Abstract:
:This paper proposes a new respiratory gated radiation treatment system that allows real-time tumor localization while avoiding invasive operation to a patient. The proposed system employs a three-dimensional (3D) ultrasound device, a 3D digital localizer, and a real-time image processing system. At the planning time, CT and 3D ultrasound reference data are simultaneously acquired under a breath-hold condition. At the treatment time, ultrasound data on three orthogonal planes are acquired and transferred to the image processing system on a real-time basis. Subsequently, normalized image correlation indices using the reference and the real-time ultrasound data are calculated for the three orthogonal planes after performing real-time coordinate transform using the 3D digital localizer attached to an ultrasound probe. Prior to the system execution, the coordinate transform matrices are partially calculated using an ultrasound calibration phantom and the 3D digital localizer. A trigger pulse to a linac can be generated when the normalized image correlation index exceeds a predetermined threshold level. Experiments have been carried out using a moving-target phantom that simulates a patient respiratory motion. We have observed that the variation of the calculated real-time correlation index synchronizes with the periodical motion of the moving-target, suggesting that real-time localization for a moving tumor is feasible with the proposed system.
journal_name
Med Physjournal_title
Medical physicsauthors
Sawada A,Yoda K,Kokubo M,Kunieda T,Nagata Y,Hiraoka Mdoi
10.1118/1.1634482subject
Has Abstractpub_date
2004-02-01 00:00:00pages
245-50issue
2eissn
0094-2405issn
2473-4209journal_volume
31pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:In Stereotactic body radiation therapy (SBRT) higher dose per fraction is delivered to patients and thus the need for an accurate dose computation is further elevated. However under such conditions of small field geometries, the electronic equilibrium can be lost, making it challenging for the dose-calculation ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735539
更新日期:2012-06-01 00:00:00
abstract::Quantitative analysis of dynamic gadolinium-DTPA (diethylenetriamine pentaacetic acid) enhanced magnetic resonance imaging (MRI) is emerging as a highly sensitive tool for detecting malignant breast tissue. Three-dimensional rapid imaging techniques, such as keyhole MRI, yield high temporal sampling rates to accuratel...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598576
更新日期:1999-05-01 00:00:00
abstract::For radiation dosimetry calculations of radiolabeled monoclonal antibodies, (MAB), pharmacokinetics are critical. Specifically, pharmacokinetic modeling is a useful component of estimation of cumulated activity in various source organs in the body. It is thus important to formulate general methods of pharmacokinetic m...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.597047
更新日期:1993-03-01 00:00:00
abstract:PURPOSE:To investigate using 3D γ analysis for IMRT and VMAT QA. METHODS:We explored and studied 3D γ-analysis by comparing TPS computed and EPID back-projection reconstructed doses in patient's CT images. Two 3D γ quantities, γ(PTV) and γ(10), were proposed and studied for evaluating the QA results, and compared to 2...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4711755
更新日期:2012-06-01 00:00:00
abstract::The half-life of two I-125 encapsulated clinical seeds was measured with a Si(Li) semiconductor detector. Two measurements of each seed yielded an average half-life of 59.56 +/- 0.17 days. The results are discussed in terms of the influence of possible I-126 contamination and leakage of I-125 activity through encapsul...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595423
更新日期:1983-11-01 00:00:00
abstract::Quantification of transit time of a remote after-loading high dose rate (HDR) brachytherapy source is important both for accurate treatment planning and for quality assurance checks. In this investigation, an HDR-1000 well ionization chamber and a precision electrometer are used to measure the transit time of the Ir-1...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1386779
更新日期:2001-08-01 00:00:00
abstract:PURPOSE:Talbot-Lau x-ray interferometry provides information about the scattering and refractive properties of an object - in addition to the object's attenuation features. Until recently, this method was ineligible for imaging human-sized objects as it is challenging to adapt Talbot-Lau interferometers (TLIs) to the r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12889
更新日期:2018-06-01 00:00:00
abstract:PURPOSE:To review the issues a physicist may encounter in a community hospital during the transition from film/paper charts to a paperless environment with ARIA and a TrueBeam LINAC. With a lean budget, it was necessary for the physics group to take on the project management responsibilities in order save costs. This w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735291
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To accurately and efficiently implement charged particle transport in a magnetic field in EGSnrc and validate the code for the use in phantom and ion chamber simulations. METHODS:The effect of the magnetic field on the particle motion and position is determined using one- and three-point numerical integrations...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4954318
更新日期:2016-07-01 00:00:00
abstract:PURPOSE:To automatically and efficiently segment the lesion area of the colonoscopy polyp image, a polyp segmentation method has been presented. METHODS:An ensemble model of pretrained convolutional neural networks was proposed, using Unet-VGG, SegNet-VGG, and PSPNet. Firstly, the Unet-VGG is obtained by the first 10 ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13865
更新日期:2019-12-01 00:00:00
abstract::When a catheter is inserted through an artery, the wall shear stress increases and the secondary flow exhibits an increased number of instantaneous vortices. These effects become more evident when the annular gap between the catheter and the artery becomes more narrow. Accordingly it is suggested that these factors ma...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596448
更新日期:1990-09-01 00:00:00
abstract:PURPOSE:To develop and investigate a continuous path optimization methodology to traverse prescribed non-coplanar IMRT beams with variant SADs, by orchestrating the couch and gantry movement with zero-collision, minimal patient motion consequence and machine travel time. METHODS:We convert the given collision zone def...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735996
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To assess and compare the dosimetric impact of dynamic multileaf collimator (DMLC) tracking and gating as motion correction strategies to account for intrafraction motion during conventionally fractionated prostate radiotherapy. METHODS:A dose reconstruction method was used to retrospectively assess the dose d...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4892605
更新日期:2014-09-01 00:00:00
abstract::The purpose of this paper is to determine the correlation between dose-volume histogram (DVH) and dose wall-histogram (DWH) in the evaluation of rectal complications for prostate cancer patients treated with three-dimensional conformal radiotherapy (3D-CRT). A retrospective analysis of DVHs and DWHs of a subset of 25 ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1951427
更新日期:2005-08-01 00:00:00
abstract:PURPOSE:On-board MRI can provide superb soft tissue contrast for improving liver SBRT localization. However, the availability of on-board MRI in clinics is extremely limited. On the contrary, on-board kV imaging systems are widely available on radiotherapy machines, but its capability to localize tumors in soft tissue ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12998
更新日期:2018-07-01 00:00:00
abstract::This paper outlines a method for determining proper removal-diffusion parameters to be used in removal-diffusion theory calculations for the purpose of BNCT treatment planning. Additionally, this paper demonstrates that, given the proper choice of removal-diffusion parameters, removal-diffusion theory may provide an a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1386424
更新日期:2001-09-01 00:00:00
abstract::We designed a novel force/torque moment transducer with six degrees of freedom. This new sensor is used for measuring the forces and torque moments exerted by static magnetic resonance imaging (MRI) fields on various medical implants, instruments, and ballistic shell fragments. To determine the location of strongest e...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597853
更新日期:1996-06-01 00:00:00
abstract::We are developing computerized feature extraction and classification methods to analyze malignant and benign microcalcifications on digitized mammograms. Morphological features that described the size, contrast, and shape of microcalcifications and their variations within a cluster were designed to characterize microc...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598389
更新日期:1998-10-01 00:00:00
abstract:PURPOSE:To construct a Monte Carlo (MC)-based simulation model for analyzing the dependence of tumor oxygen distribution on different variables related to tumor vasculature [blood velocity, vessel-to-vessel proximity (vessel proximity), and inflowing oxygen partial pressure (pO2)]. METHODS:A voxel-based tissue model c...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4892386
更新日期:2014-09-01 00:00:00
abstract:PURPOSE:The response of human cells to applied electrical signals depends on the cellular health status, because it is influenced by the composition and structure of the main cellular components. Therefore, electrical impedance-based techniques can be considered as sensitive tools to investigate healthy or disease stat...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14425
更新日期:2020-10-01 00:00:00
abstract:PURPOSE:Mammographic density of glandular breast tissue has a masking effect that can reduce lesion detection accuracy and is also a strong risk factor for breast cancer. Therefore, accurate quantitative estimation of breast density is clinically important. In this study, we investigate experimentally the feasibility o...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13031
更新日期:2018-06-03 00:00:00
abstract:PURPOSE:High dose rate (HDR) brachytherapy is a radiation treatment technique capable of delivering large dose rates to the tumor. Radiation is delivered using remote afterloaders to drive highly active sources (commonly (192)Ir with an air KERMA strength range between 20,000 and 40,000 U, where 1 U = 1 μGy m(2)/h in a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4822736
更新日期:2013-11-01 00:00:00
abstract::An instrument for daily beam checks of medical accelerators is described. Using three silicon diodes, the instrument provides information about calibration, beam symmetry, flatness, and energy variation for both photon and electron beams. Operating characteristics of the instrument and the electronic circuit design pe...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595756
更新日期:1985-07-01 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::Angioplasty balloons inflated with a solution of the beta-emitter Re-188 have been used for intravascular brachytherapy to prevent restenosis. Coronary stents are in extensive clinical use for the treatment of de novo atherosclerotic stenoses. In this study, the effect of an interposed stent on the dose distribution h...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1533749
更新日期:2003-02-01 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:PURPOSE:To establish accurate experimental dosimetry techniques for reference dose measurements in nonstandard composite fields. METHODS:A cylindrical PMMA phantom filled with water was constructed, at the center of which reference absorbed dose to water for a head and neck IMRT delivery was measured. Based on the pro...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3392247
更新日期:2010-06-01 00:00:00
abstract:PURPOSE:To obtain on-treatment volumetric patient anatomy during respiratory gated volumetric modulated arc therapy (VMAT). METHODS:On-board imaging device integrated with Linacs offers a viable tool for obtaining patient anatomy during radiation treatment delivery. In this study, the authors acquired beam-level kV im...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.4794925
更新日期:2013-04-01 00:00:00
abstract::Current dosimetry protocols for clinical protons do not take into account any secondary electron fluence perturbation in ion chambers. In this work, we performed a systematic study of secondary electron fluence perturbation factors for spherical and cylindrical ion chambers in proton beams (70-250 MeV). The electron f...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1406519
更新日期:2001-10-01 00:00:00
abstract:PURPOSE:The aim of this paper is to investigate the accuracy of a laser∕camera surface imaging system (Sentinel) when used on patients treated in the thorax or pelvic regions and to evaluate system employment conditions and patient setup procedures that provide more accurate results. METHODS:The system was tested on t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4769428
更新日期:2013-01-01 00:00:00