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https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#1
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/28096728/high-resolution-imaging-of-neural-anatomy-and-pathology-of-the-neck
#2
REVIEW
Jeong Hyun Lee, Kai-Lung Cheng, Young Jun Choi, Jung Hwan Baek
The neck has intricately connected neural structures, including cervical and brachial plexi, the sympathetic system, lower cranial nerves, and their branches. Except for brachial plexus, there has been little research regarding the normal imaging appearance or corresponding pathologies of neural structures in the neck. The development in imaging techniques with better spatial resolution and signal-to-noise ratio has made it possible to see many tiny nerves to predict complications related to image-guided procedures and to better assess treatment response, especially in the management of oncology patients...
January 2017: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
https://www.readbyqxmd.com/read/28073579/robustness-of-4d-optimized-scanned-carbon-ion-beam-therapy-against-interfractional-changes-in-lung-cancer
#3
Christian Graeff
BACKGROUND AND PURPOSE: Moving targets could be conformally treated with actively scanned carbon ion beams using 4D-optimization. As this heavily exploits 4D-CTs, an important question is whether the conformity also upholds in the context of interfractional changes, i.e. variable positioning, anatomy and breathing patterns. MATERIALS AND METHODS: In 4 lung cancer patients, 6 weekly 4D-CTs were available. 4D-CTs and their phases were non-rigidly registered to propagate contours and 4D-doses...
January 7, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28066676/image-guided-localization-of-small-lung-nodules-in-video-assisted-thoracic-surgery
#4
REVIEW
Ze-Rui Zhao, Rainbow W H Lau, Peter S Y Yu, Randolph H L Wong, Calvin S H Ng
The advancement of imaging technology has recently facilitated single port minimally-invasive thoracic surgery techniques. Cone-beam computed tomography (CBCT) shows promising results in visualizing the target lesion and its surrounding critical anatomy, with an error of less than 2 mm. The integration of CBCT with the operating room (OR) to form the hybrid OR, provides unparalleled real-time imaging of the patient, which can be used with electromagnetic navigation bronchoscopy to confirm successful navigation and increase procedural accuracy particularly for small peripheral pulmonary targets...
October 2016: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28066675/techniques-of-stapler-based-navigational-thoracoscopic-segmentectomy-using-virtual-assisted-lung-mapping-val-map
#5
REVIEW
Masaaki Sato, Tomonori Murayama, Jun Nakajima
Anatomical segmentectomies play an important role in oncological lung resection, particularly for ground-glass types of primary lung cancers. This operation can also be applied to metastatic lung tumors deep in the lung. Virtual assisted lung mapping (VAL-MAP) is a novel technique that allows for bronchoscopic multi-spot dye markings to provide "geometric information" to the lung surface, using three-dimensional virtual images. In addition to wedge resections, VAL-MAP has been found to be useful in thoracoscopic segmentectomies, particularly complex segmentectomies, such as combined subsegmentectomies or extended segmentectomies...
October 2016: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28066622/the-role-bronchoscopy-in-the-diagnosis-of-airway-disease-in-children
#6
REVIEW
Tutku Soyer
Bronchoscopy is endoscopic examination of airways that allows both diagnostic and interventional procedures in the evaluation of airway disease in children. It can be performed with either rigid or flexible instruments, depending on the particular needs of patients and skills of bronchoscopist. In addition to visualization of airways, bronchoscopy enables to obtain specimens from lungs and distal airways. Bronchoalveolar lavage (BAL) yields samples from surfaces of the alveoli and aids differential diagnosis of various pulmonary disease...
November 2016: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28048756/su-f-j-66-anatomy-deformation-based-comparison-between-one-step-and-two-step-optimization-for-online-art
#7
Z Feng, G Yu, S Qin, C Ma, J Zhu, Y Yin, D Li
PURPOSE: This study investigated that how the quality of adapted plan was affected by inter-fractional anatomy deformation by using one-step and two-step optimization for on line adaptive radiotherapy (ART) procedure. METHODS: 10 lung carcinoma patients were chosen randomly to produce IMRT plan by one-step and two-step algorithms respectively, and the prescribed dose was set as 60 Gy on the planning target volume (PTV) for all patients. To simulate inter-fractional target deformation, four specific cases were created by systematic anatomy variation; including target superior shift 0...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048554/th-ab-202-03-a-novel-tool-for-computing-deliverable-doses-in-dynamic-mlc-tracking-treatments
#8
M Fast, C Kamerling, S Crijns, M Menten, S Nill, B Raaymakers, U Oelfke
PURPOSE: In tracked dynamic multi-leaf collimator (MLC) treatments, segments are continuously adapted to the target centroid motion in beams-eye-view. On-the-fly segment adaptation, however, potentially induces dosimetric errors due to the finite MLC leaf width and non-rigid target motion. In this study, we outline a novel tool for computing the 4d dose of lung SBRT plans delivered with MLC tracking. METHODS: The following automated workflow was developed: A) centroid tracking, where the initial segments are morphed to each 4dCT phase based on the beams-eye-view GTV shift (followed by a dose calculation on each phase); B) re-optimized tracking, in which all morphed initial plans from (A) are further optimised ("warm-started") in each 4dCT phase using the initial optimisation parameters but phase-specific volume definitions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048519/su-f-t-316-a-model-to-deal-with-dosimetric-and-delivery-uncertainties-in-radiotherapy-treatment-planning
#9
P Haering, C Lang, M Splinter
PURPOSE: The conventional way of dealing with uncertainties resulting from dose calculation or beam delivery in IMRT, is to do verification measurements for the plan in question. Here we present an alternative based on recommendations given in the AAPM 142 report and treatment specific parameters that model the uncertainties for the plan delivery. METHODS: Basis of the model is the assignment of uncertainty parameters to all segment fields or control point sequences of a plan...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048518/th-cd-209-05-impact-of-spot-size-and-spacing-on-the-quality-of-robustly-optimized-intensity-modulated-proton-therapy-plans-for-lung-cancer
#10
W Liu, S Schild, J Chang, Z Liao, X Ding, Y Hu, J Shen, S Korte, N Sahoo, W Wong, M Herman, M Bues
PURPOSE: To investigate how spot size and spacing affect plan quality, especially, plan robustness and the impact of interplay effect, of robustly-optimized intensity-modulated proton therapy (IMPT) plans for lung cancer. METHODS: Two robustly-optimized IMPT plans were created for 10 lung cancer patients: (1) one for a proton beam with in-air energy dependent large spot size at isocenter (σ: 5-15 mm) and spacing (1.53σ); (2) the other for a proton beam with small spot size (σ: 2-6 mm) and spacing (5 mm)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048472/tu-h-campus-jep3-04-factors-predicting-a-need-for-treatment-replanning-with-proton-radiotherapy-for-lung-cancer
#11
C Teng, G Janssens, C Ainsley, B Teo, G Valdes, B Burgdorf, A Berman, W Levin, Y Xiao, L Lin, P Gabriel, C Simone, T Solberg
PURPOSE: Proton dose distribution is sensitive to tumor regression and tissue and normal anatomy changes. Replanning is sometimes necessary during treatment to ensure continue tumor coverage or avoid overtreatment of organs at risk (OARs). We investigated action thresholds for replanning and identified both dosimetric and non-dosimetric metrics that would predict a need for replan. METHODS: All consecutive lung cancer patients (n = 188) who received definitive proton radiotherapy and had more than two evaluation CT scans at the Roberts Proton Therapy Center (Philadelphia, USA) from 2011 to 2015 were included in this study...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048469/th-cd-207a-08-simulated-real-time-image-guidance-for-lung-sbrt-patients-using-scatter-imaging
#12
G Redler, G Cifter, A Templeton, C Lee, D Bernard, Y Liao, H Zhen, J Turian, J Chu
PURPOSE: To develop a comprehensive Monte Carlo-based model for the acquisition of scatter images of patient anatomy in real-time, during lung SBRT treatment. METHODS: During SBRT treatment, images of patient anatomy can be acquired from scattered radiation. To rigorously examine the utility of scatter images for image guidance, a model is developed using MCNP code to simulate scatter images of phantoms and lung cancer patients. The model is validated by comparing experimental and simulated images of phantoms of different complexity...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048277/mo-fg-bra-06-electromagnetic-beacon-insertion-in-lung-cancer-patients-and-resultant-surrogacy-errors-for-dynamic-mlc-tumour-tracking
#13
N Hardcastle, J Booth, V Caillet, R O'Brien, C Haddad, C Crasta, K Szymura, P Keall
PURPOSE: To assess endo-bronchial electromagnetic beacon insertion and to quantify the geometric accuracy of using beacons as a surrogate for tumour motion in real-time multileaf collimator (MLC) tracking of lung tumours. METHODS: The LIGHT SABR trial is a world-first clinical trial in which the MLC leaves move with lung tumours in real time on a standard linear accelerator. Tracking is performed based on implanted electromagnetic beacons (CalypsoTM, Varian Medical Systems, USA) as a surrogate for tumour motion...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048172/mo-fg-bra-01-4d-monte-carlo-simulations-for-verification-of-dose-delivered-to-a-moving-anatomy
#14
S Gholampourkashi, J E Cygler, J Belec, M Vujicic, Heath
PURPOSE: To validate 4D Monte Carlo (MC) simulations of dose delivery by an Elekta Agility linear accelerator to a moving phantom. METHODS: Monte Carlo simulations were performed using the 4DdefDOSXYZnrc/EGSnrc user code which samples a new geometry for each incident particle and calculates the dose in a continuously moving anatomy. A Quasar respiratory motion phantom with a lung insert containing a 3 cm diameter tumor was used for dose measurements on an Elekta Agility linac with the phantom in stationary and moving states...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048113/su-f-i-44-using-the-air-signal-to-characterize-image-noise-in-ct
#15
T Szczykutowicz, A Malkus
PURPOSE: With increasing emphasis on CT image quality and low dose, quality activities analyzing noise levels in images will need to be increasingly automated. This work describes a new automated method for characterizing noise in CT. To obviate the need to segment out anatomical structure, this work introduces the use of noise statistics of air to understand the noise in the scanned object. METHODS: Scans of a uniform water phantom were acquired at four dose levels...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048098/su-f-j-67-dosimetric-changes-during-radiotherapy-in-lung-cancer-patients-with-atelectasis
#16
C Guy, E Weiss, N Jan, L Reshko, G Christensen, G Hugo
PURPOSE: Large geometric changes which occur during thoracic radiotherapy alter normal anatomy and target position and may induce clinically important dose changes. This study investigates variation of organ-at-risk (OAR) dose caused by atelectasis resolution during radiotherapy. METHODS: 3D IMRT treatment plans were obtained for 14 non-small-cell lung cancer patients. Dose of the clinical plan was recalculated on a baseline scan in which lung was collapsed and on a midtreatment scan in which lung re-aeration had occurred...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047525/su-g-bra-11-tumor-tracking-in-an-iterative-volume-of-interest-based-4d-cbct-reconstruction
#17
R Martin, M Ahmad, T Pan
PURPOSE: 4D CBCT can allow evaluation of tumor motion immediately prior to radiation therapy, but suffers from heavy artifacts that limit its ability to track tumors. Various iterative and compressed sensing reconstructions have been proposed to reduce these artifacts, but are costly time-wise and can degrade the image quality of bony anatomy for alignment with regularization. We have previously proposed an iterative volume of interest (I4D VOI) method which minimizes reconstruction time and maintains image quality of bony anatomy by focusing a 4D reconstruction within a VOI...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047092/su-f-t-417-dosimetric-evaluation-of-dose-to-medium-vs-dose-to-water-using-acuros-xb-for-lung-spine-and-head-and-neck-plans
#18
S Yu, D Rosenzweig, M Pacella
PURPOSE: This study evaluates the dosimetric differences between dose-to-medium (Dm) and conventional dose-to-water (Dw) reporting using Varian's Acuros XB (AXB) dose calculation algorithm with actual patient treatment plans. METHODS: Twelve patients were selected: four head-and-neck (HN) (2 Gy × 33-35 fractions), four lung SBRT (10-12 Gy × 5 fractions) and four spine SBRT (6-8 Gy × 5 fractions) cases. All treatment plans were optimized using the Varian Eclipse Progressive Resolution Optimizer (version 13...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047060/su-c-209-02-3d-fluoroscopic-image-generation-from-patient-specific-4dcbct-based-motion-models-derived-from-clinical-patient-images
#19
S Dhou, D Ionascu, W Cai, M Hurwitz, C Williams, J Lewis
PURPOSE: We develop a method to generate time varying volumetric images (3D fluoroscopic images) using patient-specific motion models derived from four-dimensional cone-beam CT (4DCBCT). METHODS: Motion models are derived by selecting one 4DCBCT phase as a reference image, and registering the remaining images to it. Principal component analysis (PCA) is performed on the resultant displacement vector fields (DVFs) to create a reduced set of PCA eigenvectors that capture the majority of respiratory motion...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047009/su-f-j-181-an-alternative-patient-alignment-tool-on-tomotherapy-the-first-in-human-megavoltage-topogram-acquisition
#20
L Yang, D Low, P Lee, D Ruan, R Chin, T Kaprealian, M Kamrava, P Kupelian, P Beron, M Steinberg, A Chen, N Agazaryan, S Ray, X Qi
PURPOSE: To show the first in-human Megavoltage (MV)-Topogram acquisition for the evaluation of the potential for MV-Topogram-based alignment as an alternative to MVCT for reducing dose and imaging time. METHODS: A lung cancer patient was enrolled in an ongoing IRB-approved clinical trial at our institute. The patient was set up using the clinical protocol employing positioning lasers. 3.2mm diameter tungsten spheres were placed on the patient's skin at their alignment tattoos to check surface-based marker concordance between topograms and MVCT...
June 2016: Medical Physics
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