Abstract：
:Deformable image registration is an important tool for image-guided radiotherapy. Physics-model-based deformable image registration using finite element analysis is one of the methods currently being investigated. The calculation accuracy of finite element analysis is dependent on given boundary conditions, which are usually based on the surface matching of the organ in two images. Such a surface matching, however, is hard to obtain from medical images. In this study, we developed a new boundary condition to circumvent the traditional difficulties. Finite element contact-impact analysis was employed to simulate the interaction between the organ of interest and the surrounding body. The displacement loading is not necessarily specified. The algorithm automatically deforms the organ model into the minimum internal energy state. The analysis was performed on CT images of the lung at two different breathing phases (exhalation and full inhalation). The result gave the displacement vector map inside the lung. Validation of the result showed satisfactory agreement in most parts of the lung. This approach is simple, operator independent and may provide improved accuracy of the prediction of organ deformation.
journal_name
Med Physjournal_title
Medical physicsauthors
Zhang T,Orton NP,Mackie TR,Paliwal BRdoi
10.1118/1.1774131subject
Has Abstractpub_date
2004-09-01 00:00:00pages
2412-5issue
9eissn
0094-2405issn
2473-4209journal_volume
31pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：PURPOSE:Scatter is a major factor degrading the image quality of cone beam computed tomography (CBCT). Conventional scatter correction strategies require handcrafted analytical models with ad hoc assumptions, which often leads to less accurate scatter removal. This study aims to develop an effective scatter correction ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13583
更新日期：2019-07-01 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：:Monte Carlo calculations have been performed for the purpose of characterizing the dosimetric properties of three brachytherapy sources. The three sources are manufactured by Syncor Pharmaceuticals Inc. and consist of two 125I seeds (BT-125-1 and BT-125-2) and one 103Pd seed (BT-103-3). The BT-125-1 and BT-125-2 seed ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1469627
更新日期：2002-05-01 00:00:00
abstract：:The relative sensitivity of the half-value layer (HVL) method as a quality index for megavoltage x-ray beams is examined by theoretical calculation and experimental measurements for 4-, 6-, 10-, and 25-MV x-ray beams. It is shown that lower atomic number materials are more sensitive to beam quality changes than higher...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595794
更新日期：1985-01-01 00:00:00
abstract：:Quantitative evaluation of cardiac image data obtained using multidetector row computed tomography (CT) is compromised by partial scan reconstructions, which improve the temporal resolution but significantly increase image-to-image CT number variations for a fixed region of interest compared to full reconstruction ima...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2805476
更新日期：2007-12-01 00:00:00
abstract：PURPOSE:Carpal tunnel syndrome (CTS) is the common entrapment neuropathy that occurs due to compression of the median nerve at the wrist. Ultrasound images have been used to highlight anatomical variants of the median nerve, and CTS is thought to be associated to enlargement of the cross-sectional area (CSA) of the med...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4767754
更新日期：2012-12-01 00:00:00
abstract：PURPOSE:The impact and the development of aneurysms depend to a significant degree on the exchange of liquid between the regular vessel and the pathological extension. A better understanding of this process will lead to improved prediction capabilities. The aim of the current study was to investigate fluid-exchange in ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4929758
更新日期：2015-10-01 00:00:00
abstract：PURPOSE:To increase diagnostic accuracy of breast MRI by increasing temporal resolution and more accurately sampling the early kinetics of contrast media uptake. We tested the feasibility of accelerating bilateral breast DCE-MRI by reducing the FOV, allowing aliasing, and unfolding the resulting images. METHODS:Previo...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12747
更新日期：2018-03-01 00:00:00
abstract：PURPOSE:Recently, brain tumor segmentation has made important progress. However, the quality of manual labels plays an important role in the performance, while in practice, it could vary greatly and in turn could substantially mislead the learning process and decrease the accuracy. We need to design a mechanism to comb...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14480
更新日期：2020-09-24 00:00:00
abstract：PURPOSE:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4772075
更新日期：2013-01-01 00:00:00
abstract：PURPOSE:IAEA TRS-398 notes that cylindrical ionization chambers are preferred for reference proton dosimetry. If a cylindrical ionization chamber is used in a phantom to measure the dose as a function of depth, the effective point of measurement (EPOM) must be taken into account. IAEA TRS-398 recommends a displacement ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4921617
更新日期：2015-07-01 00:00:00
abstract：:A beam intensity monitor was tested in a 230-MeV proton beam at the Loma Linda Proton Therapy Accelerator during its commissioning at Fermi National Accelerator Laboratory. The intensity monitor was designed to regulate the beam intensity extracted from the proton synchrotron. The proton beam is tunable between 70 and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596636
更新日期：1991-07-01 00:00:00
abstract：PURPOSE:Timely identification of systematic changes in radiation delivery of an imaging system can lead to a reduction in risk for the patients involved. However, existing quality assurance programs involving the routine testing of equipment performance using phantoms are limited in their ability to effectively carry o...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3524224
更新日期：2011-01-01 00:00:00
abstract：PURPOSE:The aim of this study was to use MRI gel dosimetry to determine the dose profile of 50kV MAGNUM® X-ray tube, MOXTEK Inc., in order to calibrate small solid dosimeters of alanine, tooth enamel and LiF-TLDs, commonly used in clinical quality assurance and datation dosimetry. METHODS:MAGIC-f polymer gel was kept ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735203
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:The repair rate conventionally assumed to be constant during the entire radiation course. However, increasing evidences from animal studies show that the repair process may slow down with time and the experimental data does not fit an exponential pattern. To address this enigma, we presented a generalized linea...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735058
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:X-ray fluorescence computer tomography (XFCT) is a new molecular imaging modality which uses x-ray excitation to stimulate the emission of fluorescent photons in high atomic number contrast agents. Scatter contamination is one of the main challenges in XFCT imaging which limits the molecular sensitivity. When p...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12997
更新日期：2018-05-25 00:00:00
abstract：:An overall practical dosimetric study of a 10-MV photon beam produced by a Varian Clinac-18 linear accelerator is presented. In particular measurements were made to provide data which could be utilized in computerized dosage calculations using the concept of dividing the radiation beam into primary and scatter compone...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594311
更新日期：1977-03-01 00:00:00
abstract：:The dosimetry of 192Ir linear sources with a commercial treatment planning computer system has been evaluated. Reference dose rate data were selected from the literature and normalized in a manner consistent with our clinical and dosimetric terminology. The results of the computer calculations are compared to the refe...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595685
更新日期：1985-09-01 00:00:00
abstract：:In this paper, a unified framework of iterative algebraic reconstruction for emission computed tomography (ECT) and its application to positron emission tomography (PET) is presented. The unified framework is based on an algebraic image restoration model and contains conventional iterative algebraic reconstruction alg...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596954
更新日期：1993-11-01 00:00:00
abstract：PURPOSE:Researchers write many computer programs with unique implementations, usually requiring a great amount of effort for other researchers to learn how to install, configure, and use. Some programs require specialized hardware platforms such as GPU workstation or CPU cluster, which may not readily available for man...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735274
更新日期：2012-06-01 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:To correlate the Cole relaxation frequencies obtained from measurements of the electrical properties of breast tissue to the presence or absence of cancer. METHODS:Four-lead impedance measurements were obtained on ex vivo specimens extracted during surgery from 187 volunteer patients. Data were acquired with a...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4725172
更新日期：2012-07-01 00:00:00
abstract：:Our purpose in this work was to assess the reliability of the calibration coefficient for magnetic resonance water proton chemical shift temperature mapping. Over a six month period, the calibration coefficient was measured 15 times in several different phantoms. A highly linear relationship between water proton chemi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598864
更新日期：2000-01-01 00:00:00
abstract：:A method to determine the bone mineral density of the calcaneum has been reported earlier by our laboratory. In this method, the calcaneum is irradiated by a 60-keV photon beam from 241Am source and both the coherent and Compton scattered photons are detected by a high-purity Ge detector. The bone mineral density is d...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595669
更新日期：1985-07-01 00:00:00
abstract：:Optimal visualization of moving structures such as the heart and coronary arteries using digital radiographic imaging systems is a difficult problem that can involve tradeoffs between temporal, spatial, and density resolution. The motion dependence of four angiographic measures of vessel dimensions is given and demons...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595651
更新日期：1985-11-01 00:00:00
abstract：PURPOSE:To present a noninvasive technique for directly measuring the CT bow-tie filter attenuation with a linear array x-ray detector. METHODS:A scintillator based x-ray detector of 384 pixels, 307 mm active length, and fast data acquisition (model X-Scan 0.8c4-307, Detection Technology, FI-91100 Ii, Finland) was use...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4932364
更新日期：2015-11-01 00:00:00
abstract：:Determination of the relaxation times T1 and T2 which are important for tissue characterization generally requires the use of different pulse sequences in magnetic resonance imaging. In this study, a new pulse sequence which facilitates simultaneous determination of the T1 and T2 times is presented. Determination take...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595867
更新日期：1986-09-01 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:To assess current education, practices, attitudes, and perceptions pertaining to ethics and professionalism in medical physics. METHODS:A link to a web-based survey was distributed to the American Association of Physicists in Medicine (AAPM) e-mail membership list, with a follow-up e-mail sent two weeks later....
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4797463
更新日期：2013-04-01 00:00:00
abstract：:Intravascular brachytherapy requires that the dose be specified within millimeters of the source. High dose gradients near brachytherapy sources require that the source-detector distance be accurately known for dosimetry purposes. Solid phantoms can be designed to accommodate these stringent requirements. This study r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1376176
更新日期：2001-06-01 00:00:00
