshinobu Shimohigashi, Toshihisa Kawasaki, Masahiko Toyoda, Daisuke Kawahara, Fujio Araki, Shinji Kawamura
Recently, intensity-modulated radiation therapy (IMRT) is used worldwide, highly accurate verification of the location using image-guided radiation therapy (IGRT) has become critical. However, the use of cone-beam computed tomography (CBCT) to ascertain the location each time raises concerns about its influence on radiotherapy dosage and increased radiation exposure. The purpose of this study was to measure the absorbed dose using nine kilovoltage (kV) devices and two megavoltage (MV) devices (total 11 devices) at eight facilities, compare the absorbed dose among the devices, and assess the characteristics of the respective devices to ensure optimal clinical operation...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28425222/class-iii-antiarrhythmic-drugs-amiodarone-and-dronedarone-impair-kir-2-1-backward-trafficking
#5
Yuan Ji, Hiroki Takanari, Muge Qile, Lukas Nalos, Marien J C Houtman, Fee L Romunde, Raimond Heukers, Paul M P van Bergen En Henegouwen, Marc A Vos, Marcel A G van der Heyden
Drug-induced ion channel trafficking disturbance can cause cardiac arrhythmias. The subcellular level at which drugs interfere in trafficking pathways is largely unknown. KIR 2.1 inward rectifier channels, largely responsible for the cardiac inward rectifier current (IK1 ), are degraded in lysosomes. Amiodarone and dronedarone are class III antiarrhythmics. Chronic use of amiodarone, and to a lesser extent dronedarone, causes serious adverse effects to several organs and tissue types, including the heart. Both drugs have been described to interfere in the late-endosome/lysosome system...
April 19, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28338470/reducing-scan-angle-using-adaptive-prior-knowledge-for-a-limited-angle-intrafraction-verification-live-system-for-conformal-arc-radiotherapy
#6
Yawei Zhang, Fang-Fang Yin, You Zhang, Lei Ren
The purpose of this study is to develop an adaptive prior knowledge guided image estimation technique to reduce the scan angle needed in the limited-angle intrafraction verification (LIVE) system for 4D-CBCT reconstruction. The LIVE system has been previously developed to reconstruct 4D volumetric images on-the-fly during arc treatment for intrafraction target verification and dose calculation. In this study, we developed an adaptive constrained free-form deformation reconstruction technique in LIVE to further reduce the scanning angle needed to reconstruct the 4D-CBCT images for faster intrafraction verification...
May 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28298966/radiation-dose-enhancement-in-skin-therapy-with-nanoparticle-addition-a-monte-carlo-study-on-kilovoltage-photon-and-megavoltage-electron-beams
#7
Xiao J Zheng, James C L Chow
AIM: To investigated the dose enhancement due to the incorporation of nanoparticles in skin therapy using the kilovoltage (kV) photon and megavoltage (MV) electron beams. Monte Carlo simulations were used to predict the dose enhancement when different types and concentrations of nanoparticles were added to skin target layers of varying thickness. METHODS: Clinical kV photon beams (105 and 220 kVp) and MV electron beams (4 and 6 MeV), produced by a Gulmay D3225 orthovoltage unit and a Varian 21 EX linear accelerator, were simulated using the EGSnrc Monte Carlo code...
February 28, 2017: World Journal of Radiology
https://www.readbyqxmd.com/read/28296309/characterization-and-evaluation-of-2-5-mv-electronic-portal-imaging-for-accurate-localization-of-intra-and-extracranial-stereotactic-radiosurgery
#8
Kwang Hyun Song, Karen Chin Snyder, Jinkoo Kim, Haisen Li, Wen Ning, Robert Rusnac, Paul Jackson, James Gordon, Salim M Siddiqui, Indrin J Chetty
2.5 MV electronic portal imaging, available on Varian TrueBeam machines, was characterized using various phantoms in this study. Its low-contrast detectability, spatial resolution, and contrast-to-noise ratio (CNR) were compared with those of conventional 6 MV and kV planar imaging. Scatter effect in large patient body was simulated by adding solid water slabs along the beam path. The 2.5 MV imaging mode was also evaluated using clinically acquired images from 24 patients for the sites of brain, head and neck, lung, and abdomen...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28263949/comparison-of-2d-and-3d-modeled-tumor-motion-estimation-prediction-for-dynamic-tumor-tracking-during-arc-radiotherapy
#9
Wu Liu, Xiangyu Ma, Huagang Yan, Zhe Chen, Ravinder Nath, Haiyun Li
Many real-time imaging techniques have been developed to localize a target in 3D space or in a 2D beam's eye view (BEV) plane for intrafraction motion tracking in radiation therapy. With tracking system latency, the 3D-modeled method is expected to be more accurate even in terms of 2D BEV tracking error. No quantitative analysis, however, has been reported. In this study, we simulated co-planar arc deliveries using respiratory motion data acquired from 42 patients to quantitatively compare the accuracy between 2D BEV and 3D-modeled tracking in arc therapy and to determine whether 3D information is needed for motion tracking...
March 6, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28211070/use-of-proximal-operator-graph-solver-for-radiation-therapy-inverse-treatment-planning
#10
Xinmin Liu, Charles Pelizzari, Andrew H Belcher, Zachary Grelewicz, Rodney D Wiersma
PURPOSE: Most radiation therapy optimization problems can be formulated as an unconstrained problem and solved efficiently by quasi-Newton methods such as the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. However, several next generation planning techniques such as total variation regularization- based optimization and MV+kV optimization, involve constrained or mixed-norm optimization, and cannot be solved by quasi-Newton methods. Using standard optimization algorithms on such problems often leads to prohibitively long optimization times and large memory requirements...
April 2017: Medical Physics
https://www.readbyqxmd.com/read/28133751/feasibility-of-external-beam-radiation-therapy-to-deep-seated-targets-with-kilovoltage-x-rays
#11
Magdalena Bazalova-Carter, Michael D Weil, Dylan Yamabe Breitkreutz, Brian P Wilfley, Edward E Graves
PURPOSE: Radiation therapy to deep-seated targets is typically delivered with megavoltage x-ray beams generated by medical linear accelerators or (60) Co sources. Here, we used computer simulations to design and optimize a lower energy kilovoltage x-ray source generating acceptable dose distributions to a deep-seated target. METHODS: The kilovoltage arc therapy (KVAT) x-ray source was designed to treat a 4-cm diameter target located at a 10-cm depth in a 40-cm diameter homogeneous cylindrical phantom...
February 2017: Medical Physics
https://www.readbyqxmd.com/read/28133744/current-modulated-volume-of-interest-imaging-for-kilovoltage-intrafaction-monitoring-of-the-prostate
#12
David Parsons, M Tynan R Stevens, James L Robar
PURPOSE: The focus of this work was to improve the available kV image quality for continuous intrafraction monitoring of the prostate during volumetric modulated arc therapy. This is investigated using a novel blade collimation system enabling tube current modulated (TCM) volume-of-interest (VOI) imaging of prostate fiducial markers during radiotherapy, and Monte Carlo simulation of MV scatter. MATERIALS AND METHODS: A four-blade dynamic kV collimator was used to track a VOI containing gold fiducial markers embedded in a dynamic pelvis phantom during gantry rotation...
April 2017: Medical Physics
https://www.readbyqxmd.com/read/28069053/influence-of-daily-imaging-on-plan-quality-and-normal-tissue-toxicity-for-prostate-cancer-radiotherapy
#13
Katharina Bell, Marina Heitfeld, Norbert Licht, Christian Rübe, Yvonne Dzierma
BACKGROUND: Modern radiotherapy offers various possibilities for image guided verification of patient positioning. Different clinically relevant IGRT (image guided radiotherapy) scenarios were considered with regard to their influence on dosimetric plan quality and normal tissue complication probability (NTCP). METHODS: This study is based on treatment plans of 50 prostate patients. We evaluate the clinically performed IGRT and simulate the influence of different daily IGRT scenarios on plan quality...
January 10, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28048828/su-g-bra-09-estimation-of-motion-tracking-uncertainty-for-real-time-adaptive-imaging
#14
H Yan, Z Chen, R Nath, W Liu
PURPOSE: kV fluoroscopic imaging combined with MV treatment beam imaging has been investigated for intrafractional motion monitoring and correction. It is, however, subject to additional kV imaging dose to normal tissue. To balance tracking accuracy and imaging dose, we previously proposed an adaptive imaging strategy to dynamically decide future imaging type and moments based on motion tracking uncertainty. kV imaging may be used continuously for maximal accuracy or only when the position uncertainty (probability of out of threshold) is high if a preset imaging dose limit is considered...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048750/su-f-j-26-performance-of-2-5mv-portal-imaging-in-comparison-with-kv-x-ray-and-6mv-and-flattening-filter-free-6mv-portal-imaging
#15
J Duan, Y Yang, A Faught, E Subashi, Q Wu, F Yin
PURPOSE: To assess image quality and imaging dose of 2.5MV electronic portal imaging in comparison to kV imaging and 6MV and Flattening-Filter-Free 6MV (6MVFFF) portal imaging using a DMI imager. METHODS: Quantitative assessment of image quality was performed with Leeds and Las Vegas test phantoms in conjunction with qualitative evaluation of clinical patient images for kV imaging and 2.5MV, 6MV and 6MVFFF portal imaging. High and low contrast resolutions were evaluated and imaging doses were measured using these x-rays...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048732/su-f-j-15-the-use-of-cbct-for-dose-calculations-in-h-n-patients-impact-of-limited-fov
#16
B Rosen, C Lee, K Brock
PURPOSE: To investigate the impact of limited superior and inferior (SI) field-of-view (FOV) associated with on-board kV CBCT images for dose calculation. METHODS: First, a (10×10) cm(2) continuous arc 6 MV treatment plan was calculated for fourteen virtual water phantoms of varying SI thicknesses (5 to 15 cm) to replicate the FOV effect. In addition, 70 Gy VMAT plans from two H/N patients were calculated on their corresponding planning CT (pCT) and first fraction CBCT image volumes...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048660/tu-b-201-01-an-overview-of-tg-180
#17
G Ding
Radiotherapy is in the era of image guided radiation therapy (IGRT) in which imaging procedures are routinely performed for patient positioning, and target localization. The additional imaging dose delivered may increase risk to the patient and therefore needs to be managed. This lecture provides an overview of the AAPM TG-180 which is charged with: providing an overview on imaging dose including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT) as well as providing general guidelines for commissioning and managing imaging dose calculations...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048549/th-a-204-01-part-i-key-data-for-ionizing-radiation-dosimetry
#18
S Seltzer
The ICRU is currently finalizing a report on key data for radiation dosimetry. This multi-year review has resulted in a number of recommendations regarding "fundamental" data that are used in dosimetry related to radiation therapy. This educational session will explain the background for the ICRU committee's work, the content and conclusions of the report and the impact on outputs, including NIST primary standards, ADCL calibration coefficients and clinical reference dosimetry. Parameters and beam modalities potentially affected by this report include: The mean excitation energy, I, for graphite, air, and water, The average energy required to create an ion pair in dry air (commonly referred to as W/e), The uncertainty in the determination of air kerma in kV x-rays The absolute value of Co-60 and Cs-137 primary standards and the dissemination of calibration coefficients, The determination of air kerma strength for Ir-192 HDR brachytherapy sources Ion chamber kQ factors for linac MV beams Ion chamber kQ factors for proton beams...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048393/su-f-t-529-dosimetric-investigation-of-a-rotating-gamma-ray-system-for-imagedguided-modulated-arc-radiotherapy
#19
C Ma, O Chibani, A Eldib, J Li, L Chen
PURPOSE: Because of their effectiveness and efficiency, rotational arc radiotherapy (MAT) techniques have been developed on both specialty machines such as Tomotherapy and conventional linear accelerators. This work investigates a new rotating Gamma therapy system for image guided MAT and SBRT of intra/extracranial tumors. METHODS: The CyberMAT system (Cyber Medical Corp., China) consists of a ring gantry with a gamma source (effective source size 1cm and 1.7cm respectively), a 120-leaf MLC, a kV CBCT and an EPID...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048308/we-de-bra-01-science-council-junior-investigator-competition-winner-acceleration-of-a-limited-angle-intrafraction-verification-live-system-using-adaptive-prior-knowledge-based-image-estimation
#20
Y Zhang, F Yin, Y Zhang, L Ren
PURPOSE: To develop an adaptive prior knowledge based image estimation method to reduce the scan angle needed in the LIVE system to reconstruct 4D-CBCT for intrafraction verification. METHODS: The LIVE system has been previously proposed to reconstructs 4D volumetric images on-the-fly during arc treatment for intrafraction target verification and dose calculation. This system uses limited-angle beam's eye view (BEV) MV cine images acquired from the treatment beam together with the orthogonally acquired limited-angle kV projections to reconstruct 4D-CBCT images for target verification during treatment...
June 2016: Medical Physics
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