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Image Guided Radiotherapy

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https://www.readbyqxmd.com/read/28102960/nine-degrees-of-freedom-flexmap-for-a-cone-beam-computed-tomography-imaging-device-with-independently-movable-source-and-detector
#1
Peter Keuschnigg, Daniel Kellner, Karl Fritscher, Andrea Zechner, Ulrich Mayer, Philipp Huber, Felix Sedlmayer, Heinz Deutschmann, Philipp Steininger
PURPOSE: Couch-mounted cone-beam computed tomography (CBCT) imaging devices with independently rotatable x-ray source and flat-panel detector arms for acquisitions of arbitrary regions of interest (ROI) have recently been introduced in image-guided radiotherapy (IGRT). This work analyzes mechanical limitations and gravity-induced effects influencing the geometric accuracy of images acquired with arbitrary angular constellations of source and detector in nonisocentric trajectories, which is considered essential for IGRT...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28074785/deformable-registration-of-ct-and-cone-beam-ct-with-local-intensity-matching
#2
Seyoun Park, William Plishker, Harry Quon, John Wong, Raj Shekhar, Junghoon Lee
Cone-beam CT (CBCT) is a widely used intra-operative imaging modality in image-guided radiotherapy and surgery. A short scan followed by a filtered-backprojection is typically used for CBCT reconstruction. While data on the mid-plane (plane of source-detector rotation) is complete, off-mid-planes undergo different information deficiency and the computed reconstructions are approximate. This causes different reconstruction artifacts at off-mid-planes depending on slice locations, and therefore impedes accurate registration between CT and CBCT...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28069053/influence-of-daily-imaging-on-plan-quality-and-normal-tissue-toxicity-for-prostate-cancer-radiotherapy
#3
Katharina Bell, Marina Heitfeld, Norbert Licht, Christian RĂ¼be, 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/28060412/optimizing-dual-energy-x-ray-parameters-for-the-exactrac-clinical-stereoscopic-imaging-system-to-enhance-soft-tissue-imaging
#4
Wesley A Bowman, James L Robar, Mike Sattarivand
PURPOSE: Stereoscopic x-ray image guided radiotherapy for lung tumors is often hindered by bone overlap and limited soft tissue contrast. This study aims to evaluate the feasibility of dual-energy imaging techniques and to optimize parameters of the ExacTrac stereoscopic imaging system to enhance soft tissue imaging for application to lung stereotactic body radiation therapy. METHODS: Simulated spectra and a physical lung phantom were used to optimize filter material, thickness, tube potentials, and weighting factors to obtain bone subtracted dual-energy images...
January 6, 2017: Medical Physics
https://www.readbyqxmd.com/read/28048919/su-g-jep3-05-geometry-based-transperineal-ultrasound-probe-positioning-for-image-guided-radiotherapy
#5
S Camps, F Verhaegen, P de With, D Fontanarosa
PURPOSE: The use of ultrasound (US) imaging in radiotherapy is not widespread, primarily due to the need for skilled operators performing the scans. Automation of probe positioning has the potential to remove this need and minimize operator dependence. We introduce an algorithm for obtaining a US probe position that allows good anatomical structure visualization based on clinical requirements. The first application is on 4D transperineal US images of prostate cancer patients. METHODS: The algorithm calculates the probe position and orientation using anatomical information provided by a reference CT scan, always available in radiotherapy workflows...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048884/th-ef-204-02-small-field-radiation-therapy-physics-and-recent-recommendations-from-iaea-and-icru
#6
J Seuntjens
: Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048869/su-f-j-145-mri-guided-interventional-boost-radiotherapy-for-rectal-cancer-investigating-the-feasibility-of-adapting-the-anatomy
#7
J J E Kleijnen, A M Couwenberg, B van Asselen, J J W Lagendijk, M Intven, B W Raaymakers
PURPOSE: The recent development of an MRI-linac allows adaptation of treatments to the anatomy of the moment. This anatomy, in turn, could be altered into a more favorable situation for radiotherapy purposes. The purpose of this study is to investigate the potential dosimetric benefits of manipulating rectal anatomy in MRI-guided interventional external-beam radiotherapy for rectal cancer. METHODS: For this retrospective analysis, four patients (1M/3F) diagnosed with rectal cancer were included...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048862/th-e-202-02-the-use-of-hypoxia-pet-imaging-for-radiotherapy
#8
J Humm
: PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss: 1. Pitfalls and remedies in PET/CT imaging for RT planning 2. The use of hypoxia PET imaging for radiotherapy 3. PET for tumor response evaluation The first presentation will address the issue of mis-registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image-guidance in radiation therapy...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048833/su-g-iep1-13-sub-nyquist-dynamic-mri-via-prior-rank-intensity-and-sparsity-model-prism
#9
B Jiang, H Gao
PURPOSE: Accelerated dynamic MRI is important for MRI guided radiotherapy. Inspired by compressive sensing (CS), sub-Nyquist dynamic MRI has been an active research area, i.e., sparse sampling in k-t space for accelerated dynamic MRI. This work is to investigate sub-Nyquist dynamic MRI via a previously developed CS model, namely Prior Rank, Intensity and Sparsity Model (PRISM). METHODS: The proposed method utilizes PRISM with rank minimization and incoherent sampling patterns for sub-Nyquist reconstruction...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048815/su-f-j-59-assessment-of-dose-response-distribution-in-individual-human-tumor
#10
D Yan, S Chen, D Krauss, P Chen, G Wilson
PURPOSE: To fulfill precision radiotherapy via adaptive dose painting by number, voxel-by-voxel dose response or radio-sensitivity in individual human tumor needs to be determined in early treatment to guide treatment adaptation. In this study, multiple FDG PET images obtained pre- and weekly during the treatment course were utilized to determine the distribution/spectrum of dose response parameters in individual human tumors. METHODS: FDG PET/CT images of 18 HN cancer patients were used in the study...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048768/su-f-i-03-correction-of-intra-fractional-set-up-errors-and-target-coverage-based-on-cone-beam-computed-tomography-for-cervical-cancer-patients
#11
J Y Zhang, D L Hong
PURPOSE: The purpose of this study is to investigate the patient set-up error and interfraction target coverage in cervical cancer using image-guided adaptive radiotherapy (IGART) with cone-beam computed tomography (CBCT). METHODS: Twenty cervical cancer patients undergoing intensity modulated radiotherapy (IMRT) were randomly selected. All patients were matched to the isocenter using laser with the skin markers. Three dimensional CBCT projections were acquired by the Varian Truebeam treatment system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048724/su-f-j-84-comparison-of-quantitative-deformable-image-registration-evaluation-tools-application-to-prostate-igart
#12
N Dogan, E Weiss, W Sleeman, G Christensen, J Williamson, J Ford
PURPOSE: Errors in displacement vector fields (DVFs) generated by Deformable Image Registration (DIR) algorithms can give rise to significant uncertainties in contour propagation and dose accumulation in Image-Guided Adaptive Radiotherapy (IGART). The purpose of this work is to assess the accuracy of two DIR algorithms using a variety of quality metrics for prostate IGART. METHODS: Pelvic CT images were selected from an anonymized database of nineteen prostate patients who underwent 8-12 serial scans during radiotherapy...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048698/tu-fg-bra-02-assure-the-quality-of-treatment-planning-when-time-is-constrained
#13
J Chang
Optimizing Radiation Therapy Process The radiotherapy (RT) process has evolved over the years with innovations in CT and MR simulations, treatment planning, and treatment delivery. Image-Guided Radiotherapy (IGRT) has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body Radiotherapy (SBRT) and Stereotactic Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the simulation/plan/treatment even if the number of treatments per day remains the same...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048690/su-f-j-22-lung-volumevariability-assessed-by-bh-cbct-in-3d-surface-image-guided-deep-inspirationbreath-hold-dibh-radiotherapy-for-left-sided-breast-cancer
#14
A Gutierrez, D Stanley, N Papanikolaou, R Crownover
PURPOSE: With the increasing use of DIBH techniques for left-sided breast cancer, 3D surface-image guided DIBH techniques have improved patient setup and facilitated DIBH radiation delivery. However, quantification of the daily separation between the heart and left breast still presents a challenge. One method of assuring separation is to ensure consistent left lung filling. With this in mind, the aim of this study is to retrospectively quantify left lung volume from weekly breath hold-CBCTs (bh-CBCT) of left-sided breast patients treated using a 3D surface imaging system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048660/tu-b-201-01-an-overview-of-tg-180
#15
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/28048532/su-f-t-396-impact-of-shoulder-deformation-for-head-and-neck-vmat
#16
Y Uchida, H Tachibana
PURPOSE: For head and neck VMAT (HN-VMAT), variations of position and deformation of patient's shoulders is a concern to affect inaccuracy of dose distribution. It has been reported that the setup error of the shoulders was variable from 5 mm - 1 cm. The beams of the HN-VMAT pass through the shoulders. We assessed the impact of shoulder deformation to dose distribution for HN-VMAT. METHODS: One HN-VMAT plan was generated using a patient's CT. The patient's CT was deformed using ImSimQA (Oncology Systems Limited, Shrewsbury, Shropshire, UK) to generate several patterns of the shoulders' deformations when the right and left humeral heads were shifted with 3, 6, and 15 mm in the superior and inferior directions (SI), 3, 5, and 15 mm in the anterior and posterior directions (AP), and 5 and 15 mm in the right or left direction (LR)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048487/su-c-bra-03-an-automated-and-quick-contour-errordetection-for-auto-segmentation-in-online-adaptive-radiotherapy
#17
J Zhang, O Ates, X Li
PURPOSE: To develop a tool that can quickly and automatically assess contour quality generated from auto segmentation during online adaptive replanning. METHODS: Due to the strict time requirement of online replanning and lack of 'ground truth' contours in daily images, our method starts with assessing image registration accuracy focusing on the surface of the organ in question. Several metrics tightly related to registration accuracy including Jacobian maps, contours shell deformation, and voxel-based root mean square (RMS) analysis were computed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048426/we-ab-207a-07-a-planning-ct-guided-scatter-artifact-correction-method-for-cbct-images
#18
X Yang, T Liu, X Dong, E Elder, W Curran, A Dhabaan
PURPOSE: Cone beam computed tomography (CBCT) imaging is on increasing demand for high-performance image-guided radiotherapy such as online tumor delineation and dose calculation. However, the current CBCT imaging has severe scatter artifacts and its current clinical application is therefore limited to patient setup based mainly on the bony structures. This study's purpose is to develop a CBCT artifact correction method. METHODS: The proposed scatter correction method utilizes the planning CT to improve CBCT image quality...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048423/we-fg-bra-08-potential-role-of-the-glycolytic-oscillator-in-acute-hypoxia-in-tumors
#19
L Che Fru, E Adamson, D Campos, S Fain, S Jacques, A van der Kogel, K Nickel, C Song, R Kimple, M Kissick
PURPOSE: Oscillatory dynamics in acute hypoxia have been observed, but poorly understood. They have mostly been attributed to vascular perturbations, but no link has yet been made to metabolic causes. We set out to determine the fundamental frequencies and test for coherence in tumor oxygen dynamics and spatial properties. METHODS: Severe combined immunodeficient (SCID) mice were inoculated onto bilateral flanks with human derived head and neck carcinoma (UW-SCC22) cell line xenografts...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048417/th-e-202-00-pet-for-radiation-therapy
#20
Wei Lu
: PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss: 1. Pitfalls and remedies in PET/CT imaging for RT planning 2. The use of hypoxia PET imaging for radiotherapy 3. PET for tumor response evaluation The first presentation will address the issue of mis-registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image-guidance in radiation therapy...
June 2016: Medical Physics
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