Abstract:
PURPOSE:Automated segmentation could improve the efficiency of modeling-based pelvic organ prolapse (POP) evaluations. However, segmentation performance is limited by the blurry soft tissue boundaries. In this study, we aimed to present a hybrid solution for uterus, rectum, bladder, and levator ani muscle segmentation by combining a convolutional neural network (CNN) and a level set method. METHODS:We used 24 sagittal pelvic floor magnetic resonance (MR) series from six anterior vaginal prolapse and six posterior vaginal prolapse subjects (a total 528 MR images). The stress MR images were performed both at rest and at maximal Valsalva. We assigned 264 images for training, 132 images for validation, and 132 images for testing. A CNN was designed by introducing a multi-resolution features pyramid module (MRFP) into an encoder-decoder model. Depth separable convolution and pretraining were used to improve model convergence. Multiclass cross entropy loss and multiclass Dice loss were used for model training. The dice similarity coefficient (DSC) and average surface distance (ASD) were used for evaluating the segmentation results. To prove the effectiveness of our model, we compared it with advanced segmentation methods including Deeplabv3+, U-Net, and FCN-8s. The ablation study was designed to quantify the contributions of MRFP, the encoder network, and pretraining. Besides, we investigated the working mechanism of MRFP in the segmentation network by comparing our model with three of its variants. Finally, the level set method was used to improve the CNN model further. RESULTS:Dice loss showed better segmentation performance than multiclass cross entropy loss. MRFP was efficacious for different encoder networks. With MRFP, U-Net and U-Net-X (X represents Xception encoder network) have improved the DSC, on average by 6.8 and 5.3 points. Compared with different CNN models, our model achieved the highest average DSC of 65.6 points and the lowest average ASD of 2.9 mm. With the level set method, the DSC of our model improved to 69.4 points. CONCLUSIONS:MRFP proved to be effective in addressing the blurry soft tissue boundary problem on pelvic floor MR images. A hybrid solution based on CNN and level set method was presented for pelvic organ segmentation both at rest and at maximal Valsalva; with this method, we achieved state-of-the-art results.
journal_name
Med Physjournal_title
Medical physicsauthors
Feng F,Ashton-Miller JA,DeLancey JOL,Luo Jdoi
10.1002/mp.14377subject
Has Abstractpub_date
2020-09-01 00:00:00pages
4281-4293issue
9eissn
0094-2405issn
2473-4209journal_volume
47pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:To design an efficient method for utilizing phase-space source models in the GPU-based Monte Carlo (MC) dose calculation engine gDPM. METHODS:In GPU-based MC algorithms, particles are transported in parallel on different threads. Particles of different types and energies can require significantly different exe...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735565
更新日期:2012-06-01 00:00:00
abstract::A method is developed to smooth intensity-modulated beam delivery while considering hardware constraints. The method uses matrix algebra to model MLC leaf motion and hardware constraints such as interleaf digitization, synchronization requirements, and intersegment field abutment to deliver intensity modulated beam se...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1521121
更新日期:2002-12-01 00:00:00
abstract::In this study we address the problem of predicting the position of a moving lung tumor during respiration on the basis of external breathing signals--a technique used for beam gating, tracking, and other dynamic motion management techniques in radiation therapy. We demonstrate the use of neural network filters to corr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2134958
更新日期:2005-12-01 00:00:00
abstract::System modeling is used to investigate the effect of various system parameters on the image quality in CCD-based x-ray imaging systems. The systems considered consist of a typical phosphor-based scintillating screen coupled to a CCD through lens or fiberoptic taper. Two applications, chest radiography and mammography,...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598072
更新日期:1997-02-01 00:00:00
abstract::Model-based deformable organ registration techniques using the finite element method (FEM) have recently been investigated intensively and applied to image-guided adaptive radiotherapy (IGART). These techniques assume that human organs are linearly elastic material, and their mechanical properties are predetermined. U...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2163838
更新日期:2006-02-01 00:00:00
abstract::Optical-resolution photoacoustic microscopy (OR-PAM) has been validated as a valuable tool for label-free volumetric microvascular imaging. More importantly, the advantages of noninvasiveness and measurement consistency suggest the use of OR-PAM for chronic imaging of intact microcirculation. Here, such chronic imagin...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.3137572
更新日期:2009-06-01 00:00:00
abstract::Recent working groups of the AAPM [Almond et al., Med. Phys. 26, 1847 (1999)] and the IAEA (Andreo et al., Draft V.7 of "An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water," IAEA, 2000) have described guidelines to base reference dosimetry of high energy photon beams on absorb...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1328081
更新日期:2000-12-01 00:00:00
abstract:PURPOSE:Stereotactic ablative body radiotherapy (SABR) for lung patients can be performed with volumetric-modulated arc therapy (VMAT) plans using off-axis target geometry to allow treatment in their CBCT verified position. For patient-specific quality assurance measurements using the PTW Octavius 4D phantom (PTW, Frei...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12805
更新日期:2018-04-01 00:00:00
abstract::Myocardial beta adrenergic receptor (beta-AR) concentration can substantially decrease in congestive heart failure and significantly increase in chronic volume overload, such as in severe aortic valve regurgitation. Positron emission tomography (PET) with an appropriate ligand-receptor model can be used for noninvasiv...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2402585
更新日期:2007-01-01 00:00:00
abstract:PURPOSE:Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. METHODS:In the variational image segmen...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4945046
更新日期:2016-05-01 00:00:00
abstract::Tumor cells can be killed by heating to 42.5 degrees C. It is convenient to localize heating by passing electric current at 500 kHz through tissue between a pair of electrodes. It is desirable to determine, for a given electrode-tissue configuration, what the resulting field and, therefore, current distribution will b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594235
更新日期:1976-07-01 00:00:00
abstract::In this paper, two new boundary tracing algorithms for segmentation of breast masses are presented. These new algorithms are based on the dynamic programming-based boundary tracing (DPBT) algorithm proposed in Timp and Karssemeijer, [S. Timp and N. Karssemeijer, Med. Phys. 31, 958-971 (2004)] The DPBT algorithm contai...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2791034
更新日期:2007-11-01 00:00:00
abstract:PURPOSE:The authors introduce a novel method for defining standardized uptake values (SUVs) in PET∕CT based on routinely collected CT data. The goal of the study is to reduce, if possible, the variability of SUV in a heterogeneous population. Two well established methods for defining SUV are based on body weight (BW) a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4816656
更新日期:2013-09-01 00:00:00
abstract:PURPOSE:To provide results of water calorimetry and ion chamber measurements in high-energy electron beams carried out at the National Research Council Canada (NRC). There are three main aspects to this work: (a) investigation of the behavior of ionization chambers in electron beams of different energies with focus on ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12463
更新日期:2017-10-01 00:00:00
abstract::Intensity Modulated Arc Therapy (IMAT) is a rotational variant of Intensity Modulated Radiation Therapy (IMRT) that can be implemented with or without angular dose rate optimization. The purpose of this study is to determine the inter-relationship among arc range, Multi-Leaf Collimator (MLC) leaf positions and angular...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2965975
更新日期:2008-07-01 00:00:00
abstract::Fluoroscopy is a low dose imaging technique. As such, a very sensitive detector is required to create images of good quality. Present day flat panel active matrix read out systems introduce an amount of noise that inhibits present direct and indirect methods from producing optimal quality images at fluoroscopic exposu...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1513157
更新日期:2002-11-01 00:00:00
abstract:PURPOSE:To examine schemes to grade the severity of metal susceptibility artifacts on image quality using cardiac MRI pulse sequences. METHODS:A post-thoracotomy patient was simulated with a stainless steel sternal wire (Syneture,MA; size=6, diameter=48mm), placed securely on an ACR MRI phantom. Phantom was scanned on...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734785
更新日期:2012-06-01 00:00:00
abstract::The hybrid algorithms developed recently for the reconstruction of fan-beam images possess computational and noise properties superior to those of the fan-beam filtered backprojection (FFBP) algorithm. However, the hybrid algorithms cannot be applied directly to a halfscan fan-beam sinogram because they require knowle...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1288239
更新日期:2000-09-01 00:00:00
abstract:PURPOSE:To develop a deformable mapping technique to match corresponding lesions between digital breast tomosynthesis (DBT) and automated breast ultrasound (ABUS) images. METHODS:External fiducial markers were attached to the surface of two CIRS multi-modality compressible breast phantoms (A and B) containing multiple...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13113
更新日期:2018-10-01 00:00:00
abstract::An important aspect of the intensity modulated radiotherapy (IMRT) process is that of optimizing the beam intensity profiles. Most such methods use a comparison between the defined dose distribution (including prescription dose and dose limits for critical structures) and the current distribution. The comparison may i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1428756
更新日期:2002-01-01 00:00:00
abstract::The dosimetric characteristics of a new dedicated radiosurgical treatment unit are systematically measured in terms of its percent depth dose, beam profile, and relative scatter factor. High-resolution diode detector, mini-ion-chamber detector, and conventional Kodak XV films are used to measure dosimetric data for a ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1494830
更新日期:2002-08-01 00:00:00
abstract:PURPOSE:To quantify the inter fraction variation of spatial location of high dose regions of OARs in MR-image based cervix brachytherapy using rigid registration algorithm. METHODS:Retrospective analysis of 27 previously treated patients under EMBRACE multi-centric trial was evaluated. Each patient had two application...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735513
更新日期:2012-06-01 00:00:00
abstract::We have previously investigated a method of high-energy x-ray spectral reconstruction from transmission data by direct resolution of a matrix system. This technique uses the spectral vectorial algebra formalism. The resolution has previously been tested on a 12 MV photon beam. To extend and to test the validity of the...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597998
更新日期:1997-05-01 00:00:00
abstract:PURPOSE:To evaluate the replacement of Cerrobend by copper for electron beam cutouts. METHODS:The dosimetric comparisons for circular copper-and Cerrobend-cutouts with diameters (1.0, 2.0, 3.0, 5.0, 7.5, 10.0, and 12.5 cm) were made using electron beams with energies (6, 9, 12, 16, and 20 MeV) from 3 Varian accelerato...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735336
更新日期:2012-06-01 00:00:00
abstract::Many papers discussed the I value for water given by the ICRU, concluding that a value of about 80 +/- 2 eV instead of 67.2 eV would reproduce measured ion depth-dose curves. A change in the I value for water would have an effect on the stopping power and, hence, on the water-to-air stopping power ratio, which is impo...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3085877
更新日期:2009-04-01 00:00:00
abstract::Measurements of a 670-MeV/amu 20Ne beam at the Lawrence Berkeley Laboratory Bevalac heavy-ion accelerator with various thicknesses of water absorber were obtained with the BERKLET. The BERKLET, a simple three-stage solid-state telescope detector, has been described previously. This instrument measures the linear energ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596536
更新日期:1990-03-01 00:00:00
abstract:PURPOSE:In breast radiotherapy with intensity modulation, it is a well established practice to extend the dose fluence outside the limit of the body contour to account for small changes in size and position of the target and the rest of the tissues due to respiration or to possible oedema. A simple approach is not appl...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3598442
更新日期:2011-07-01 00:00:00
abstract:PURPOSE:The outcome of radiotherapy can be further improved by combining irradiation with dose enhancers such as high-Z nanoparticles. Since 2004, spectacular results have been obtained when low-energy x-ray irradiations have been combined with nanoparticles. Recently, the same combination has been explored in hadron t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4934370
更新日期:2015-11-01 00:00:00
abstract::One limitation to the widespread implementation of Monte Carlo (MC) patient dose-calculation algorithms for radiotherapy is the lack of a general and accurate source model of the accelerator radiation source. Our aim in this work is to investigate the sensitivity of the photon-beam subsource distributions in a MC sour...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1884385
更新日期:2005-04-01 00:00:00
abstract:PURPOSE:Modern clinical accelerators are capable of producing ion beams from protons up to neon. This work compares the depth dose distribution and corresponding dose averaged linear energy transfer (LET) distribution, which is related to the biological effectiveness, for different ion beams (¹H, ⁴He, ⁶Li, ⁸Be, ¹⁰B, ¹²...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3662911
更新日期:2011-12-01 00:00:00