Abstract:
:Adaptive histogram equalization techniques are known to be effective for the enhancement of contrast in portal images acquired during radiotherapy treatments. A significant drawback is the loss of definition on the edges of the treatment field. Analysis of this problem shows that it can be remedied by separating the treatment field from the background prior to the enhancement, and using only the pixels within the field boundary in the enhancement procedure. An edge extraction algorithm has been developed for delineating the treatment field in portal images, and consists of four modules that are applied to the original portal image in sequence. In the first step, edges are enhanced with a derivative of Gaussian operator that assures high response to the field edges relative to anatomical or other edges in the image. Pixels for which the response of the edge operator was the strongest are subsequently connected by an edge following algorithm to produce a raw contour of the field. In the last two steps the contour is refined by converting it into straight line segments and appending to the contour any parts of the field edge that might have been missed out during the initial edge following. The final contour encloses exclusively those pixels that belong to the treatment field, and the adaptive histogram equalization is applied selectively to this region. The combination of edge detection and selective enhancement was shown to produce images of superior contrast on the patient's anatomical features as well as accurate definition of treatment field edges.
journal_name
Med Physjournal_title
Medical physicsauthors
Leszczynski KW,Shalev S,Cosby NSdoi
10.1118/1.596807subject
Has Abstractpub_date
1992-05-01 00:00:00pages
611-21issue
3eissn
0094-2405issn
2473-4209journal_volume
19pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:Sterile radiation reduction gloves have been widely used in the past decade to provide modest decreases in operator hand dose when the hands are placed in the field of view (FOV). While multiple publications have quantified the potential dose reduction from the use of such gloves, possible effects on the patien...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734747
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:This article presents a computer-aided diagnosis technique for improving the accuracy of the early diagnosis of Alzheimer's disease (AD). Two hundred and ten 18F-FDG PET images from the ADNI initiative [52 normal controls (NC), 114 mild cognitive impairment (MCI), and 53 AD subjects] are studied. METHODS:The p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3488894
更新日期:2010-11-01 00:00:00
abstract:PURPOSE:Pulmonary magnetic-resonance-imaging (MRI) and x-ray computed-tomography have provided strong evidence of spatially and temporally persistent lung structure-function abnormalities in asthmatics. This has generated a shift in their understanding of lung disease and supports the use of imaging biomarkers as inter...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4948999
更新日期:2016-06-01 00:00:00
abstract:PURPOSE:In previous work, the authors developed and demonstrated the concept of an image reconstruction procedure aimed to unify gated and dynamic nuclear cardiac imaging, which the authors have termed five-dimensional (5D) SPECT. Gated imaging permits the clinician to evaluate wall motion and, through the use of stres...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3481507
更新日期:2010-09-01 00:00:00
abstract::Current methods for imaging joint motion are limited to either two-dimensional (2D) video fluoroscopy, or to animated motions from a series of static three-dimensional (3D) images. 3D movement patterns can be detected from biplane fluoroscopy images matched with computed tomography images. This involves several x-ray ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2000647
更新日期:2005-09-01 00:00:00
abstract:PURPOSE:The automated segmentation of each lung and trachea in CT scans is commonly taken as a solved problem. Indeed, existing approaches may easily fail in the presence of some abnormalities caused by a disease, trauma, or previous surgery. For robustness, we present ALTIS (implementation is available at http://lids....
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13773
更新日期:2019-11-01 00:00:00
abstract:PURPOSE:When an intensity-modulated radiation beam is delivered to a moving target, the interplay effect between dynamic beam delivery and the target motion due to miss-synchronization can cause unpredictable dose delivery. The portal dose image in electronic portal imaging device (EPID) represents radiation attenuated...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4799941
更新日期:2013-05-01 00:00:00
abstract:PURPOSE:To develop and test the feasibility of a two-pass iterative reconstruction algorithm with material decomposition designed to obtain quantitative iodine measurements in digital breast tomosynthesis. METHODS:Contrast-enhanced mammography has shown promise as a cost-effective alternative to magnetic resonance ima...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14400
更新日期:2020-10-01 00:00:00
abstract::While simple, intravascular brachytherapy (IVB) presents a considerable potential for harm to the patient. The medical physicist maintains the responsibility to minimize the likelihood of operational problems or dosimetric errors. The principals for safe operation remain the same as with any radiotherapy treatment: to...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1524167
更新日期:2002-12-01 00:00:00
abstract:PURPOSE:The primary feasibility steps of demonstrating the ability of microwave-induced thermoacoustic (TA) in phantoms have been previously reported. However, none were shown to target a diseased site in living subjects in thermoacoustic tomography (TAT) field so far. To determine the expressions of oncogenic surface ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3466696
更新日期:2010-08-01 00:00:00
abstract::A computer dose model for a low energy gamma-emitting stent in a heterogeneous medium is described. The method is based on the Sievert model which is adapted to the dose-point-kernel (DPK) model to compute the dose distribution about filtered gamma sources (Sievert-DPK model). The new gamma stent model can take into a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1380214
更新日期:2001-07-01 00:00:00
abstract:PURPOSE:Metal artifact reduction (MAR) is a major problem and a challenging issue in x-ray computed tomography (CT) examinations. Iterative reconstruction from sinograms unaffected by metals shows promising potential in detail recovery. This reconstruction has been the subject of much research in recent years. However,...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4950722
更新日期:2016-06-01 00:00:00
abstract:PURPOSE:Computational models are widely used during the design and characterization of microwave ablation (MWA) devices, and have been proposed for pretreatment planning. Our objective was to assess three-dimensional (3D) transient temperature and ablation profiles predicted by MWA computational models with temperature...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14318
更新日期:2020-09-01 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::Direct comparisons of the National Institute of Standards and Technology's (NIST) Ritz 20 kV to 100 kV standard free-air ionization chamber and a portable variable-length free-air ionization chamber designed by the University of Wisconsin-Madison Accredited Dosimetry Calibration Laboratory (UW-ADCL) were made on NISTs...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598148
更新日期:1997-08-01 00:00:00
abstract::Surgical guidance with fluorescence has been demonstrated in individual clinical trials for decades, but the scientific and commercial conditions exist today for a dramatic increase in clinical value. In the past decade, increased use of indocyanine green based visualization of vascular flow, biliary function, and tis...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4951732
更新日期:2016-06-01 00:00:00
abstract:PURPOSE:Though failure mode and effects analysis (FMEA) is becoming more widely adopted for risk assessment in radiation therapy, to our knowledge, its output has never been validated against data on errors that actually occur. The objective of this study was to perform FMEA of a stereotactic body radiation therapy (SB...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4919440
更新日期:2015-06-01 00:00:00
abstract:PURPOSE:The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914398
更新日期:2015-04-01 00:00:00
abstract:PURPOSE:The objective of this study is to evaluate requirements for radionuclide-based solid tumor therapy by assessing the radial dose distribution of beta-particle-emitting and alpha-particle-emitting molecules localized either solely within endothelial cells of tumor vasculature or diffusing from the vasculature thr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3431999
更新日期:2010-06-01 00:00:00
abstract::We have made a comparative investigation of the estimated spectra obtained by the Laplace transform analysis of the transmitted exposure data measured in an absorption study of a 4-MV x-ray beam. Four transform pair models currently used with this method have been evaluated. It has been determined that the Archer-Wagn...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595878
更新日期:1986-05-01 00:00:00
abstract:PURPOSE:The authors investigate the extent to which Response Evaluation Criteria in Solid Tumors (RECIST) can predict tumor volumes in ideal geometric settings and using clinical data. METHODS:The authors consider a hierarchy of models including uniaxial ellipsoids, general ellipsoids, and composites of ellipsoids, us...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3577602
更新日期:2011-05-01 00:00:00
abstract:PURPOSE:Dual source CT (DSCT) systems utilize two measurement systems (A) and (B) offset by about 90 degrees. A special challenge in DSCT is cross-scattered radiation, i.e., scattered radiation from x-ray tube (B) detected in detector (A) and vice versa. Cross-scattered radiation can produce artifacts and degrade the c...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3504606
更新日期:2010-11-01 00:00:00
abstract::Receiver operating characteristic (ROC) methodology is widely used in evaluating medical imaging modalities. While appropriate in some cases, it has several drawbacks when the detection task, e.g., nodule detection, involves localizing the abnormality. Free-response receiver operating characteristic (FROC) methodology...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596358
更新日期:1989-07-01 00:00:00
abstract::Three-dimensional water phantoms are routinely used when acquiring the data necessary to commission medical linear accelerators. A new water phantom controller has been developed at our institution that is unique in several aspects. The water phantom controller is based on an IBM XT compatible computer. This has been ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596414
更新日期:1989-01-01 00:00:00
abstract:PURPOSE:To improve the performance of a computer-aided detection (CAD) system for mass detection by using four-view information in screening mammography. METHODS:The authors developed a four-view CAD system that emulates radiologists' reading by using the craniocaudal and mediolateral oblique views of the ipsilateral ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3560462
更新日期:2011-04-01 00:00:00
abstract:PURPOSE:In this report, the authors introduce the general concept of the completeness map, as a means to evaluate the completeness of data acquired by a given CT system design (architecture and scan mode). They illustrate the utility of completeness map by applying the completeness map concept to a number of candidate ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3700172
更新日期:2012-05-01 00:00:00
abstract::An addendum to the AAPM's TG-51 protocol for the determination of absorbed dose to water in megavoltage photon beams is presented. This addendum continues the procedure laid out in TG-51 but new kQ data for photon beams, based on Monte Carlo simulations, are presented and recommendations are given to improve the accur...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4866223
更新日期:2014-04-01 00:00:00
abstract:PURPOSE:The Synchrony respiratory motion tracking of the CyberKnife system purports to provide real-time tumor motion compensation during robotic radiosurgery. Such a complex delivery system requires thorough quality assurance. In this work, RADPOS applicability as a dose and position quality assurance tool for CyberKn...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13102
更新日期:2018-07-25 00:00:00
abstract::The dosimetry protocols DIN 6800-2 and AAPM TG-51, both based on the absorbed dose to water concept, are compared in their theoretical background and in their application to electron dosimetry. The agreement and disagreement in correction factors and energy parameters used in both protocols will be shown and discussed...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1414008
更新日期:2001-11-01 00:00:00
abstract::The fast imaging method named skipped phase encoding and edge deghosting (SPEED) has been demonstrated to reduce scan time considerably with typical magnetic resonance imaging data. In this work, SPEED is simplified with improved efficiency to accelerate the scan of sparse objects; we refer to this method as S-SPEED. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2750966
更新日期:2007-08-01 00:00:00