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AAPM Task Group 334: A guidance document to using radiotherapy immobilization devices and accessories in an MR environment. Med Phys 2024. [PMID: 38648857 DOI: 10.1002/mp.17061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/13/2023] [Accepted: 03/28/2024] [Indexed: 04/25/2024] Open
Abstract
Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR-linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations. The determination of the safety profile and considerations often falls to the medical physicist or other support staff members who at a minimum should be a Level 2 personnel as per the ACR. The purpose of this guidance document will be to help guide the user in making determinations on MR Safety labeling (i.e., MR Safe, Conditional, or Unsafe) including standard testing, and verification of image quality, when using RT immobilization devices and accessories in an MR environment.
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Impact of proton PBS machine operating parameters on the effectiveness of layer rescanning for interplay effect mitigation in lung SBRT treatment. J Appl Clin Med Phys 2024:e14342. [PMID: 38590112 DOI: 10.1002/acm2.14342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/07/2024] [Accepted: 03/13/2024] [Indexed: 04/10/2024] Open
Abstract
BACKGROUND Rescanning is a common technique used in proton pencil beam scanning to mitigate the interplay effect. Advances in machine operating parameters across different generations of particle therapy systems have led to improvements in beam delivery time (BDT). However, the potential impact of these improvements on the effectiveness of rescanning remains an underexplored area in the existing research. METHODS We systematically investigated the impact of proton machine operating parameters on the effectiveness of layer rescanning in mitigating interplay effect during lung SBRT treatment, using the CIRS phantom. Focused on the Hitachi synchrotron particle therapy system, we explored machine operating parameters from our institution's current (2015) and upcoming systems (2025A and 2025B). Accumulated dynamic 4D dose were reconstructed to assess the interplay effect and layer rescanning effectiveness. RESULTS Achieving target coverage and dose homogeneity within 2% deviation required 6, 6, and 20 times layer rescanning for the 2015, 2025A, and 2025B machine parameters, respectively. Beyond this point, further increasing the number of layer rescanning did not further improve the dose distribution. BDTs without rescanning were 50.4, 24.4, and 11.4 s for 2015, 2025A, and 2025B, respectively. However, after incorporating proper number of layer rescanning (six for 2015 and 2025A, 20 for 2025B), BDTs increased to 67.0, 39.6, and 42.3 s for 2015, 2025A, and 2025B machine parameters. Our data also demonstrated the potential problem of false negative and false positive if the randomness of the respiratory phase at which the beam is initiated is not considered in the evaluation of interplay effect. CONCLUSION The effectiveness of layer rescanning for mitigating interplay effect is affected by machine operating parameters. Therefore, past clinical experiences may not be applicable to modern machines.
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A high-resolution cone beam computed tomography (HRCBCT) reconstruction framework for CBCT-guided online adaptive therapy. Med Phys 2023; 50:6490-6501. [PMID: 37690458 DOI: 10.1002/mp.16734] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 08/18/2023] [Accepted: 08/19/2023] [Indexed: 09/12/2023] Open
Abstract
BACKGROUND Kilo-voltage cone-beam computed tomography (CBCT) is a prevalent modality used for adaptive radiotherapy (ART) due to its compatibility with linear accelerators and ability to provide online imaging. However, the widely-used Feldkamp-Davis-Kress (FDK) reconstruction algorithm has several limitations, including potential streak aliasing artifacts and elevated noise levels. Iterative reconstruction (IR) techniques, such as total variation (TV) minimization, dictionary-based methods, and prior information-based methods, have emerged as viable solutions to address these limitations and improve the quality and applicability of CBCT in ART. PURPOSE One of the primary challenges in IR-based techniques is finding the right balance between minimizing image noise and preserving image resolution. To overcome this challenge, we have developed a new reconstruction technique called high-resolution CBCT (HRCBCT) that specifically focuses on improving image resolution while reducing noise levels. METHODS The HRCBCT reconstruction technique builds upon the conventional IR approach, incorporating three components: the data fidelity term, the resolution preservation term, and the regularization term. The data fidelity term ensures alignment between reconstructed values and measured projection data, while the resolution preservation term exploits the high resolution of the initial Feldkamp-Davis-Kress (FDK) algorithm. The regularization term mitigates noise during the IR process. To enhance convergence and resolution at each iterative stage, we applied Iterative Filtered Backprojection (IFBP) to the data fidelity minimization process. RESULTS We evaluated the performance of the proposed HRCBCT algorithm using data from two physical phantoms and one head and neck patient. The HRCBCT algorithm outperformed all four different algorithms; FDK, Iterative Filtered Back Projection (IFBP), Compressed Sensing based Iterative Reconstruction (CSIR), and Prior Image Constrained Compressed Sensing (PICCS) methods in terms of resolution and noise reduction for all data sets. Line profiles across three line pairs of resolution revealed that the HRCBCT algorithm delivered the highest distinguishable line pairs compared to the other algorithms. Similarly, the Modulation Transfer Function (MTF) measurements, obtained from the tungsten wire insert on the CatPhan 600 physical phantom, showed a significant improvement with HRCBCT over traditional algorithms. CONCLUSION The proposed HRCBCT algorithm offers a promising solution for enhancing CBCT image quality in adaptive radiotherapy settings. By addressing the challenges inherent in traditional IR methods, the algorithm delivers high-definition CBCT images with improved resolution and reduced noise throughout each iterative step. Implementing the HR CBCT algorithm could significantly impact the accuracy of treatment planning during online adaptive therapy.
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Technical note: Progressive deep learning: An accelerated training strategy for medical image segmentation. Med Phys 2023; 50:5075-5087. [PMID: 36763566 DOI: 10.1002/mp.16267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 12/30/2022] [Accepted: 01/24/2023] [Indexed: 02/11/2023] Open
Abstract
BACKGROUND Recent advancements in Deep Learning (DL) methodologies have led to state-of-the-art performance in a wide range of applications especially in object recognition, classification, and segmentation of medical images. However, training modern DL models requires a large amount of computation and long training times due to the complex nature of network structures and the large number of training datasets involved. Moreover, it is an intensive, repetitive manual process to select the optimized configuration of hyperparameters for a given DL network. PURPOSE In this study, we present a novel approach to accelerate the training time of DL models via the progressive feeding of training datasets based on similarity measures for medical image segmentation. We term this approach Progressive Deep Learning (PDL). METHODS The two-stage PDL approach was tested on the auto-segmentation task for two imaging modalities: CT and MRI. The training datasets were ranked according to similarity measures between each sample based on Mean Square Error (MSE), Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index (SSIM), and the Universal Quality Image Index (UQI) values. At the start of the training process, a relatively coarse sampling of training datasets with higher ranks was used to optimize the hyperparameters of the DL network. Following this, the samples with higher ranks were used in step 1 to yield accelerated loss minimization in early training epochs and the total dataset was added in step 2 for the remainder of training. RESULTS Our results demonstrate that the PDL approach can reduce the training time by nearly half (∼49%) and can predict segmentations (CT U-net/DenseNet dice coefficient: 0.9506/0.9508, MR U-net/DenseNet dice coefficient: 0.9508/0.9510) without major statistical difference (Wilcoxon signed-rank test) compared to the conventional DL approach. The total training times with a fixed cutoff at 0.95 DSC for the CT dataset using DenseNet and U-Net architectures, respectively, were 17 h, 20 min and 4 h, 45 min in the conventional case compared to 8 h, 45 min and 2 h, 20 min with PDL. For the MRI dataset, the total training times using the same architectures were 2 h, 54 min and 52 min in the conventional case and 1 h, 14 min and 25 min with PDL. CONCLUSION The proposed PDL training approach offers the ability to substantially reduce the training time for medical image segmentation while maintaining the performance achieved in the conventional case.
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Segmentation by test-time optimization for CBCT-based adaptive radiation therapy. Med Phys 2023; 50:1947-1961. [PMID: 36310403 PMCID: PMC10121749 DOI: 10.1002/mp.15960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 08/02/2022] [Accepted: 08/21/2022] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Online adaptive radiotherapy (ART) requires accurate and efficient auto-segmentation of target volumes and organs-at-risk (OARs) in mostly cone-beam computed tomography (CBCT) images, which often have severe artifacts and lack soft-tissue contrast, making direct segmentation very challenging. Propagating expert-drawn contours from the pretreatment planning CT through traditional or deep learning (DL)-based deformable image registration (DIR) can achieve improved results in many situations. Typical DL-based DIR models are population based, that is, trained with a dataset for a population of patients, and so they may be affected by the generalizability problem. METHODS In this paper, we propose a method called test-time optimization (TTO) to refine a pretrained DL-based DIR population model, first for each individual test patient, and then progressively for each fraction of online ART treatment. Our proposed method is less susceptible to the generalizability problem and thus can improve overall performance of different DL-based DIR models by improving model accuracy, especially for outliers. Our experiments used data from 239 patients with head-and-neck squamous cell carcinoma to test the proposed method. First, we trained a population model with 200 patients and then applied TTO to the remaining 39 test patients by refining the trained population model to obtain 39 individualized models. We compared each of the individualized models with the population model in terms of segmentation accuracy. RESULTS The average improvement of the Dice similarity coefficient (DSC) and 95% Hausdorff distance (HD95) of segmentation can be up to 0.04 (5%) and 0.98 mm (25%), respectively, with the individualized models compared to the population model over 17 selected OARs and a target of 39 patients. Although the average improvement may seem mild, we found that the improvement for outlier patients with structures of large anatomical changes is significant. The number of patients with at least 0.05 DSC improvement or 2 mm HD95 improvement by TTO averaged over the 17 selected structures for the state-of-the-art architecture VoxelMorph is 10 out of 39 test patients. By deriving the individualized model using TTO from the pretrained population model, TTO models can be ready in about 1 min. We also generated the adapted fractional models for each of the 39 test patients by progressively refining the individualized models using TTO to CBCT images acquired at later fractions of online ART treatment. When adapting the individualized model to a later fraction of the same patient, the model can be ready in less than a minute with slightly improved accuracy. CONCLUSIONS The proposed TTO method is well suited for online ART and can boost segmentation accuracy for DL-based DIR models, especially for outlier patients where the pretrained models fail.
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Ensemble learning and personalized training for the improvement of unsupervised deep learning-based synthetic CT reconstruction. Med Phys 2023; 50:1436-1449. [PMID: 36336718 DOI: 10.1002/mp.16087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 08/22/2022] [Accepted: 10/19/2022] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND The growing adoption of magnetic resonance imaging (MRI)-guided radiation therapy (RT) platforms and a focus on MRI-only RT workflows have brought the technical challenge of synthetic computed tomography (sCT) reconstruction to the forefront. Unpaired-data deep learning-based approaches to the problem offer the attractive characteristic of not requiring paired training data, but the gap between paired- and unpaired-data results can be limiting. PURPOSE We present two distinct approaches aimed at improving unpaired-data sCT reconstruction results: a cascade ensemble that combines multiple models and a personalized training strategy originally designed for the paired-data setting. METHODS Comparisons are made between the following models: (1) the paired-data fully convolutional DenseNet (FCDN), (2) the FCDN with the Intentional Deep Overfit Learning (IDOL) personalized training strategy, (3) the unpaired-data CycleGAN, (4) the CycleGAN with the IDOL training strategy, and (5) the CycleGAN as an intermediate model in a cascade ensemble approach. Evaluation of the various models over 25 total patients is carried out using a five-fold cross-validation scheme, with the patient-specific IDOL models being trained for the five patients of fold 3, chosen at random. RESULTS In both the paired- and unpaired-data settings, adopting the IDOL training strategy led to improvements in the mean absolute error (MAE) between true CT images and sCT outputs within the body contour (mean improvement, paired- and unpaired-data approaches, respectively: 38%, 9%) and in regions of bone (52%, 5%), the peak signal-to-noise ratio (PSNR; 15%, 7%), and the structural similarity index (SSIM; 6%, <1%). The ensemble approach offered additional benefits over the IDOL approach in all three metrics (mean improvement over unpaired-data approach in fold 3; MAE: 20%; bone MAE: 16%; PSNR: 10%; SSIM: 2%), and differences in body MAE between the ensemble approach and the paired-data approach are statistically insignificant. CONCLUSIONS We have demonstrated that both a cascade ensemble approach and a personalized training strategy designed initially for the paired-data setting offer significant improvements in image quality metrics for the unpaired-data sCT reconstruction task. Closing the gap between paired- and unpaired-data approaches is a step toward fully enabling these powerful and attractive unpaired-data frameworks.
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Real-time liver tumor localization via a single x-ray projection using deep graph neural network-assisted biomechanical modeling. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac6b7b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/28/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective. Real-time imaging is highly desirable in image-guided radiotherapy, as it provides instantaneous knowledge of patients’ anatomy and motion during treatments and enables online treatment adaptation to achieve the highest tumor targeting accuracy. Due to extremely limited acquisition time, only one or few x-ray projections can be acquired for real-time imaging, which poses a substantial challenge to localize the tumor from the scarce projections. For liver radiotherapy, such a challenge is further exacerbated by the diminished contrast between the tumor and the surrounding normal liver tissues. Here, we propose a framework combining graph neural network-based deep learning and biomechanical modeling to track liver tumor in real-time from a single onboard x-ray projection. Approach. Liver tumor tracking is achieved in two steps. First, a deep learning network is developed to predict the liver surface deformation using image features learned from the x-ray projection. Second, the intra-liver deformation is estimated through biomechanical modeling, using the liver surface deformation as the boundary condition to solve tumor motion by finite element analysis. The accuracy of the proposed framework was evaluated using a dataset of 10 patients with liver cancer. Main results. The results show accurate liver surface registration from the graph neural network-based deep learning model, which translates into accurate, fiducial-less liver tumor localization after biomechanical modeling (<1.2 (±1.2) mm average localization error). Significance. The method demonstrates its potentiality towards intra-treatment and real-time 3D liver tumor monitoring and localization. It could be applied to facilitate 4D dose accumulation, multi-leaf collimator tracking and real-time plan adaptation. The method can be adapted to other anatomical sites as well.
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Intentional deep overfit learning (IDOL): A novel deep learning strategy for adaptive radiation therapy. Med Phys 2021; 49:488-496. [PMID: 34791672 DOI: 10.1002/mp.15352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 09/28/2021] [Accepted: 11/03/2021] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Applications of deep learning (DL) are essential to realizing an effective adaptive radiotherapy (ART) workflow. Despite the promise demonstrated by DL approaches in several critical ART tasks, there remain unsolved challenges to achieve satisfactory generalizability of a trained model in a clinical setting. Foremost among these is the difficulty of collecting a task-specific training dataset with high-quality, consistent annotations for supervised learning applications. In this study, we propose a tailored DL framework for patient-specific performance that leverages the behavior of a model intentionally overfitted to a patient-specific training dataset augmented from the prior information available in an ART workflow-an approach we term Intentional Deep Overfit Learning (IDOL). METHODS Implementing the IDOL framework in any task in radiotherapy consists of two training stages: (1) training a generalized model with a diverse training dataset of N patients, just as in the conventional DL approach, and (2) intentionally overfitting this general model to a small training dataset-specific the patient of interest ( N + 1 ) generated through perturbations and augmentations of the available task- and patient-specific prior information to establish a personalized IDOL model. The IDOL framework itself is task-agnostic and is, thus, widely applicable to many components of the ART workflow, three of which we use as a proof of concept here: the autocontouring task on replanning CTs for traditional ART, the MRI super-resolution (SR) task for MRI-guided ART, and the synthetic CT (sCT) reconstruction task for MRI-only ART. RESULTS In the replanning CT autocontouring task, the accuracy measured by the Dice similarity coefficient improves from 0.847 with the general model to 0.935 by adopting the IDOL model. In the case of MRI SR, the mean absolute error (MAE) is improved by 40% using the IDOL framework over the conventional model. Finally, in the sCT reconstruction task, the MAE is reduced from 68 to 22 HU by utilizing the IDOL framework. CONCLUSIONS In this study, we propose a novel IDOL framework for ART and demonstrate its feasibility using three ART tasks. We expect the IDOL framework to be especially useful in creating personally tailored models in situations with limited availability of training data but existing prior information, which is usually true in the medical setting in general and is especially true in ART.
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Abdominal synthetic CT reconstruction with intensity projection prior for MRI-only adaptive radiotherapy. Phys Med Biol 2021; 66. [PMID: 34530421 DOI: 10.1088/1361-6560/ac279e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/16/2021] [Indexed: 11/11/2022]
Abstract
Objective. Owing to the superior soft tissue contrast of MRI, MRI-guided adaptive radiotherapy (ART) is well-suited to managing interfractional changes in anatomy. An MRI-only workflow is desirable, but producing synthetic CT (sCT) data through paired data-driven deep learning (DL) for abdominal dose calculations remains a challenge due to the highly variable presence of intestinal gas. We present the preliminary dosimetric evaluation of our novel approach to sCT reconstruction that is well suited to handling intestinal gas in abdominal MRI-only ART.Approach. We utilize a paired data DL approach enabled by the intensity projection prior, in which well-matching training pairs are created by propagating air from MRI to corresponding CT scans. Evaluations focus on two classes: patients with (1) little involvement of intestinal gas, and (2) notable differences in intestinal gas presence between corresponding scans. Comparisons between sCT-based plans and CT-based clinical plans for both classes are made at the first treatment fraction to highlight the dosimetric impact of the variable presence of intestinal gas.Main results. Class 1 patients (n= 13) demonstrate differences in prescribed dose coverage of the PTV of 1.3 ± 2.1% between clinical plans and sCT-based plans. Mean DVH differences in all structures for Class 1 patients are found to be statistically insignificant. In Class 2 (n= 20), target coverage is 13.3 ± 11.0% higher in the clinical plans and mean DVH differences are found to be statistically significant.Significance. Significant deviations in calculated doses arising from the variable presence of intestinal gas in corresponding CT and MRI scans result in uncertainty in high-dose regions that may limit the effectiveness of adaptive dose escalation efforts. We have proposed a paired data-driven DL approach to sCT reconstruction for accurate dose calculations in abdominal ART enabled by the creation of a clinically unavailable training data set with well-matching representations of intestinal gas.
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Evaluation of super-resolution on 50 pancreatic cancer patients with real-time cine MRI from 0.35T MRgRT. Biomed Phys Eng Express 2021; 7:055020. [PMID: 34375963 DOI: 10.1088/2057-1976/ac1c51] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/10/2021] [Indexed: 12/25/2022]
Abstract
MR-guided radiotherapy (MRgRT) systems provide excellent soft tissue imaging immediately prior to and in real time during radiation delivery for cancer treatment. However, 2D cine MRI often has limited spatial resolution due to high temporal resolution. This work applies a super resolution machine learning framework to 3.5 mm pixel edge length, low resolution (LR), sagittal 2D cine MRI images acquired on a MRgRT system to generate 0.9 mm pixel edge length, super resolution (SR), images originally acquired at 4 frames per second (FPS). LR images were collected from 50 pancreatic cancer patients treated on a ViewRay MR-LINAC. SR images were evaluated using three methods. 1) The first method utilized intrinsic image quality metrics for evaluation. 2) The second used relative metrics including edge detection and structural similarity index (SSIM). 3) Finally, automatically generated tumor contours were created on both low resolution and super resolution images to evaluate target delineation and compared with DICE and SSIM. Intrinsic image quality metrics all had statistically significant improvements for SR images versus LR images, with mean (±1 SD) BRISQUE scores of 29.65 ± 2.98 and 42.48 ± 0.98 for SR and LR, respectively. SR images showed good agreement with LR images in SSIM evaluation, indicating there was not significant distortion of the images. Comparison of LR and SR images with paired high resolution (HR) 3D images showed that SR images had a mean (±1 SD) SSIM value of 0.633 ± 0.063 and LR a value of 0.587 ± 0.067 (p ≪ 0.05). Contours generated on SR images were also more robust to noise addition than those generated on LR images. This study shows that super resolution with a machine learning framework can generate high spatial resolution images from 4fps low spatial resolution cine MRI acquired on the ViewRay MR-LINAC while maintaining tumor contour quality and without significant acquisition or post processing delay.
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Development of Dosimetric Verification System for Patient-Specific Quality Assurance of High-Dose-Rate Brachytherapy. Front Oncol 2021; 11:647222. [PMID: 33768006 PMCID: PMC7985337 DOI: 10.3389/fonc.2021.647222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/15/2021] [Indexed: 11/21/2022] Open
Abstract
Purpose: The aim of this study was to develop a dosimetric verification system (DVS) using a solid phantom for patient-specific quality assurance (QA) of high-dose-rate brachytherapy (HDR-BT). Methods: The proposed DVS consists of three parts: dose measurement, dose calculation, and analysis. All the dose measurements were performed using EBT3 film and a solid phantom. The solid phantom made of acrylonitrile butadiene styrene (ABS, density = 1.04 g/cm3) was used to measure the dose distribution. To improve the accuracy of dose calculation by using the solid phantom, a conversion factor [CF(r)] according to the radial distance between the water and the solid phantom material was determined by Monte Carlo simulations. In addition, an independent dose calculation program (IDCP) was developed by applying the obtained CF(r). To validate the DVS, dosimetric verification was performed using gamma analysis with 3% dose difference and 3 mm distance-to-agreement criterion for three simulated cases: single dwell position, elliptical dose distribution, and concave elliptical dose distribution. In addition, the possibility of applying the DVS in the high-dose range (up to 15 Gy) was evaluated. Results: The CF(r) between the ABS and water phantom was 0.88 at 0.5 cm. The factor gradually increased with increasing radial distance and converged to 1.08 at 6.0 cm. The point doses 1 cm below the source were 400 cGy in the treatment planning system (TPS), 373.73 cGy in IDCP, and 370.48 cGy in film measurement. The gamma passing rates of dose distributions obtained from TPS and IDCP compared with the dose distribution measured by the film for the simulated cases were 99.41 and 100% for the single dwell position, 96.80 and 100% for the elliptical dose distribution, 88.91 and 99.70% for the concave elliptical dose distribution, respectively. For the high-dose range, the gamma passing rates in the dose distributions between the DVS and measurements were above 98% and higher than those between TPS and measurements. Conclusion: The proposed DVS is applicable for dosimetric verification of HDR-BT, as confirmed through simulated cases for various doses.
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Long-term clinical outcomes of endoscopic submucosal dissection for colorectal neoplasia with or without the hybrid technique. Colorectal Dis 2020; 22:2008-2017. [PMID: 32866340 DOI: 10.1111/codi.15339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/04/2020] [Accepted: 08/18/2020] [Indexed: 12/12/2022]
Abstract
AIM The main aim of this study was to compare the long-term outcome of a conventional colorectal endoscopic submucosal dissection (ESD) in which submucosal dissection was continued throughout until the completion of resection (ESD-T) to hybrid endoscopic submucosal dissection (ESD-H) in the colorectum. METHOD Medical records of 836 colorectal neoplasia patients treated by ESD-T or ESD-H were reviewed. ESD-H was defined as colorectal ESD with additional snaring in the final stage of the procedure. Primary outcomes were the overall and metastatic recurrence rates. Secondary outcomes were short-term outcomes such as the en bloc resection rate, procedure time and adverse events. RESULTS The overall recurrence rate was higher in the ESD-H than in the ESD-T group (5.7% vs 0.7%, P = 0.001). The metastatic recurrence rate showed no significant difference between these groups (1.4% vs 1.4%, P = 1.000). Multivariate analysis revealed that a failed en bloc resection (hazard ratio 24.097; 95% CI 5.446-106.237; P < 0.001) and larger tumour size (hazard ratio 1.042; 95% CI 1.014-1.070; P = 0.003) were independently associated with overall recurrence. The ESD-H group showed a lower en bloc resection rate (56.8% vs 96.5%, P < 0.001), shorter procedure time (45.6 vs 54.3 min, P < 0.001) and higher perforation rate (10.3% vs 6.0%, P = 0.029). CONCLUSION Although long-term outcomes in terms of overall recurrence are inferior following ESD-H, a failed en bloc resection and large tumour size are the only independent risk factors for recurrence. Further investigations are warranted to improve the long-term outcomes of ESD-H.
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Direct tumor visual feedback during free breathing in 0.35T MRgRT. J Appl Clin Med Phys 2020; 21:241-247. [PMID: 32931649 PMCID: PMC7592976 DOI: 10.1002/acm2.13016] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/12/2020] [Accepted: 07/29/2020] [Indexed: 12/25/2022] Open
Abstract
To present a tumor motion control system during free breathing using direct tumor visual feedback to patients in 0.35 T magnetic resonance-guided radiotherapy (MRgRT). We present direct tumor visualization to patients by projecting real-time cine MR images on an MR-compatible display system inside a 0.35 T MRgRT bore. The direct tumor visualization included anatomical images with a target contour and an auto-segmented gating contour. In addition, a beam-status sign was added for patient guidance. The feasibility was investigated with a six-patient clinical evaluation of the system in terms of tumor motion range and beam-on time. Seven patients without visual guidance were used for comparison. Positions of the tumor and the auto-segmented gating contour from the cine MR images were used in probability analysis to evaluate tumor motion control. In addition, beam-on time was recorded to assess the efficacy of the visual feedback system. The direct tumor visualization system was developed and implemented in our clinic. The target contour extended 3 mm outside of the gating contour for 33.6 ± 24.9% of the time without visual guidance, and 37.2 ± 26.4% of the time with visual guidance. The average maximum motion outside of the gating contour was 14.4 ± 11.1 mm without and 13.0 ± 7.9 mm with visual guidance. Beam-on time as a percentage was 43.9 ± 15.3% without visual guidance, and 48.0 ± 21.2% with visual guidance, but was not significantly different (P = 0.34). We demonstrated the clinical feasibility and potential benefits of presenting direct tumor visual feedback to patients in MRgRT. The visual feedback allows patients to visualize and attempt to minimize tumor motion in free breathing. The proposed system and associated clinical workflow can be easily adapted for any type of MRgRT.
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Abstract
Autophagy is an intracellular self-degradation process that is essential for tissue development, cell differentiation, and survival. Nevertheless, the role of autophagy in tooth development has not been definitively identified. The goal of this study was to investigate how autophagy is involved in midkine (MK)-mediated odontoblast-like differentiation, mineralization, and tertiary dentin formation in a mouse tooth pulp exposure model. In vitro studies show that MK and LC3 have similar expression patterns during odontoblast-like cell differentiation. Odontoblast-like cell differentiation is promoted through MK-mediated autophagy, which leads to increased mineralized nodule formation. Subcutaneous transplantation of hydroxyapatite/tricalcium phosphate with rMK-treated human dental pulp cells led to dentin pulp-like tissue formation through MK-mediated autophagy. Furthermore, MK-mediated autophagy induces differentiation of dental pulp cells into odontoblast-like cells that form DSP-positive tertiary dentin in vivo. Our findings may provide 1) novel insight into the role of MK in regulating odontoblast-like differentiation and dentin formation in particular via autophagy and 2) potential application of MK in vital pulp therapy.
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Development of Volumetric Independent Dose Calculation System for Verification of the Treatment Plan in Image-Guided Adaptive Brachytherapy. Front Oncol 2020; 10:609. [PMID: 32477931 PMCID: PMC7237701 DOI: 10.3389/fonc.2020.00609] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/03/2020] [Indexed: 11/30/2022] Open
Abstract
Purpose: This study aimed to develop a volumetric independent dose calculation (vIDC) system for verification of the treatment plan in image-guided adaptive brachytherapy (IGABT) and to evaluate the feasibility of the vIDC in clinical practice with simulated cases. Methods: The vIDC is based on the formalism of TG-43. Four simulated cases of cervical cancer were selected to retrospectively evaluate the dose distributions in IGABT. Some reference point doses, such as points A and B and rectal points, were calculated by vIDC using absolute coordinate. The 3D dose volume was also calculated to acquire dose-volume histograms (DVHs) with grid resolutions of 1.0 × 1.0 (G1.0), 2.5 × 2.5 (G2.5), and 0.5 × 0.5 mm2 (G0.5). Dosimetric parameters such as D90% and D2cc doses covering 90% of the high-risk critical target volume (HR-CTV) and 2 cc of the organs at risk (OARs) were obtained from DVHs. D90% also converted to equivalent dose in 2-Gy fractions (EQD2) to produce the same radiobiological effect as external beam radiotherapy. In addition, D90% was obtained in two types with or without the applicator volume to confirm the effect of the applicator itself. Validation of the vIDC was also performed using gamma evaluation by comparison with Monte Carlo simulation. Results: The average percentage difference of point doses was <2.28%. The DVHs for the HR-CTV and OARs showed no significant differences between the vIDC and the treatment planning system (TPS). Without considering the applicator volume, the D90% of the HR-CTV calculated by the vIDC decreases with a decreasing calculated dose-grid size (32.4, 5.65, and −2.20 cGy in G2.5, G1.0, and G0.5, respectively). The overall D90% is higher when considering the applicator volume. The converted D90% by EQD2 ranged from −1.29 to 1.00%. The D2cc of the OARs showed that the averaged dose deviation is <10 cGy regardless of the dose-grid size. Based on gamma analysis, the passing rate was 98.81% for 3%/3-mm criteria. Conclusion: The vIDC was developed as an independent dose verification system for verification of the treatment plan in IGABT. We confirmed that the vIDC is suitable for second-check dose validation of the TPS under various conditions.
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P1526Pre-dialysis left atrial function assessed by two-dimensional speckle tracking echocardiography as a predictor of upcoming heart failure in hemodialysis patients. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz748.0288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Left atrial global longitudinal strain (LA GLS) by 2-dimensional speckle tracking echocardiography is a useful tool to assess LA function and left ventricular (LV) diastolic function. The authors assessed prognostic value of LA GLS, and other diastolic functional parameters in patients undergoing hemodialysis.
Methods
A total of 78 (49 male) patients undergoing hemodialysis who checked echocardiography due to heart failure (HF) symptoms were included for this analysis. Echocardiography wasperformed at the same day of, and before hemodialysis session. Besides conventional echocardiographic measurements, GLS of the LA and the LV were checked and compared. Incidence of rehospitalization due to HF symptoms during mean follow up duration of 381.4±197.5 days was investigated and echocardiographic parameters were compared between patients who experienced rehospitalization and who did not.
Results
16 (20.1%) patients experienced rehospitalization due to HF. HF rehospitalization group had significantly low baseline LV ejection fraction (55.7±7.2 vs. 61.3±7.1%, p=0.006) and LV GLS (14.7±3.4 vs. 18.2±3.9%, p=0.002), while LV geometry (LV end-diastolic volume index and LV wall thickness) did not show significant differences. In HF rehospitalization group, baseline LA function and diastolic function were significantly impaired as reflected by LA GLS (18.8±2.6 vs. 23.8±3.6%, p<0.001), E/E' ratio (20.8±3.3 vs. 15.8±4.6%, p<0.001), and right ventricular systolic pressure (61.4±9.6 vs. 53.4±12.8%, p=0.022). LA end-systolic volume index was not significantly different between the 2 groups. Among various echocardiographic parameters, receiver operation characteristic curve analysis revealed that LA GLS had the strongest power (cutoff value 20.6%, sensitivity 0.813 and specificity 0.790, area under curve 0.849) in prediction of future rehospitalization due to HF.
Predictor of future HF: ROC analysis
Conclusions
The present study demonstrated that functional changes of the LA as measured by LA GLS before hemodialysis session can be used as an echocardiographic parameter to predict future rehospitalization due to HF. Further studies are required to evaluate prognostic value of LA function in predicting other cardiovascular events in hemodialysis patients.
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P688Cardiac dysfunction as a predictor of hepatic sinusoidal obstruction syndrome after hematopoietic cell transplantation. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Hepatic sinusoidal obstruction syndrome (HSOS) is a well-known fatal complication of hematopoietic cell transplantation (HCT), but the impact of cardiac abnormalities on the occurrence of HSOS has been poorly evaluated. Therefore, the authors investigated whether the structural changes or dysfunction of the heart before HCT is associated with the future occurrence of HSOS.
Methods
A total of 92 patients who underwent HCT were divided into 2 groups; HSOS group (n=11, 6 males, 53.8±15.9 years) vs no HSOS group (n=81, 51 males, 48.6±14.7 years). According to the modified Seattle criteria, HSOS was defined as otherwise unexplained occurrence of 2 or more of the following events within 20 days of HCT; serum total bilirubin >2 mg/dL, hepatomegaly or right upper quadrant pain, sudden weight gain due to fluid accumulation (>2% of baseline body weight). Echocardiography examinations were performed 1 month before HCT, and echocardiographic findings were compared between the groups.
Results
HSOS was developed in 11 patients (12.0%). HSOS group had significantly larger left ventricular end-diastolic volume index (LVEDVI) (65.2±4.9 vs 53.2±6.9 ml/m2, p<0.001) and relatively worse systolic function than no HSOS group (LV ejection fraction: 56.4±3.4 vs 65.1±5.9%, p<0.001, LV global longitudinal strain: −17.9±1.4 vs −20.1±2.0%, p=0.001). LV diastolic functional parameters were also significantly worse in HSOS group than in no HSOS group (E/E' ratio: 11.3±1.8 vs 9.1±2.0, p=0.002, left atrial global longitudinal strain: 27.7±3.3 vs 34.9±5.9%, p<0.001). However, left atrial volume index was not different between the groups (30.8±2.8 vs 29.0±3.3 ml/m2, p=0.078). By receiver operation characteristic curve analysis, among significantly different variables, LVEDVI was the most powerful predictor for HSOS, and the optimal cutoff value was 59.25 mL/m2. (81.8% sensitivity and 77.8% specificity, AUC 0.909).
Predictor of HSOS: ROC analysis
Conclusions
The present study demonstrated that structural changes or dysfunction of the heart are more prevalent in patients with HSOS after HCT and larger LVEDVI, among them, can be a useful predictor of upcoming HSOS. Routine echocardiographic study before HCT would be useful to identify high risk group for HSOS, and the development of HSOS should be carefully monitored in HCT patients with cardiac structural changes or dysfunction on echocardiography.
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P671Impacts of echocardiography-defined pulmonary hypertension on clinical outcome in patients with multiple myeloma. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Pulmonary hypertension (PH) is a rarely reported complication of multiple myeloma (MM). PH of MM is usually mild to moderate and can be secondary to a variety of conditions, including left ventricular dysfunction, diastolic dysfunction, chronic heart failure, treatment-related toxicity, thrombophilic condition and precapillary involvement. However, only few reports regarding PH in MM incidence and prognosis exist up to now.
Purpose
The purpose of this study was to investigate the risk factors of transthoracic echocardiography-defined PH and its impact on clinical outcome in patients with MM.
Methods
A total of 277 MM patients was included and divided into 2 groups–those non-pulmonary hypertension (PH) or those with PH, based on the results of the transthoracic echocardiography (TTE); PH group (n=143, 60.9±9.2 years, 68 males) versus non-PH group (n=134, 55.9±11.5 years, 72 males). We analyzed propensity score matching and multiple imputation method were used to deal with the missing data in echocardiographic characteristics.
Results
During the follow-up period (median 618 days), all-cause death occurred in 79 (28.5%) patients and 41 patients (14.8%) died from cardiovascular causes (including acute decompensated heart failure, fatal MI, sudden cardiac arrest). In the Kaplan-Meier survival analysis of crude population and propensity-matched population, cumulative overall survival and cardiovascular death (CVD)-free survival were significantly lower in the PH group than in the non-PH group (p<0.001). In propensity-matched population, estimated pulmonary artery pressure >35mmHg in TTE, congestive heart failure, and DM were significant independent predictors of all-cause death.
KM curves in MM stratified by PH
Conclusion
This study demonstrates that the presence of PH, congestive heart failure, and DM is an independent prognostic factor for all-cause death in MM patients with MM. These results highlight the risk associated cardiovascular disease in MM patients and emphasize that management strategies that prevent deterioration of cardiac function are essential.
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Technical Note: Real‐time 3D MRI in the presence of motion for MRI‐guided radiotherapy: 3D Dynamic keyhole imaging with super‐resolution. Med Phys 2019; 46:4631-4638. [DOI: 10.1002/mp.13748] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/21/2019] [Accepted: 07/22/2019] [Indexed: 12/11/2022] Open
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Synthetic CT reconstruction using a deep spatial pyramid convolutional framework for MR‐only breast radiotherapy. Med Phys 2019; 46:4135-4147. [DOI: 10.1002/mp.13716] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/14/2019] [Accepted: 07/03/2019] [Indexed: 12/31/2022] Open
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Immunotherapeutic strategies for cutaneous squamous cell carcinoma prevention in xeroderma pigmentosum. Br J Dermatol 2019; 181:1095-1097. [PMID: 31102460 DOI: 10.1111/bjd.18144] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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MRI super‐resolution reconstruction for MRI‐guided adaptive radiotherapy using cascaded deep learning: In the presence of limited training data and unknown translation model. Med Phys 2019; 46:4148-4164. [DOI: 10.1002/mp.13717] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 06/14/2019] [Accepted: 07/07/2019] [Indexed: 11/06/2022] Open
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Characterization of a prototype rapid kilovoltage x-ray image guidance system designed for a ring shape radiation therapy unit. Med Phys 2019; 46:1355-1370. [PMID: 30675902 DOI: 10.1002/mp.13396] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/03/2018] [Accepted: 12/21/2018] [Indexed: 01/15/2023] Open
Abstract
PURPOSE This study aims to characterize the performance of a prototype rapid kilovoltage (kV) x-ray image guidance system onboard the newly released Halcyon 2.0 linear accelerator (Varian Medical Systems, Palo Alto, CA) by use of conventional and innovatively designed testing procedures. METHODS Basic imaging system performance tests and radiation dose measurements were performed for all eleven kV-cone beam computed tomography (CBCT) imaging protocols available on a preclinical Halcyon 2.0 LINAC. Both conventional CBCT reconstruction using the Feldkamp-Davis-Kress (FDK) algorithm and a novel, advanced iterative reconstruction (iCBCT) available on this platform were evaluated. Standard image quality metrics, including slice thickness accuracy, high-contrast resolution, low-contrast resolution, regional uniformity and noise, and CT Hounsfield unit (HU) number accuracy and linearity were evaluated using a manufacturer-supplied QUART phantom (GmbH, Zorneding, Germany) and an independent image quality phantom (Catphan 500, The Phantom Laboratory, New York, NY). Due to the simplified design of the QUART phantom, we developed surrogate and clinically feasible strategies for measuring slice thickness and high- and low-contrast resolution. Imaging dose delivered by these eleven protocols was measured using a computed tomography dose index phantom and pencil chamber with commonly accepted methods and procedures. A subset of measurements were repeated on a conventional C-arm LINAC (TrueBeam and Trilogy, Varian Medical System) for comparison. Clinical patient images of pelvic and abdominal regions are also presented for qualitative assessment as part of a feasibility study for clinical implementation. RESULTS Image acquisition time was 17-42 s on the Halcyon system compared with 60 s on the C-arm LINAC systems. The kV imager projection offset, imaging and treatment isocenter coincidence and the couch three-dimensional match movement all achieved less than1 mm mechanical accuracy. All major image quality metrics were within either the national guideline or vendor-recommended tolerances. The designed surrogate approach with the QUART phantom showed a range of 0.24-0.35 cycles/mm for spatial resolution, a contrast-to-noise ratio (CNR) of 2-20 for FDK reconstruction and a tolerance of 0.5 mm for slice thickness. Other metrics derived from the Catphan images obtained on the Halcyon and C-arm LINACs showed comparable values for the FDK reconstruction. The iterative reconstruction tended to reduce noise, as evidenced by a higher CNR ratio. The fast scan pelvis protocols for Halcyon resulted in 50% lower dose compared to the standard scans, and the thorax fast protocol similarly delivered 10% lower dose than the standard thoracic scan. Preliminary patient images indicated that rapid kV CBCT with breath-hold is feasible, with improved imaging quality compared to free-breathing scans. CONCLUSION Independent and comprehensive characterization of the kV imaging guidance system on the Halcyon 2.0 system demonstrated acceptable image quality for clinical use. The imaging unit onboard the Halcyon meets vendor specifications and satisfies requirements for routine clinical use. The fast kV imaging system enables the potential for volumetric CBCT acquisition during a single breath-hold and the iterative reconstruction tends to reduce the noise therefore has the potential to improve the CNR for normal size patient.
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469Optimal timing of extracorporeal membrane oxygenation in patients with acute myocardial infarction complicated by profound cardiogenic shock after resuscitated cardiac arrest. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy564.469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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P3506The impacts of cancer staging on cardiac function in multiple myeloma. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy563.p3506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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6135Left atrial global longitudinal strain as a new predictor of cardiotoxicity in breast cancer patients. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy566.6135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Optimization of treatment planning workflow and tumor coverage during daily adaptive magnetic resonance image guided radiation therapy (MR-IGRT) of pancreatic cancer. Radiat Oncol 2018; 13:51. [PMID: 29573744 PMCID: PMC5866525 DOI: 10.1186/s13014-018-1000-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 03/15/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND To simplify the adaptive treatment planning workflow while achieving the optimal tumor-dose coverage in pancreatic cancer patients undergoing daily adaptive magnetic resonance image guided radiation therapy (MR-IGRT). METHODS In daily adaptive MR-IGRT, the plan objective function constructed during simulation is used for plan re-optimization throughout the course of treatment. In this study, we have constructed the initial objective functions using two methods for 16 pancreatic cancer patients treated with the ViewRay™ MR-IGRT system: 1) the conventional method that handles the stomach, duodenum, small bowel, and large bowel as separate organs at risk (OARs) and 2) the OAR grouping method. Using OAR grouping, a combined OAR structure that encompasses the portions of these four primary OARs within 3 cm of the planning target volume (PTV) is created. OAR grouping simulation plans were optimized such that the target coverage was comparable to the clinical simulation plan constructed in the conventional manner. In both cases, the initial objective function was then applied to each successive treatment fraction and the plan was re-optimized based on the patient's daily anatomy. OAR grouping plans were compared to conventional plans at each fraction in terms of coverage of the PTV and the optimized PTV (PTV OPT), which is the result of the subtraction of overlapping OAR volumes with an additional margin from the PTV. RESULTS Plan performance was enhanced across a majority of fractions using OAR grouping. The percentage of the volume of the PTV covered by 95% of the prescribed dose (D95) was improved by an average of 3.87 ± 4.29% while D95 coverage of the PTV OPT increased by 3.98 ± 4.97%. Finally, D100 coverage of the PTV demonstrated an average increase of 6.47 ± 7.16% and a maximum improvement of 20.19%. CONCLUSIONS In this study, our proposed OAR grouping plans generally outperformed conventional plans, especially when the conventional simulation plan favored or disregarded an OAR through the assignment of distinct weighting parameters relative to the other critical structures. OAR grouping simplifies the MR-IGRT adaptive treatment planning workflow at simulation while demonstrating improved coverage compared to delivered pancreatic cancer treatment plans in daily adaptive radiation therapy.
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Variable step size methods for solving simultaneous algebraic reconstruction technique (SART)-type cbct reconstructions. Oncotarget 2018; 8:33827-33835. [PMID: 28476047 PMCID: PMC5464914 DOI: 10.18632/oncotarget.17385] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/20/2017] [Indexed: 11/25/2022] Open
Abstract
Compared to analytical reconstruction by Feldkamp-Davis-Kress (FDK), simultaneous algebraic reconstruction technique (SART) offers a higher degree of flexibility in input measurements and often produces superior quality images. Due to the iterative nature of the algorithm, however, SART requires intense computations which have prevented its use in clinical practice. In this paper, we developed a fast-converging SART-type algorithm and showed its clinical feasibility in CBCT reconstructions. Inspired by the quasi-orthogonal nature of the x-ray projections in CBCT, we implement a simple yet much faster algorithm by computing Barzilai and Borwein step size at each iteration. We applied this variable step-size (VS)-SART algorithm to numerical and physical phantoms as well as cancer patients for reconstruction. By connecting the SART algebraic problem to the statistical weighted least squares problem, we enhanced the reconstruction speed significantly (i.e., less number of iterations). We further accelerated the reconstruction speed of algorithms by using the parallel computing power of GPU.
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Genetic driver mutations define the expression signature and microenvironmental composition of high-grade gliomas. Glia 2017; 65:1914-1926. [PMID: 28836293 DOI: 10.1002/glia.23203] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 07/24/2017] [Accepted: 07/27/2017] [Indexed: 11/11/2022]
Abstract
High-grade gliomas (HGG), including glioblastomas, are characterized by invasive growth, resistance to therapy, and high inter- and intra-tumoral heterogeneity. The key histological hallmarks of glioblastoma are pseudopalisading necrosis and microvascular proliferation, which allow pathologists to distinguish glioblastoma from lower-grade gliomas. In addition to being genetically and molecularly heterogeneous, HGG are also heterogeneous with respect to the composition of their microenvironment. The question of whether this microenvironmental heterogeneity is driven by the molecular identity of the tumor remains controversial. However, this question is of utmost importance since microenvironmental, non-neoplastic cells are key components of the most radiotherapy- and chemotherapy-resistant niches of the tumor. Our work demonstrates a versatile, reliable, and reproducible adult HGG mouse model with NF1-silencing as a driver mutation. This model shows significant differences in tumor microenvironment, expression of subtype-specific markers, and response to standard therapy when compared to our established PDGFB-overexpressing HGG mouse model. PDGFB-overexpressing and NF1-silenced murine tumors closely cluster with human proneural and mesenchymal subtypes, as well as PDGFRA-amplified and NF1-deleted/mutant human tumors, respectively, at both the RNA and protein expression levels. These models can be generated in fully immunocompetent mixed or C57BL/6 genetic background mice, and therefore can easily be incorporated into preclinical studies for cancer cell-specific or immune cell-targeting drug discovery studies.
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Development of a fast Monte Carlo dose calculation system for online adaptive radiation therapy quality assurance. Phys Med Biol 2017; 62:4970-4990. [DOI: 10.1088/1361-6560/aa6e38] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Angular under-sampling effect on VMAT dose calculation: An analysis and a solution strategy. Med Phys 2017; 44:2096-2114. [PMID: 28370002 DOI: 10.1002/mp.12250] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 02/22/2017] [Accepted: 03/24/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Most VMAT algorithms compute the dose on discretized apertures with small angular separations for practical reasons. However, machines deliver the VMAT dose with a continuously moving MLC and gantry and a continuously changing dose rate. The computed dose can deviate from the delivered dose, especially if no, or loose, MLC movement constraints are applied for the VMAT optimization. The goal of this paper is to establish a simplified mathematical model to analyze the discrepancy between the VMAT plan calculation dose and the delivered dose and to provide a reasonable solution for clinical implementation. METHODS A simplified metric is first introduced to describe the discrepancy between doses computed with discretized apertures and a continuous delivery model. The delivery fluences were formed separately for six different leaf movement scenarios. The formula was then rewritten in a more general form. The correlation between discretized and continuous fluence is summarized using this general form. The Fourier analysis for the impacts from three separate factors - dose kernel width, aperture width, aperture distance - to the dose discrepancy is also presented in order to provide insight into the dose discrepancy caused by under-sampling in the frequency domain. Finally, a weighting-based interpolation (WBI) algorithm, which can improve the aperture interpolation efficiency, is proposed. The associated evaluation methods and criteria for the proposed algorithm are also given. RESULTS The comparisons between the WBI algorithm and the equal angular interpolation (EAI) method suggested that the proposed algorithm has a great advantage with regard to aperture number efficiency. To achieve a 90% gamma passing rate using the dose computed with apertures generated with 0.5° EAI, with the initial optimization apertures as the standard for the comparison, the WBI needs only 66% and 54% of the aperture numbers that the EAI method needs for a 2° and a 4° angular separation of the VMAT optimization, respectively. The results also suggested that the weighted dose error index value, Θ, can be used as a stopping criterion for an interpolation algorithm, e.g., WBI or EAI, or as an indicator for sampling level evaluations. The phantom results indicate that the gamma passing rate decreases with increasing depth, from the phantom surface to the iso center, for the plans computed with under-sampled apertures. No obvious variation trends were observed for the plans computed with well-sampled apertures. CONCLUSIONS The mathematical analysis suggests that the dose discrepancies due to under-sampling are strongly correlated with the aperture width, the distance between apertures, and the width of the dose kernel. The WBI algorithm proves to be an efficient aperture interpolation strategy and is useful for dose computation of VMAT plans.
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Optimization of Proton CT Detector System and Image Reconstruction Algorithm for On-Line Proton Therapy. PLoS One 2016; 11:e0156226. [PMID: 27243822 PMCID: PMC4886974 DOI: 10.1371/journal.pone.0156226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 05/11/2016] [Indexed: 11/24/2022] Open
Abstract
The purposes of this study were to optimize a proton computed tomography system (pCT) for proton range verification and to confirm the pCT image reconstruction algorithm based on projection images generated with optimized parameters. For this purpose, we developed a new pCT scanner using the Geometry and Tracking (GEANT) 4.9.6 simulation toolkit. GEANT4 simulations were performed to optimize the geometric parameters representing the detector thickness and the distance between the detectors for pCT. The system consisted of four silicon strip detectors for particle tracking and a calorimeter to measure the residual energies of the individual protons. The optimized pCT system design was then adjusted to ensure that the solution to a CS-based convex optimization problem would converge to yield the desired pCT images after a reasonable number of iterative corrections. In particular, we used a total variation-based formulation that has been useful in exploiting prior knowledge about the minimal variations of proton attenuation characteristics in the human body. Examinations performed using our CS algorithm showed that high-quality pCT images could be reconstructed using sets of 72 projections within 20 iterations and without any streaks or noise, which can be caused by under-sampling and proton starvation. Moreover, the images yielded by this CS algorithm were found to be of higher quality than those obtained using other reconstruction algorithms. The optimized pCT scanner system demonstrated the potential to perform high-quality pCT during on-line image-guided proton therapy, without increasing the imaging dose, by applying our CS based proton CT reconstruction algorithm. Further, we make our optimized detector system and CS-based proton CT reconstruction algorithm potentially useful in on-line proton therapy.
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Self-expandable metal stents for malignant esophageal obstruction: a comparative study between extrinsic and intrinsic compression. Dis Esophagus 2016; 29:224-8. [PMID: 25708695 DOI: 10.1111/dote.12325] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Self-expandable metal stents (SEMSs) are effective for malignant esophageal obstruction, but usefulness of SEMSs in extrinsic lesions is yet to be elucidated. This study is aimed at evaluating the clinical usefulness of SEMSs in the extrinsic compression compared with intrinsic. A retrospective review was conducted for 105 patients (intrinsic, 85; extrinsic, 20) with malignant esophageal obstruction who underwent endoscopic SEMSs placement. Technical and clinical success rates were evaluated and clinical outcomes were compared between extrinsic and intrinsic group. Extrinsic group was mostly pulmonary origin. Overall technical and clinical success rate was 100% and 91%, respectively, without immediate complications. Extrinsic and intrinsic group did not differ significantly in clinical success rate. The median stent patency time was 131.3 ± 85.8 days in intrinsic group while that of extrinsic was 54.6 ± 45.1 due to shorter survival after stent insertion. The 4-, 8-, and 12-week patency rates were 90.5%, 78.8%, and 64.9% respectively in intrinsic group, while stents of extrinsic group remained patent until death. Uncovered, fully covered, and double-layered stent were used evenly and the types did not influence patency in both groups. In conclusion, esophageal SEMSs can safely and effectively be used for malignant extrinsic compression as well as intrinsic.
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Poster session 3The imaging examinationP646Simulator-based testing of skill in transthoracic echoP647Clinical and echocardiographic characteristics of isolated left ventricular non-compactionP648Appropriate use criteria of transthoracic echocardiography and its clinical impact in an aged populationAnatomy and physiology of the heart and great vesselsP649Prevalence and determinants of exercise oscillatory ventilation in the EUROEX trial populationAssessment of diameters, volumes and massP650Left atrial remodeling after percutaneous left atrial appendage closureP651Global atrial performance with tyrosine kinase inhibitors in metastatic renal cell carcinomaP652Early right ventricular response to cardiac resynchronization therapy: impact on clinical outcomesP653Parameters of speckle-tracking echocardiography and biomechanical values of a dilative ascending aortaAssessments of haemodynamicsP654Right atrial hemodynamics in infants and children: observations from 3-dimensional echocardiography derived right atrial volumesAssessment of systolic functionP655One-point carotid wave intensity predicts cardiac mortality in patients with congestive heart failure and reduced ejection fractionP656Persistence of cardiac remodeling in adolescents with previous fetal growth restrictionP6572D speckle tracking-derived left ventricle global longitudinal strain and left ventricular dysfunction stages: a useful discriminator in moderate-to-severe aortic regurgitationP658Global longitudinal strain and strain rate in type two diabetes patients with chronic heart failure: relevance to circulating osteoprotegerinP659Analysis of left ventricular function in patients before and after surgical and interventional mitral valve therapyP660Left ventricular end-diastolic volume is complementary with global longitudinal strain for the prediction of left ventricular ejection fraction in echocardiographic daily practiceP661Left ventricular assist device, right ventricle function, and selection bias: the light side of the moonP662Assessment of right ventricular function in patients with anterior ST elevation myocardial infarction; a 2-d speckle tracking studyP663Right ventricular systolic function assessment in sickle cell anaemia using echocardiographyAssessment of diastolic functionP664Prognostic value of transthoracic cardiopulmonary ultrasound in cardiac surgery intensive care unitP665Comparative efficacy of renin-angiotensin system modulators on prognosis, right heart and left atrial parameters in patients with chronic heart failure and preserved left ventricular systolic functionP666Left atrial volume index is the most significant diastolic functional parameter of hemodynamic burden as measured by NT-proBNP in acute myocardial infarctionP667Preventive echocardiographic screening. preliminary dataP668Assessment of the atrial electromechanical delay and the mechanical functions of the left atrium in patients with diabetes mellitus type IIschemic heart diseaseP669Coronary flow velocity reserve by echocardiography as a measure of microvascular function: feasibility, reproducibility and agreement with PET in overweight patients with coronary artery diseaseP670Influence of cardiovascular risk in the occurrence of events in patients with negative stress echocardiographyP671Prevalence of transmural myocardial infarction and viable myocardium in chronic total occlusion (CTO) patientsP672The impact of the interleukin 6 receptor antagonist tocilizumab on mircovascular dysfunction after non st elevation myocardial infarction assessed by coronary flow reserve from a randomized studyP673Impact of manual thrombus aspiration on left ventricular remodeling: the echocardiographic substudy of the randomized Physiologic Assessment of Thrombus Aspirtion in patients with ST-segment ElevatioP674Acute heart failure in STEMI patients treated with primary percutaneous coronary intervention is related to transmural circumferential myocardial strainP675Long-term prognostic value of infarct size as assessed by cardiac magnetic resonance imaging after a first st-segment elevation myocardial infarctionHeart valve DiseasesP676Prognostic value of LV global longitudinal strain in aortic stenosis with preserved LV ejection fractionP677Importance of longitudinal dyssynchrony in low flow low gradient severe aortic stenosis patients undergoing dobutamine stress echocardiography. a multicenter study (on behalf of the HAVEC group)P678Predictive value of left ventricular longitudinal strain by 2D Speckle Tracking echocardiography, in asymptomatic patients with severe aortic stenosis and preserved ejection fractionP679Clinical and echocardiographic characteristics of the flow-gradient patterns in patients with severe aortic stenosis and preserved left ventricular ejection fractionP6802D and 3D speckle tracking assessment of left ventricular function in severe aortic stenosis, a step further from biplane ejection fractionP681Functional evaluation in aortic stenosis: determinant of exercise capacityP682Left ventricular mechanics: novel tools to evaluate left ventricular function in patients with primary mitral regurgitationP683Plasma B-type natriuretic peptide level in patients with isolated rheumatic mitral stenosisP684Quantitative assessment of severity in aortic regurgitation and the influence of elastic proprieties of thoracic aortaP685Characterization of chronic aortic and mitral regurgitation using cardiovascular magnetic resonanceP686Functional mitral regurgitation: a warning sign of underlying left ventricular systolic dysfunction in heart failure with preserved ejection fraction.P687Secondary mitral valve tenting in primary degenerative prolapse quantified by three-dimensional echocardiography predicts regurgitation recurrence after mitral valve repairP688Advanced heart failure with reduced ejection fraction and severe mitral insufficiency compensate with a higher oxygen peripheral extraction to a reduced cardiac output vs oxygen uptake response to maxP689Predictors of acute procedural success after percutaneous mitraclip implantation in patients with moderate-to-severe or severe mitral regurgitation and reduced ejection fractionP690The value of transvalvular gradients obtained by transthoracic echocardiography in estimation of severe paravalvular leakage in patients with mitral prosthetic valvesP691Characteristics of infective endocarditis in a non tertiary hospitalP692Infective endocarditis: predictors of severity in a 3-year retrospective analysisP693New echocardiographic predictors of early recurrent mitral functional regurgitation after mitraclip implantationP694Transesophageal echocardiography can be reliably used for the allocation of patients with severe aortic stenosis for tras-catheter aortic valve implantationP695Annular sizing for transcatheter aortic valve selection. A comparison between computed tomography and 3D echocardiographyP696Association between aortic dilatation, mitral valve prolapse and atrial septal aneurysm: first descriptive study.CardiomyopathiesP698Cardiac resynchronization therapy by multipoint pacing improves the acute response of left ventricular mechanics and fluid dynamics: a three-dimensional and particle image velocimetry echo studyP699Long-term natural history of right ventricular function in dilated cardiomyopathy: innocent bystander or leading actor?P700Right to left ventricular interdependence at rest and during exercise assessed by the ratio between pulmonary systolic to diastolic time in heart failure reduced ejection fractionP701Exercise strain imaging demonstrates impaired right ventricular contractile reserve in patients with hypertrophic cardiomyopathyP702Prevalence of overt left ventricular dysfunction (burn-out phase) in a portuguese population of hypertrophic cardiomyopathy, a multicentre studyP703Systolic and diastolic myocardial mechanics in hypertrophic cardiomyopathy and their link to the extent of hypertrophy, replacement fibrosis and interstitial fibrosisP704Multimodality imaging and genotype-phenotype associations in a cohort of patients with hypertrophic cardiomyopathy studied by next generation sequencing and cardiac magnetic resonanceP705Sudden cardiac death risk assessment in apical hypertrophic cardiomyopathy: do we need to add MRI to the equation?P706Prognostic value of left ventricular ejection fraction, proBNP, exercise capacity, and NYHA functional class in patients with left ventricular non-compaction cardiomyopathyP707The anti-hypertrophic microRNAs miR-1, miR-133a and miR-26b and their relationship to left ventricular hypertrophy in patients with essential hypertensionP708Prevalence of left ventricular systolic dysfunction in a portuguese population of left ventricular non-compaction cardiomyopathy, a multicentre studyP709Assessment of systolic and diastolic features in light chain amyloidosis: an echocardiographic and cardiac magnetic resonance studyP710Morbid obesity-associated hypertension identifies bariatric surgery best responders: Clinical and echocardiographic follow up studyP711Echocardiographic markera for overhydration in patients under haemodialysisP712Gender aspects of right ventricular size and function in clinically stable heart transplant patientsP713Evidence of cardiac stem cells from the left ventricular apical tip in patients undergone LVAD implant: a comparative strain-ultrastructural studySystemic diseases and other conditionsP714Speckle tracking assessment of right ventricular function is superior for differentiation of pressure versus volume overloaded right ventricleP715Prognostic value of pulmonary arterial pressure: analysis in a large dataset of timely matched non-invasive and invasive assessmentsP716Effect of the glucagon-like peptide-1 analogue liraglutide on left ventricular diastolic and systolic function in patients with type 2 diabetes: a randomised, single-blinded, crossover pilot studyP717Tissue doppler evaluation of left ventricular functions, left atrial mechanical functions and atrial electromechanical delay in juvenile idiopathic arthritisP718Echocardiographic detection of subclinical left ventricular dysfunction in patients with rheumatoid arthritisP719Left ventricular strain values are unaffected by intense training: a longitudinal, speckle-tracking studyP720Diastolic left ventricular function in autosomal dominant polycystic kidney disease: a matched-cohort, speckle-tracking echocardiographic studyP721Relationship between adiponectin level and left ventricular mass and functionP722Left atrial function is impaired in patients with multiple sclerosisMasses, tumors and sources of embolismP723Paradoxical embolization to the brain in patients with acute pulmonary embolism and confirmed patent foramen ovale with bidirectional shunt, results of prospective monitoringP724Following the European Society of Cardiology proposed echocardiographic algorithm in elective patients with clinical suspicion of infective endocarditis: diagnostic yield and prognostic implicationsP725Metastatic cardiac18F-FDG uptake in patients with malignancy: comparison with echocardiographic findingsDiseases of the aortaP726Echocardiographic measurements of aortic pulse wave velocity correlate well with invasive methodP727Assessment of increase in aortic and carotid intimal medial thickness in adolescent type 1 diabetic patientsStress echocardiographyP728Determinants and prognostic significance of heart rate variability in renal transplant candidates undergoing dobutamine stress echocardiographyP729Pattern of cardiac output vs O2 uptake ratio during maximal exercise in heart failure with reduced ejection fraction: pathophysiological insightsP730Prognostic value and predictive factors of cardiac events in patients with normal exercise echocardiographyP731Right ventricular mechanics during exercise echocardiography: normal values, feasibility and reproducibility of conventional and new right ventricular function parametersP732The added value of exercise-echo in heart failure patients: assessing dynamic changes in extravascular lung waterP733Applicability of appropriate use criteria of exercise stress echocardiography in real-life practice: what have we improved with new documents?Transesophageal echocardiographyP7343D-TEE guidance in percutaneous mitral valve interventions correcting mitral regurgitationContrast echocardiographyP735Pulmonary transit time by contrast enhanced ultrasound as parameter for cardiac performance: a comparison with magnetic resonance imaging and NT-ProBNPReal-time three-dimensional TEEP736Optimal parameter selection for anisotropic diffusion denoising filters applied to aortic valve 4d echocardiographsP737Left ventricle systolic function in non-alcoholic cirrhotic candidates for liver transplantation: a three-dimensional speckle-tracking echocardiography studyTissue Doppler and speckle trackingP738Optimizing speckle tracking echocardiography strain measurements in infants: an in-vitro phantom studyP739Usefulness of vascular mechanics in aortic degenerative valve disease to estimate prognosis: a two dimensional speckle tracking studyP740Vascular mechanics in aortic degenerative valve disease: a two dimensional speckle-tracking echocardiography studyP741Statins and vascular load in aortic valve disease patients, a speckle tracking echocardiography studyP742Is Left Bundle Branch Block only an electrocardiographic abnormality? Study of LV function by 2D speckle tracking in patients with normal ejection fractionP743Dominant inheritance of global longitudinal strain in a population of healthy and hypertensive twinsP744Mechanical differences of left atria in paroxysmal atrial fibrillation: A speckle-tracking study.P745Different distribution of myocardial deformation between hypertrophic cardiomyopathy and aortic stenosisP746Left atrial mechanics in patients with chronic renal failure. Incremental value for atrial fibrillation predictionP747Subclinical myocardial dysfunction in cancer patients: is there a direct effect of tumour growth?P748The abnormal global longitudinal strain predicts significant circumflex artery disease in low risk acute coronary syndromeP7493D-Speckle tracking echocardiography for assessing ventricular funcion and infarct size in young patients after acute coronary syndromeP750Evaluation of left ventricular dyssynchrony by echocardiograhy in patients with type 2 diabetes mellitus without clinically evident cardiac diseaseP751Differences in myocardial function between peritoneal dialysis and hemodialysis patients: insights from speckle tracking echoP752Appraisal of left atrium changes in hypertensive heart disease: insights from a speckle tracking studyP753Left ventricular rotational behavior in hypertensive patients: Two dimensional speckle tracking imaging studyComputed Tomography & Nuclear CardiologyP754Effectiveness of adaptive statistical iterative reconstruction of 64-slice dual-energy ct pulmonary angiography in the patients with reduced iodine load: comparison with standard ct pulmonary angiograP755Clinical prediction model to inconclusive result assessed by coronary computed tomography angiography. Eur Heart J Cardiovasc Imaging 2015. [DOI: 10.1093/ehjci/jev277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Moderated Posters session: diastolic function in clinical perspectiveP1260Coronary flow reserve in patients with chest pain but without significant coronary stenosis: the role of hypertensionP1261Diastolic bicycle exercise: normal reference values and determinantsP1262Prediction of left ventricular diastolic dysfunction in breast cancer patients after chemotherapyP1263Impaired diastolic recovery is associated with adverse events in the patients with hypertensive heart failureP1264Diastolic strain parameters in hypertensive heart disease: Insights from a speckle tracking imagingP1265Standard echocardiographic parameters to assess right ventricular diastolic function does not detect increased end diastolic right ventricular pressure in pulmonary vascular diseaseP1266In heart failure with preserved ejection fraction carotid arterial stiffness is increased and may contribute to reduced functional reserveP1267Study of left atrial function by speckle tracking in young Egyptian females with unexplained dyspnea; pilot reportP1268stress effect on diastolic functionP1269Diastolic function and adjusted diastolic index in apparently healthy obese patients. Eur Heart J Cardiovasc Imaging 2015. [DOI: 10.1093/ehjci/jev271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Poster session 5The imaging examinationP1097Correlation between visual and quantitative assessment of left ventricle: intra- and inter-observer agreementP1099Incremental prognostic value of late gadolinium-enhanced by cardiac magnetic resonance in patients with heart failureAnatomy and physiology of the heart and great vesselsP1100Left ventricular geometry and diastolic performance in erectile dysfunction patients; a topic of differential arterial stiffness influenceAssessment of diameters, volumes and massP1101Impact of the percutaneous closure of atrial septal defect on the right heart "remodeling"P1102Left Ventricular Mass Indexation in Infants, Children and Adolescents: a Simplified Approach for the Identification of Left Ventricular Hypertrophy in Clinical PracticeP1103Impact of trabecules while quantifying cardiac magnetic resonance exams in patients with systemic right ventricleP1104Detection of subclinical atherosclerosis by carotid intima-media thickness: correlation with leukocytes telomere shorteningAssessments of haemodynamicsP1105Flow redirection towards the left ventricular outflow tract: vortex formation is not affected by variations in atrio-ventricular delayAssessment of systolic functionP1106Reproducibility and feasibility of cardiac MRI feature tracking in Fabry diseaseP1107Normal left ventricular strain values by two-dimensional strain echocardiography; result of normal (normal echocardiographic dimensions and functions in korean people) studyP1108Test-retest repeatability of global strain following st-elevation myocardial infarction - a comparison of tagging and feature trackingP1109Cardiotoxicity induced by tyrosine kinase inhibitors in patients with gastrointestinal stromal tumors (GIST)P1110Finite strain ellipses for the analysis of left ventricular principal strain directions using 3d speckle tracking echocardiographyP1111Antihypertensive therapy reduces time to peak longitudinal strainP1112Right ventricular systolic function as a marker of prognosis after inferior myocardial infarction - 5-year follow-upP1113Is artery pulmonary dilatation related with right but also early left ventricle dysfunction in pulmonary artery hypertension?P1114Right ventricular mechanics changes according to pressure overload increasing, a 2D-speckle tracking echocardiographic evaluationAssessment of diastolic functionP1115Paired comparison of left atrial strain from P-wave to P-wave and R-wave to R-waveP1116Diagnostic role of Tissue Doppler Imaging echocardiographic criteria in obese heart failure with preserved ejection fraction patientsP1117Evaluation of diastolic function of right ventricle in idiopathic pulmonary arterial hypertensionP1118Severity and predictors of diastolic dysfunction in a non-hypertensive non-ischemic cohort of Egyptian patients with documented systemic autoimmune disease; pilot reportP1119correlation between ST segment shift and cardiac diastolic function in patients with acute myocardial infarctionIschemic heart diseaseP1120Computed tomography coronary angiography verSus sTRess cArdiac magneTic rEsonance for the manaGement of sYmptomatic revascularized patients: a cost effectiveness study (STRATEGY study)P1121Utility of transmural myocardial mechanic for early infarct size prediction after primary percutaneous coronary intervention in STEMI patientsP1122Progressive Improvements of the echocardiographic deformation parameters in ST Elevation Myocardial Infarction after five years follow-upP1123Long-term prognostic value of left ventricular dyssynchrony as assessed by cardiac magnetic resonance feature-tracking imaging after a first st-segment elevation myocardial infarctionP1124Differences in mitral annulus remodeling in acute anterior ST elevation and acute inferior ST elevation myocardial infarctionP1125Reduction of microvascular injury using a novel theragnostic ultrasound strategy: a first in men feasibility and safety studyP1126Impact of focused echocardiography in clinical decision of patient presented with st elevation myocardial infarction underwent primary angioplastyHeart valve DiseasesP1127Aortic valve area calculation in aortic stenosis: a comparison among conventional and 3D-transesophageal echocardiography and computed tomographyP1128Myocardial fibrosis and microRNA-21 expression in patients with severe aortic valve stenosis and preserved ejection fraction: a 2D speckle tracking echocardiography, tissutal and plasmatic studyP1129Quantification of calcium amount in a new experimental model: a comparison between calibrated integrated backscatter of ultrasound and computed tomographyP1130Altered diffusion capacity in aortic stenosis: role of the right heartP1131Osteoprotegerin predicts all-cause mortality in calcific aortic stenosis patients with preserved left ventricle ejection fraction in long term observationP1132Mitral regurgitation as a risk factor for pulmonary hypertension in patients with aortic stenosisP1133The relationship between the level of plasma B-type natriuretic peptide and mitral stenosisP1134Aortic regurgitation, left ventricle mechanics and vascular load: a single centre 2d derived-speckle tracking studyP1135Feasibility and reproducibility issues limit the usefulness of quantitative colour Doppler parameters in the assessment of chronic aortic and mitral regurgitation severityP1136Predictors of postoperative outcome in degenerative mitral regurgitationP1137Left ventricular mechanical dyssynchrony in patients with severe mitral regurgitation of rheumatic etiology; three dimensional echocardiography studyP1138Functional mitral regurgitation and left atrial dysfunction concur in determining pulmonary hypertension and functional status in subjects with left ventricular systolic dysfunctionP11393D echocardiography allows more effective quantitative assessment of the severity of functional tricuspid regurgitation than conventional 2D/Doppler echocardiographyP1140Prosthetic valve thrombosis: still a severe disease? 10-years experience in a university hospitalP1141Validity of echocardiography in the hospital course of patients with feverP1142Do baseline 3DTEE characteristics of mitral valve apparatus predict long term result in patients undergoing percutaneous valve repair for degenerative regurgitation?P1143Influence of baseline aortic regurgitation on mitral regurgitation change after transcatheter aortic valve replacement for aortic stenosisP1144Prevalence of echocardiography detected significant valvular regurge in subclinical rheumatic carditis in assiut childrenCardiomyopathiesP1145Can we early detect left ventricular systolic dysfunction in patients with Duchenne muscular dystrophy using global longitudinal strain assessment?P1146Prevalence of isolated papillary muscle hypertrophy in young competitive athletesP1147Troponin release after exercise in patients with hypertrophic cardiomyopathy: associations with clinical and mr imaging characteristicsP1148Atrial fibrillation in hypertrophic cardiomyopathy: can we score the risk?P1149Impact of hypertrophy on multiple layer longitudinal deformation in hypertrophy cardiomyopathy and cardiac amyloidosis compared to controlsP1150Functional evaluation in hypertrophic cardiomyopathy combining cardiopulmonary exercise testing combined with exercise-echocardiographyP1151Refinement of the old diagnostic criteria of left ventricular noncompaction cardiomyopathy (LVNC) based on cardiac magnetic resonance (CMR)P1152Differences of clinical characteristics and outcomes between acute myocarditis with preserved and reduced left ventricular systolic functionP1153Value of longitudinal strain for distinguishing left ventricular non-compaction from idiopathic dilated cardiomyopathyP1154Speed of recovery of left ventricular function is not related to the prognosis of Takotsubo cardiomyopathy. A Portuguese multicentre studyP1155Predictors of in-hospital left ventricular systolic function recovery after admission with takotsubo cardiomyopathy. Portuguese multicentre studyP1156Mid-ventricular takotsubo detected by initial echocardiogram associates with recurrence of takotsubo cardiomyopathy - a portuguese multicentre studySystemic diseases and other conditionsP1157Relations between left ventricle remodelling and expression of angiotensin 2 AT2R1 geneP1158Impact of renal denervation on long-term blood pressure variability and surrogate markers of target organ damage in individuals with drug-resistant arterial hypertensionP1159Greater improvement of coronary artery function, left ventricular deformation and twisting by IL12/23 compared to TNF-a inhibition in psoriasisP1160Advanced glycation end products play a role in adverse LV remodeling following MIP1161Incidence of subclinical myocardial dysfunction in patients with systemic sclerosis and normal left ventricular systolic and diastolic functionP1162Left atrial remodeling and dysfunction occur early in patients with systemic sclerosis and normal left ventricular functionP1163Intrinsic vortex formation : a unique performance indicatorP1164P-wave morphology is unaffected by training-induced biatrial dilatation: a prospective, longitudinal study in healthy athletesP1165Usefulness of transthoracic echocardiography in diagnosis of young patients with ischemic strokeP1166Primary cardiac lymphoma: role of echocardiography in the clinical managementP1167Abnormal echocardiographic findings in cancer patients before chemotherapyMasses, tumors and sources of embolismP1168Three-dimensional transesophageal echocardiography of the left atrial appendage reduces rate of postpone electrical cardioversionP1169Detection of ventricular thrombus by cmr after reperfused st-segment elevation myocardial infarction correlated with echocardiographyP1170Clinical and transthoracic echocardiographic predictors of left atrial appendage thrombus in patients with atrial fibrillationStress echocardiographyP1171Pharmacological stress echocardiography complications: a 4-year single center experienceP1172Myocardial functional and perfusion reserve in type I diabetesP1173Feasibility of incorporating 3D Dobutamine stress echocardiography into routine clinical practiceP1174Right ventricular isovolumic acceleration at rest and during exercise in children after heart transplantP1175Right ventricular systolic and diastolic response to exercise in children after heart transplant -a bicycle exercise studyP1176Determinants of functional capacity in heart failure patients with reduced ejection fractionP1177Handgrip stress echocardiography with emotional component compared to conventional isometric exercise in coronary artery disease diagnosisP1178The relationship between resting transthoracic echocardiography and exercise capacity in patients with paroxysmal atrial fibrillationP1179Correlation between NT-proBNP and selected echocardiography parameters at rest and after exercise in patients with functional ischemic mitral regurgitation qualified for cardiosurgical treatmentReal-time three-dimensional TEEP1180Vena contracta area for severity grading in functional and degenerative mitral regurgitation: A study based on transesophageal 3D colour Doppler in 419 patientsP1181Proximal flow convergence by 3D echocardiography in the evaluation of mitral valve area in rheumatic mitral stenosisP1182Quantification of valve dimensions by transesophageal 3D echocardiography in patients with functional and degenerative mitral regurgitationTissue Doppler and speckle trackingP1183Automatic calculation of left ventricular volume changes over a cardiac cycle from echocardiography images by nonlinear dimensionality reductionP1184Effect of the mitral valve repairs on the left ventricular blood flow formationP1185Quantification of left atrial strain using cardiovascular magnetic resonance. a comparison between hypertrophic cardiomyopathy and healthy controlsP1186The role of early systolic lengthening in patients with non-ST elevation acute coronary syndrome and its relation to syntax scoreP1187Different standard two dimensional strain methods to quantity left ventricular mechanicsP1188Atrial function and electrocardiography caracteristics in sportsmen with or without paroxysmal atrial fibrillationP1189Right ventricular outflow premature contractions induce regional left ventricular dysfunctionP1190Ultrasound guided venous access for pacemaker and defibrillators. Randomized TrialP1191Atrial function analysis correlates with symptoms and quality of life of heart failure patientsP1192The use of tissue doppler echocardiography in myocardial iron overload in patients with thalassaemia majorP1193Independent association between pulse pressure and left ventricular global longitudinal strainP1194Global and regional longitudinal strain identifies the presence of coronary artery disease in patients with suspected reduction of coronary flow reserve and absence of wall motion abnormalitiesP1195Prognostic value of invasive and noninvasive parameters of right ventricular function in patients with pulmonary arterial hypertension receiving specific vasodilator therapyP1196Myocardial deformation analysis to improve arrhythmic risk stratificationP1197Quantitative assessment of regional systolic and diastolic function parameters for detecting prior transient ischemia in normokinetic segmentsP1198Left atrial function in patients with corrected tetralogy of Fallot - a three-dimensional speckle-tracking echocardiographic studyP1199Left atrial ejection force correlates with left atrial strain and volume-based functional properties as assessed by three-dimensional speckle tracking echocardiographyP1200Acute angulation of the aortic arch late after the arterial switch operation for transposition of the great arteries: impact on cardiac mechanicsP1201Circumferential deformation of the ascending thoracic aorta in hypertensive patients by three-dimensional speckle tracking echocardiographyCardiac Magnetic ResonanceP1202The incremental value of cardiac magnetic resonance on diagnosis myocardial infarction and non-obstructed coronary arteriesP1204Reference ranges of global and regional myocardial T1 values derived from MOLLI and shMOLLI at 3TComputed Tomography & Nuclear CardiologyP1205Deformation of the left atrial appendage after percutaneous closure with the Amplatzer cardiac plugP1206Prognostic impact of non-obstructive coronary artery disease on coronary computed tomographic angiography: A single-center study. Eur Heart J Cardiovasc Imaging 2015. [DOI: 10.1093/ehjci/jev275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Common-mask guided image reconstruction (c-MGIR) for enhanced 4D cone-beam computed tomography. Phys Med Biol 2015; 60:9157-83. [PMID: 26562284 DOI: 10.1088/0031-9155/60/23/9157] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Compared to 3D cone beam computed tomography (3D CBCT), the image quality of commercially available four-dimensional (4D) CBCT is severely impaired due to the insufficient amount of projection data available for each phase. Since the traditional Feldkamp-Davis-Kress (FDK)-based algorithm is infeasible for reconstructing high quality 4D CBCT images with limited projections, investigators had developed several compress-sensing (CS) based algorithms to improve image quality. The aim of this study is to develop a novel algorithm which can provide better image quality than the FDK and other CS based algorithms with limited projections. We named this algorithm 'the common mask guided image reconstruction' (c-MGIR).In c-MGIR, the unknown CBCT volume is mathematically modeled as a combination of phase-specific motion vectors and phase-independent static vectors. The common-mask matrix, which is the key concept behind the c-MGIR algorithm, separates the common static part across all phase images from the possible moving part in each phase image. The moving part and the static part of the volumes were then alternatively updated by solving two sub-minimization problems iteratively. As the novel mathematical transformation allows the static volume and moving volumes to be updated (during each iteration) with global projections and 'well' solved static volume respectively, the algorithm was able to reduce the noise and under-sampling artifact (an issue faced by other algorithms) to the maximum extent. To evaluate the performance of our proposed c-MGIR, we utilized imaging data from both numerical phantoms and a lung cancer patient. The qualities of the images reconstructed with c-MGIR were compared with (1) standard FDK algorithm, (2) conventional total variation (CTV) based algorithm, (3) prior image constrained compressed sensing (PICCS) algorithm, and (4) motion-map constrained image reconstruction (MCIR) algorithm, respectively. To improve the efficiency of the algorithm, the code was implemented with a graphic processing unit for parallel processing purposes.Root mean square error (RMSE) between the ground truth and reconstructed volumes of the numerical phantom were in the descending order of FDK, CTV, PICCS, MCIR, and c-MGIR for all phases. Specifically, the means and the standard deviations of the RMSE of FDK, CTV, PICCS, MCIR and c-MGIR for all phases were 42.64 ± 6.5%, 3.63 ± 0.83%, 1.31% ± 0.09%, 0.86% ± 0.11% and 0.52 % ± 0.02%, respectively. The image quality of the patient case also indicated the superiority of c-MGIR compared to other algorithms.The results indicated that clinically viable 4D CBCT images can be reconstructed while requiring no more projection data than a typical clinical 3D CBCT scan. This makes c-MGIR a potential online reconstruction algorithm for 4D CBCT, which can provide much better image quality than other available algorithms, while requiring less dose and potentially less scanning time.
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Image-domain shading correction for cone-beam CT without prior patient information. J Appl Clin Med Phys 2015; 16:65-75. [PMID: 26699555 PMCID: PMC5691004 DOI: 10.1120/jacmp.v16i6.5424] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 08/17/2015] [Accepted: 05/26/2015] [Indexed: 11/23/2022] Open
Abstract
In the era of high-precision radiotherapy, cone-beam CT (CBCT) is frequently utilized for on-board treatment guidance. However, CBCT images usually contain severe shading artifacts due to strong photon scatter from illumination of a large volume and non-optimized patient-specific data measurements, limiting the full clinical applications of CBCT. Many algorithms have been proposed to alleviate this problem by data correction on projections. Sophisticated methods have also been designed when prior patient information is available. Nevertheless, a standard, efficient, and effective approach with large applicability remains elusive for current clinical practice. In this work, we develop a novel algorithm for shading correction directly on CBCT images. Distinct from other image-domain correction methods, our approach does not rely on prior patient information or prior assumption of patient data. In CBCT, projection errors (mostly from scatter and non-ideal usage of bowtie filter) result in dominant low-frequency shading artifacts in image domain. In circular scan geometry, these artifacts often show global or local radial patterns. Hence, the raw CBCT images are first preprocessed into the polar coordinate system. Median filtering and polynomial fitting are applied on the transformed image to estimate the low-frequency shading artifacts (referred to as the bias field) angle-by-angle and slice-by-slice. The low-pass filtering process is done firstly along the angular direction and then the radial direction to preserve image contrast. The estimated bias field is then converted back to the Cartesian coordinate system, followed by 3D low-pass filtering to eliminate possible high-frequency components. The shading-corrected image is finally obtained as the uncorrected volume divided by the bias field. The proposed algorithm was evaluated on CBCT images of a pelvis patient and a head patient. Mean CT number values and spatial non-uniformity on the reconstructed images were used as image quality metrics. Within selected regions of interest, the average CT number error was reduced from around 300 HU to 42 and 38 HU, and the spatial nonuniformity error was reduced from above 17.5% to 2.1% and 1.7% for the pelvis and the head patients, respectively. As our method suppresses only low-frequency shading artifacts, patient anatomy and contrast were retained in the corrected images for both cases. Our shading correction algorithm on CBCT images offers several advantages. It has a high efficiency, since it is deterministic and directly operates on the reconstructed images. It requires no prior information or assumptions, which not only achieves the merits of CBCT-based treatment monitoring by retaining the patient anatomy, but also facilitates its clinical use as an efficient image-correction solution.
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Priorimask guided image reconstruction (p-MGIR) for ultra-low dose cone-beam computed tomography. Phys Med Biol 2015; 60:8505-24. [DOI: 10.1088/0031-9155/60/21/8505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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A method of surface marker location optimization for tumor motion estimation in lung stereotactic body radiation therapy. Med Phys 2015; 42:244-53. [PMID: 25563264 DOI: 10.1118/1.4903888] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Accurately localizing lung tumor localization is essential for high-precision radiation therapy techniques such as stereotactic body radiation therapy (SBRT). Since direct monitoring of tumor motion is not always achievable due to the limitation of imaging modalities for treatment guidance, placement of fiducial markers on the patient's body surface to act as a surrogate for tumor position prediction is a practical alternative for tracking lung tumor motion during SBRT treatments. In this work, the authors propose an innovative and robust model to solve the multimarker position optimization problem. The model is able to overcome the major drawbacks of the sparse optimization approach (SOA) model. METHODS The principle-component-analysis (PCA) method was employed as the framework to build the authors' statistical prediction model. The method can be divided into two stages. The first stage is to build the surrogate tumor matrix and calculate its eigenvalues and associated eigenvectors. The second stage is to determine the "best represented" columns of the eigenvector matrix obtained from stage one and subsequently acquire the optimal marker positions as well as numbers. Using 4-dimensional CT (4 DCT) and breath hold CT imaging data, the PCA method was compared to the SOA method with respect to calculation time, average prediction accuracy, prediction stability, noise resistance, marker position consistency, and marker distribution. RESULTS The PCA and SOA methods which were both tested were on all 11 patients for a total of 130 cases including 4 DCT and breath-hold CT scenarios. The maximum calculation time for the PCA method was less than 1 s with 64 752 surface points, whereas the average calculation time for the SOA method was over 12 min with 400 surface points. Overall, the tumor center position prediction errors were comparable between the two methods, and all were less than 1.5 mm. However, for the extreme scenarios (breath hold), the prediction errors for the PCA method were not only smaller, but were also more stable than for the SOA method. Results obtained by imposing a series of random noises to the surrogates indicated that the PCA method was much more noise resistant than the SOA method. The marker position consistency tests using various combinations of 4 DCT phases to construct the surrogates suggested that the marker position predictions of the PCA method were more consistent than those of the SOA method, in spite of surrogate construction. Marker distribution tests indicated that greater than 80% of the calculated marker positions fell into the high cross correlation and high motion magnitude regions for both of the algorithms. CONCLUSIONS The PCA model is an accurate, efficient, robust, and practical model for solving the multimarker position optimization problem to predict lung tumor motion during SBRT treatments. Due to its generality, PCA model can also be applied to other imaging guidance system whichever using surface motion as the surrogates.
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Adaptive beamlet-based finite-size pencil beam dose calculation for independent verification of IMRT and VMAT. Med Phys 2015; 42:1836-50. [PMID: 25832074 DOI: 10.1118/1.4914858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The use of sophisticated dose calculation procedure in modern radiation therapy treatment planning is inevitable in order to account for complex treatment fields created by multileaf collimators (MLCs). As a consequence, independent volumetric dose verification is time consuming, which affects the efficiency of clinical workflow. In this study, the authors present an efficient adaptive beamlet-based finite-size pencil beam (AB-FSPB) dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. METHODS The computational time of finite-size pencil beam (FSPB) algorithm is proportional to the number of infinitesimal and identical beamlets that constitute an arbitrary field shape. In AB-FSPB, dose distribution from each beamlet is mathematically modeled such that the sizes of beamlets to represent an arbitrary field shape no longer need to be infinitesimal nor identical. As a result, it is possible to represent an arbitrary field shape with combinations of different sized and minimal number of beamlets. In addition, the authors included the model parameters to consider MLC for its rounded edge and transmission. RESULTS Root mean square error (RMSE) between treatment planning system and conventional FSPB on a 10 × 10 cm(2) square field using 10 × 10, 2.5 × 2.5, and 0.5 × 0.5 cm(2) beamlet sizes were 4.90%, 3.19%, and 2.87%, respectively, compared with RMSE of 1.10%, 1.11%, and 1.14% for AB-FSPB. This finding holds true for a larger square field size of 25 × 25 cm(2), where RMSE for 25 × 25, 2.5 × 2.5, and 0.5 × 0.5 cm(2) beamlet sizes were 5.41%, 4.76%, and 3.54% in FSPB, respectively, compared with RMSE of 0.86%, 0.83%, and 0.88% for AB-FSPB. It was found that AB-FSPB could successfully account for the MLC transmissions without major discrepancy. The algorithm was also graphical processing unit (GPU) compatible to maximize its computational speed. For an intensity modulated radiation therapy (∼12 segments) and a volumetric modulated arc therapy fields (∼90 control points) with a 3D grid size of 2.0 × 2.0 × 2.0 mm(3), dose was computed within 3-5 and 10-15 s timeframe, respectively. CONCLUSIONS The authors have developed an efficient adaptive beamlet-based pencil beam dose calculation algorithm. The fast computation nature along with GPU compatibility has shown better performance than conventional FSPB. This enables the implementation of AB-FSPB in the clinical environment for independent volumetric dose verification.
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Four dimensional digital tomosynthesis using on-board imager for the verification of respiratory motion. PLoS One 2014; 9:e115795. [PMID: 25541710 PMCID: PMC4277366 DOI: 10.1371/journal.pone.0115795] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/26/2014] [Indexed: 11/26/2022] Open
Abstract
Purpose To evaluate respiratory motion of a patient by generating four-dimensional digital tomosynthesis (4D DTS), extracting respiratory signal from patients' on-board projection data, and ensuring the feasibility of 4D DTS as a localization tool for the targets which have respiratory movement. Methods and Materials Four patients with lung and liver cancer were included to verify the feasibility of 4D-DTS with an on-board imager. CBCT acquisition (650–670 projections) was used to reconstruct 4D DTS images and the breath signal of the patients was generated by extracting the motion of diaphragm during data acquisition. Based on the extracted signal, the projection data was divided into four phases: peak-exhale phase, mid-inhale phase, peak-inhale phase, and mid-exhale phase. The binned projection data was then used to generate 4D DTS, where the total scan angle was assigned as ±22.5° from rotation center, centered on 0° and 180° for coronal “half-fan” 4D DTS, and 90° and 270° for sagittal “half-fan” 4D DTS. The result was then compared with 4D CBCT which we have also generated with the same phase distribution. Results The motion of the diaphragm was evident from the 4D DTS results for peak-exhale, mid-inhale, peak-inhale and mid-exhale phase assignment which was absent in 3D DTS. Compared to the result of 4D CBCT, the view aliasing effect due to arbitrary angle reconstruction was less severe. In addition, the severity of metal artifacts, the image distortion due to presence of metal, was less than that of the 4D CBCT results. Conclusion We have implemented on-board 4D DTS on patients data to visualize the movement of anatomy due to respiratory motion. The results indicate that 4D-DTS could be a promising alternative to 4D CBCT for acquiring the respiratory motion of internal organs just prior to radiotherapy treatment.
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Panoramic measures for oral bone mass in detecting osteoporosis: a systematic review and meta-analysis. J Dent Res 2014; 94:17S-27S. [PMID: 25365969 DOI: 10.1177/0022034514554949] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Different quantitative and qualitative indices calculated on oral panoramic radiographs have been proposed as useful tools to screen for reduced skeletal bone mineral density (BMD). Our aim was to systematically review the literature on linear and qualitative panoramic measures and to assess the accuracy of these indices by performing a meta-analysis of their sensitivity and specificity. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement was followed. Fifty studies were included in the qualitative appraisal and 19 were considered for meta-analysis. The methodological quality of the retrieved studies, assessed with the QUADAS-2 tool, was on average low. Three indices were reported by most of the studies: mandibular cortical width, panoramic mandibular index, and the Klemetti index. Mandibular cortical width presented with a better accuracy in excluding osteopenia/osteoporosis (specificity), since patients with a cortical width more than 4 mm had a normal BMD in 90% of the cases. Almost all studies used a cutoff of 0.3 for the panoramic mandibular index, resulting in an estimated sensitivity and specificity in detecting reduced BMD, respectively, of 0.723 (SE 0.160; 95% confidence interval [CI], 0.352-0.926) and 0.733 (SE 0.066; 95% CI, 0.587-0.841). The presence of any kind of mandibular cortical erosion gave an estimated sensitivity and specificity in detecting reduced BMD, respectively, of 0.789 (SE 0.031; 95% CI, 0.721-0.843) and 0.562 (SE 0.047; 95% CI, 0.47-0.651) and a sensitivity and specificity in detecting osteoporosis, respectively, of 0.806 (SE 0.105; 95% CI, 0.528-0.9200) and 0.643 (SE 0.109; 95% CI, 0.417-0.820). The mandibular cortical width, panoramic mandibular index, and Klemetti index are overall useful tools that potentially could be used by dentists to screen for low BMD. Their limitations are mainly related to the experience/agreement between different operators and the different image quality and magnification of the panoramic radiographs.
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A low-complexity 2-point step size gradient projection method with selective function evaluations for smoothed total variation based CBCT reconstructions. Phys Med Biol 2014; 59:6565-82. [DOI: 10.1088/0031-9155/59/21/6565] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Effect of vitamin levels and different stocking densities on performance, nutrient digestibility, and blood characteristics of growing pigs. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 26:241-6. [PMID: 25049782 PMCID: PMC4093153 DOI: 10.5713/ajas.2012.12434] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 10/15/2012] [Accepted: 10/05/2012] [Indexed: 11/27/2022]
Abstract
This study was conducted to evaluate the effects of dietary vitamin levels and stocking densities on growth performance, nutrient digestibility, and blood characteristics in growing pigs. A 2×3 factorial (two vitamin levels, three regimens of stocking densities) arrangement was utilized with 96 pigs (23.10×0.95 kg initial body weight and 63 d of age) for 36 d. The pigs were allocated to pens with different stocking density (0.64, 0.48, and 0.38 m(2)/pig, respectively). The diets used in this study were a normal diet (based on NRC) and a high level of vitamin diet (2-fold higher than normal diet). The ADG and ADFI of pigs were decreased as the stocking density increased (p = 0.03 and p = 0.01, respectively). The G/F of pigs was 5% lower in the high vitamin treatment (p = 0.03) as compared with the control treatment. The apparent total tract digestibility (ATTD) of DM and N digestibility was negatively affected by the high level of vitamin in diets (p = 0.05 and p = 0.04, respectively). Moreover, a significant and negative effect on the ATTD of N was detected in the large groups (linear, p = 0.02). Blood cortisol concentration was increased with increasing stocking density (linear, p = 0.05), and was decreased by high level of vitamin (p = 0.04) at the end of this experiment. Stocking density also caused a linear reduction in WBC concentration (p = 0.05). Our data indicated that the principal effect of stocking density was not reliant on dietary vitamin levels. In conclusion, results indicated that doubling the vitamin supplementation did not improve the growth performance of pigs in high density. However, the blood cortisol concentration was decreased but the ATTD of N digestibility was impaired by high level of vitamin diet.
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Effect of dietary supplementation of procyanidin on growth performance and immune response in pigs. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 27:131-9. [PMID: 25049935 PMCID: PMC4093277 DOI: 10.5713/ajas.2013.13359] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 10/11/2013] [Accepted: 09/04/2013] [Indexed: 11/27/2022]
Abstract
This study was performed to determine the effect of dietary supplementation of procyanidin on growth performance, blood characteristics, and immune function in growing pigs. In experiment 1 (Exp. 1), thirty-two crossbred pigs with an initial BW of 19.2±0.3 kg were allocated into 4 treatments for an 8-wk experiment: i) CON (basal diet), ii) MOS 0.1 (basal diet+0.1% mannanoligosaccharide), iii) Pro-1 (basal diet+0.01% procyanidin), and iv) Pro-2 (basal diet+0.02% procyanidin). Pigs fed Pro-1 and Pro-2 diets had greater (p<0.05) gain:feed ratio compared with those fed CON or MOS 0.1 diets. Serum creatinine concentration was less (p<0.05) in Pro-2 treatment than those in CON, MOS 0.1 and Pro-1 treatments. In Exp. 2, twelve pigs (BW 13.4±1.3 kg) received basal diet with i) 0 (CON), ii) 0.02% (Pro-0.02%), and iii) 0.04% procyanidin (Pro-0.04%) for 4 wk. Concentration of platelets was lower (p<0.05) in the Pro-0.04% group compared to CON at 24 h after lipopolysaccharide (LPS) challenge. In addition, secretion of cytokines from cultured peripheral blood mononuclear cells (PBMC) in the presence or absence of procyanidin was examined. The levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were lower (p<0.05) in Pro (LPS-stimulated PBMCs+procyanidin) than those in CON (LPS-stimulated PBMCs+PBS) at 4 h after LPS challenge. These data suggest that dietary addition of procyanidin improves feed efficiency and anti-inflammatory cytokines of pigs.
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Effects of Dietary Fat Types on Growth Performance, Pork Quality, and Gene Expression in Growing-finishing Pigs. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 25:1759-67. [PMID: 25049542 PMCID: PMC4094162 DOI: 10.5713/ajas.2012.12416] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 09/16/2012] [Accepted: 09/04/2012] [Indexed: 11/27/2022]
Abstract
This study was performed to determine the effects of dietary fat sources, i.e., beef tallow, soybean oil, olive oil and coconut oil (each 3% in feed), on the growth performance, meat quality and gene expression in growing-finishing pigs. A total of 72 crossbred pigs (Landrace×Large White×Duroc) were used at 71±1 kg body weight (about 130 d of age) in 24 pens (320×150 cm) in a confined pig house (three pigs per pen) with six replicate pens per treatment. The growing diet was given for periods of 14±3 d and the finishing diet was given for periods of 28±3 d. The fat type had no significant effect either on growth performance or on chemical composition or on meat quality in growing-finishing pigs. Dietary fat type affected fatty acid composition, with higher levels of unsaturated fatty acids (UFAs) and monounsaturated fatty acids (MUFAs) in the olive oil group. Microarray analysis in the Longissimus dorsi identified 6 genes, related to insulin signaling pathway, that were differentially expressed among the different feed groups. Real time-PCR was conducted on the six genes in the longissimus dorsi muscle (LM). In particular, the genes encoding the protein kinase, cAMP-dependent, regulatory, type II, alpha (PRKAR2A) and the catalytic subunit of protein phosphatase 1, beta isoform (PPP1CB) showed the highest expression level in the olive oil group (respectively, p<0.05, p<0.001). The results of this study indicate that the type of dietary fat affects fatty acid composition and insulin signaling-related gene expression in the LM of pigs.
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Evaluation of Houttuynia cordata and Taraxacum officinale on Growth Performance, Nutrient Digestibility, Blood Characteristics, and Fecal Microbial Shedding in Diet for Weaning Pigs. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 25:1439-44. [PMID: 25049500 PMCID: PMC4093006 DOI: 10.5713/ajas.2012.12215] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 07/11/2012] [Accepted: 07/03/2012] [Indexed: 11/27/2022]
Abstract
A total of 144 pigs ((Landrace×Yorkshire)×Duroc] with an average initial BW of 8.45±0.57 kg were used in a 5-wk growth trial. Pigs were randomly allocated to 4 treatments with 9 replications per pen in a randomized complex block design. Dietary treatments included: i) CON (basal diet), ii) ANT (CON+tylosin 1 g/kg), iii) H1 (CON+H. cordata 1 g/kg) and iv) T1 (CON+T. officinale 1 g/kg). In this study, pigs fed the ANT and T1 treatment had a higher (p<0.05) average daily gain (ADG) and gain:feed (G:F) ratio than those fed CON and H1 treatment. Dietary ANT and T1 treatment led to a higher energy digestibility than the CON group. No difference (p>0.05) was observed on the growth performance and apparent total tract digestibility with H1 supplementation compared with the CON treatment. The inclusion of ANT treatment led to a higher (p<0.05) lymphocyte concentration compared with the CON treatment. Dietary supplementation of herbs did not affect (p>0.05) the blood characteristics (white blood cell (WBC), red blood cell (RBC), IgG, lymphocyte). No difference was observed on (p<0.05) fecal microbial shedding (E. coli and lactobacillus) between ANT and CON groups. Treatments H1 and T1 reduced the fecal E. coli concentration compared with the CON treatment, whereas the fecal lactobacillus concentration was not affected by the herb supplementation (p>0.05). In conclusion, the inclusion of T. officinale (1 g/kg) increased growth performance, feed efficiency, energy digestibility similarly to the antibiotic treatment. Dietary supplementation of T. officinale and H. cordata (1 g/kg) reduced the fecal E. coli concentration in weaning pigs.
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Heterogeneity of mucosal mast cell infiltration in subgroups of patients with esophageal chest pain. Neurogastroenterol Motil 2014; 26:786-93. [PMID: 24602134 DOI: 10.1111/nmo.12325] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 01/30/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND Although there is growing evidence that an increase in mucosal mast cells (MMCs) in the small and large intestine is associated with visceral hypersensitivity, few studies have evaluated MMCs in humans with esophageal symptoms. The aim of this study was to investigate esophageal MMC distribution in patients with non-cardiac chest pain (NCCP) and to examine the association between the number of gut MMCs and other functional gastrointestinal disorders. METHODS Forty-two consecutive NCCP patients and 10 healthy controls completed a questionnaire for bowel symptoms, chest pain intensity score, and psychologic depression. Esophageal, duodenal, and rectal MMCs were identified immunohistochemically and quantified by image analysis. KEY RESULTS Numbers of MMCs were significantly higher in NCCP patients vs healthy controls (11.8 ± 5.6 vs 7.6 ± 3.7 MMCs/high-power field, p = 0.026). In comparison of subgroups classified by 24-h impedance-pH monitoring, esophageal MMC counts were highest in the hypersensitive esophagus group (p < 0.01) and were also significantly increased in the functional chest pain group (p < 0.05). A positive correlation between esophageal and duodenal MMC counts was observed in patients with functional dyspepsia (FD; Spearman ρ = 0.604, p = 0.037). In particular, patients with clinical overlap with irritable bowel syndrome showed a strong positive correlation between esophageal and rectal MMC numbers (Spearman ρ = 0.857, p = 0.010). CONCLUSIONS & INFERENCES Among NCCP patients, increased MMC infiltration occurs in subgroups with hypersensitive esophagus and functional chest pain. In subpopulations with overlap with FD or irritable bowel syndrome, esophageal MMC counts demonstrated significant positive correlations with duodenal or rectal MMC counts.
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Esophageal mucosal mast cell infiltration and changes in segmental smooth muscle contraction in noncardiac chest pain. Dis Esophagus 2014; 28:512-9. [PMID: 24766344 DOI: 10.1111/dote.12231] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mast cells release potent mediators that alter enteric nerve and smooth muscle functions and may contribute to the pathogenesis of functional gastrointestinal disorders. The goal of this study was to determine if mucosal mast cell infiltration was associated with smooth muscle segmental changes in esophageal contraction. All patients with noncardiac chest pain (NCCP) were divided into two groups consisting of patients with non-erosive reflux disease or functional chest pain (FCP) according to the results of ambulatory 24 hours esophageal pH monitoring and high-resolution manometry. Pressure-volume (PV) was calculated by multiplying the length of the esophageal segment, duration of the contraction, and mean pressure over the entire space-time box (P mean). Quantification of mast cells was performed in five consecutive nonoverlapping immunostained sections. Spearman correlation analysis showed that the distal segment PV correlated with the mast cell count in all of the patients combined and in patients with FCP with correlation coefficients of 0.509 and 0.436, respectively (P = 0.004 and P = 0.042). Similar findings were observed for the segmental ratio of distal to proximal smooth muscle PV in all patients and in patients with FCP (correlation coefficients 0.566; P = 0.001 and correlation coefficients 0.525; P = 0.012, respectively). Mucosal mast cell infiltration was associated with distal esophageal contraction as a key pathophysiologic factor of NCCP.
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