Abstract:
PURPOSE:Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckle contrast diffuse correlation tomography (scDCT), enables incorporation of complex optical property heterogeneities and sample boundaries. When combined with a reflectance-based design, this system facilitates a rapid segue into flow contrast imaging of larger, in vivo applications such as humans. METHODS:A highly sensitive CCD camera was integrated into a reflectance-based optical system. Four long-coherence laser source positions were coupled to an optical switch for sequencing of tomographic data acquisition providing multiple projections through the sample. This system was investigated through incorporation of liquid and solid tissue-like phantoms exhibiting optical properties and flow characteristics typical of human tissues. Computer simulations were also performed for comparisons. A uniquely encountered smear correction algorithm was employed to correct point-source illumination contributions during image capture with the frame-transfer CCD and reflectance setup. RESULTS:Measurements with scDCT on a homogeneous liquid phantom showed that speckle contrast-based deep flow indices were within 12% of those from standard DCT. Inclusion of a solid phantom submerged below the liquid phantom surface allowed for heterogeneity detection and validation. The heterogeneity was identified successfully by reconstructed 3D flow contrast tomography with scDCT. The heterogeneity center and dimensions and averaged relative flow (within 3%) and localization were in agreement with actuality and computer simulations, respectively. CONCLUSIONS:A custom cost-effective CCD-based reflectance 3D flow imaging system demonstrated rapid acquisition of dense boundary data and, with further studies, a high potential for translatability to real tissues with arbitrary boundaries. A requisite correction was also found for measurements in the fashion of scDCT to recover accurate speckle contrast of deep tissues.
journal_name
Med Physjournal_title
Medical physicsauthors
Huang C,Irwin D,Lin Y,Shang Y,He L,Kong W,Luo J,Yu Gdoi
10.1118/1.4922206subject
Has Abstractpub_date
2015-07-01 00:00:00pages
4000-6issue
7eissn
0094-2405issn
2473-4209journal_volume
42pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:Wide bore CT scanners use extended field-of-view (eFOV) reconstruction algorithms to attempt to recreate tissue truncated due to large patient habitus. Radiation therapy planning systems rely on accurate CT numbers in order to correctly plan and calculate radiation dose. This study looks at the impact of eFOV r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13299
更新日期:2019-02-01 00:00:00
abstract:PURPOSE:The recent introduction of digital tomosynthesis imaging into routine clinical use has enabled the acquisition of volumetric patient data within a standard radiographic examination. Tomosynthesis requires the acquisition of multiple projection views, requiring additional dose compared to a standard projection e...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3250907
更新日期:2009-12-01 00:00:00
abstract::The synchronization of dynamic multileaf collimator (DMLC) response with respiratory motion is critical to ensure the accuracy of DMLC-based four dimensional (4D) radiation delivery. In practice, however, a finite time delay (response time) between the acquisition of tumor position and multileaf collimator response ne...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1915017
更新日期:2005-06-01 00:00:00
abstract:PURPOSE:Respiratory motion compensation in PET/CT and PET/MRI is essential as motion is a source of image degradation (motion blur, attenuation artifacts). In previous work, we developed a direct method for joint image reconstruction/motion estimation (JRM) for attenuation-corrected (AC) respiratory-gated PET, which us...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12253
更新日期:2017-06-01 00:00:00
abstract::A formulation of the single energy photon transport problem is cast in the form of a series of convolutions over the primary fluence distribution with invariant kernels. A method is developed for compensating for the variant intervoxel attenuation in the scattered dose distribution by means of an invariant correction ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595964
更新日期:1986-07-01 00:00:00
abstract::Empirical functions that describe primary beam profiles for radiotherapy treatment planning systems generally account for finite source size only on beams unmodified by blocks, wedges, or compensating filters. To incorporate the effects of extended sources on such modified beams and to treat the effect of an extended ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596222
更新日期:1988-09-01 00:00:00
abstract:PURPOSE:It is important for many quantitative brain studies to label meaningful anatomical regions in MR brain images. However, due to high complexity of brain structures and ambiguous boundaries between different anatomical regions, the anatomical labeling of MR brain images is still quite a challenging task. In many ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4940399
更新日期:2016-02-01 00:00:00
abstract::The purpose of this study was to investigate if interfraction and intrafraction motion in free-breathing and gated lung IMRT can lead to systematic dose differences between 3DCT and 4DCT. Dosimetric effects were studied considering the breathing pattern of three patients monitored during the course of their treatment ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2821704
更新日期:2008-01-01 00:00:00
abstract::Depth dose characteristics of 24-MV beams from a medical linear accelerator at various SSDs have been measured. The dose buildup, percent depth dose (PDD), and output were measured using ionization chambers and a diode detector under full scatter. Surface dose ranged from 8% to 51% depending upon the collimator settin...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596673
更新日期:1991-03-01 00:00:00
abstract:PURPOSE:The purpose of the work is to describe a new algorithm for the automatic detection of implanted radioactive seeds within the prostate. The algorithm is based on the traditional Hough transform. A method of quality assurance is described as well as a quantitative phantom study to determine the accuracy of the al...
journal_title:Medical physics
pub_type: 临床试验,杂志文章
doi:10.1118/1.1778837
更新日期:2004-09-01 00:00:00
abstract:PURPOSE:The accuracy and precision of computed tomography (CT) pulmonary ventilation imaging with conventional CT scanners are limited by breathing variations. We propose a method to correct for the effect of breathing variations in CT ventilation imaging based on external respiratory signals acquired throughout a scan...
journal_title:Medical physics
pub_type: 临床试验,杂志文章
doi:10.1002/mp.12634
更新日期:2018-01-01 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::Positron emission mammography (PEM) is a new, specialized imaging modality utilizing PET radiopharmaceuticals to detect breast cancer. The capabilities and limitations of PEM in detecting breast tumors were investigated with a series of phantom experiments. The PEM imager was mounted on a standard Lorad biopsy table (...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1287439
更新日期:2000-08-01 00:00:00
abstract:PURPOSE:For almost four decades bead and wire ramps have been used in the evaluation of slice width as part of QA testing for CT scanners. While each of these approaches have been recognized and accepted as reliable, in this paper we investigate the differences, advantages and limitations of these tools. Moreover, we s...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734753
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:Most modern radiotherapy machines are built with a 2D kV imaging system. Combining this imaging system with a 2D-3D inference method would allow for a ready-made option for real-time 3D tumor tracking. This work investigates and compares the accuracy of four existing 2D-3D inference methods using both motion tr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12765
更新日期:2018-03-01 00:00:00
abstract::The head-scatter factors H were examined for four different linear accelerators and were found to be similar at field sizes larger than 3 x 3 cm2. Sharply reduced values for small collimator openings were observed for all the accelerators. It is concluded that the head-scatter (or collimator-scatter) factor has two ma...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597256
更新日期:1994-01-01 00:00:00
abstract::The purposes of this research are to investigate the effectiveness of our novel image features for segmentation of anatomic regions such as the lungs and the mediastinum in chest radiographs and to develop an automatic computerized method for image processing. A total of 85 screening chest radiographs from Johns Hopki...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598277
更新日期:1998-06-01 00:00:00
abstract:PURPOSE:High-dose-rate brachytherapy (HDR-BT) is a treatment option for malignant skin diseases compared to external beam radiation therapy, HDR-BT provides improved target coverage, better organ sparing, and has comparable treatment times. This is especially true for large clinical targets with complex topologies. To ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13975
更新日期:2020-03-01 00:00:00
abstract::The Los Alamos code MCNP4A (Monte Carlo N-Particle version 4A) is currently used to simulate a variety of problems ranging from nuclear reactor analysis to boron neutron capture therapy. A graphical user interface has been developed that automatically sets up the MCNP4A geometry and radiation source requirements for a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598167
更新日期:1998-01-01 00:00:00
abstract::The American Association of Physicists in Medicine recommends that the reference dose-rate distribution, used for treatment planning for low-energy photon brachytherapy sources in routine clinical use, must be based on at least two independent determinations: one using experimentally measured dose rates and one using ...
journal_title:Medical physics
pub_type: 指南,杂志文章
doi:10.1118/1.1690712
更新日期:2004-05-01 00:00:00
abstract:PURPOSE:To evaluate dosimetric variations of planning target volume (PTV) on critical organs such as rectal wall, bladder and femoral head, when the patient size changes due to weight loss in prostate volumetric modulated arc therapy (VMAT). METHODS:Three patients with small (32.0 cm3 ), medium (48.4 cm3 ) and large (...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735610
更新日期:2012-06-01 00:00:00
abstract::We are investigating computerized methods to ultimately characterize bone trabecular pattern from clinical skeletal radiographs. In this paper, we present a "phantom" for potential use in the development and evaluation of computerized methods for characterizing radiographic trabecular patterns and ultimately bone stre...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598743
更新日期:1999-11-01 00:00:00
abstract::Motion and deformation of the cardiac wall may be measured by following the positions of implanted radiopaque markers in three dimensions, using two x-ray cameras simultaneously. Regularly, calibration of the position measurement system is obtained by registration of the images of a calibration object, containing 10-2...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598518
更新日期:1999-02-01 00:00:00
abstract:PURPOSE:The appearance of parenchymal∕stromal patterns in mammography have been characterized as having a Wiener power spectrum with an inverse power-law shape described by the exponential parameter, β. The amount of fibroglandular tissue, which can be quantified in terms of volumetric breast density (VBD), influences ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736422
更新日期:2012-08-01 00:00:00
abstract:PURPOSE:To reduce the potential of late toxicity (tissue necrosis and cognitive function loss) from brain radiotherapy, we studied a novel planning technique for MLC-equipped linear accelerators (LINACS) that reduces the high doses delivered outside the PTV, enhancing radiation dose conformity. METHODS:The feasibility...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735656
更新日期:2012-06-01 00:00:00
abstract::The assessment of the radiation dose to internal organs or to an embryo or fetus is required on occasion for risk assessment or for comparing imaging studies. Limited resources hinder the ability to accurately assess the radiation dose received to locations outside the tissue volume actually scanned during computed to...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1312809
更新日期:2000-10-01 00:00:00
abstract:PURPOSE:The objectives of this study were (a) to devise a technique for measuring quantum noise in clinical body computed tomography (CT) images and (b) to develop a model for predicting that noise with high accuracy. METHODS:The study included 83 clinical image sets at two dose levels (clinical and 50% reduced dose l...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4938588
更新日期:2016-01-01 00:00:00
abstract:PURPOSE:TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12672
更新日期:2018-01-01 00:00:00
abstract:PURPOSE:The lateral edge of a proton therapy beam is commonly used to achieve conformality to the treatment volume where critical structures reside close to the target. However, when treating shallow depths, the lateral edge of a pencil beam scanning (PBS) system may be broader than that of a double scattered (DS) syst...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4941957
更新日期:2016-03-01 00:00:00
abstract::Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3125137
更新日期:2009-06-01 00:00:00