Abstract：
PURPOSE:To evaluate the performance and efficacy for intensity inhomogeneity correction of various sequences of the human brain in 7T MRI using the extended version of the unified segmentation algorithm. MATERIALS:Ten healthy volunteers were scanned with four different sequences (2D spin echo [SE], 3D fast SE, 2D fast spoiled gradient echo, and 3D time-of-flight) by using a 7T MRI system. Intensity inhomogeneity correction was performed using the "New Segment" module in SPM8 with four different values (120, 90, 60, and 30 mm) of full width at half maximum (FWHM) in Gaussian smoothness. The uniformity in signals in the entire white matter was evaluated using the coefficient of variation (CV); mean signal intensities between the subcortical and deep white matter were compared, and contrast between subcortical white matter and gray matter was measured. The length of the lenticulostriate (LSA) was measured on maximum intensity projection (MIP) images in the original and corrected images. RESULTS:In all sequences, the CV decreased as the FWHM value decreased. The differences of mean signal intensities between subcortical and deep white matter also decreased with smaller FWHM values. The contrast between white and gray matter was maintained at all FWHM values. LSA length was significantly greater in corrected MIP than in the original MIP images. CONCLUSIONS:Intensity inhomogeneity in 7T MRI can be successfully corrected using SPM8 for various scan sequences.
journal_name
Med Physjournal_title
Medical physicsauthors
Uwano I,Kudo K,Yamashita F,Goodwin J,Higuchi S,Ito K,Harada T,Ogawa A,Sasaki Mdoi
10.1118/1.4860954subject
Has Abstractpub_date
2014-02-01 00:00:00pages
022302issue
2eissn
0094-2405issn
2473-4209journal_volume
41pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:Like Medical Physics, Imaging Informatics encompasses concepts touching every aspect of the imaging chain from image creation, acquisition, management and archival, to image processing, analysis, display and interpretation. The two disciplines are in fact quite complementary, with similar goals to improve the quality ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735777
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurem...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4754797
更新日期：2012-10-01 00:00:00
abstract：:Current edge detection methods used to determine coronary artery dimensions from digital (DSA) images suffer a strong dependence on the system's modulation transfer function (MTF). The videodensitometric algorithms are less sensitive to MTF blurring, yet still result in an overestimation of the vessel size of 10% to 2...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596370
更新日期：1989-03-01 00:00:00
abstract：PURPOSE:Colitis refers to inflammation of the inner lining of the colon that is frequently associated with infection and allergic reactions. In this paper, we propose deep convolutional neural networks methods for lesion-level colitis detection and a support vector machine (SVM) classifier for patient-level colitis dia...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12399
更新日期：2017-09-01 00:00:00
abstract：:Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597412
更新日期：1994-10-01 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：PURPOSE:Low-dose CT has attracted increasing attention due to growing concerns about radiation exposure in medical scans. However, the frugal use of x-ray radiation inevitably reduces the quality of the CT images, introducing artifacts such as noise and streaks which make the reconstructed images difficult to read in c...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4736528
更新日期：2012-08-01 00:00:00
abstract：:We investigated the utility of three manual planimetric methods to quantify carotid plaque volume. A single observer measured 15 individual plaques from 15 three-dimensional (3D) ultrasound (3D US) images of patients ten times each using three different planimetric approaches. Individual plaque volumes were measured (...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2715487
更新日期：2007-04-01 00:00:00
abstract：:This paper investigates the effect of the waterproofing sleeve on the calibration of kilovoltage photon beams (50-300 kV). The sleeve effect correction factor, ps has been calculated using the Monte Carlo method as the ratios of the air kerma in an air cavity of a cylindrical chamber without the waterproofing sleeve t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598039
更新日期：1997-09-01 00:00:00
abstract：PURPOSE:The purpose of this study was to characterize the Hounsfield unit (HU) distributions of mesothelioma and other tissues present in contrast-enhanced thoracic CT scans, to compare the HU distributions of mesothelioma, muscle, and liver by scanner and reconstruction filter/kernel combination, and to assess interpa...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3537610
更新日期：2011-02-01 00:00:00
abstract：:Accurate and reliable thermometry is essential in the development of microwave-induced hyperthermal cancer therapy. While temperature measurements in strong electromagnetic fields usually require special sensors, this does not hold true for interstitial radiator/sensor systems. Miniature thermistors (with metallic lea...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595261
更新日期：1983-05-01 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：PURPOSE:It is estimated that 7% of women in the western world will develop palpable breast cysts in their lifetime. Even though cysts have been correlated with risk of developing breast cancer, many of them are benign and do not require follow-up. We develop a method to discriminate benign solitary cysts from malignant...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12110
更新日期：2017-03-01 00:00:00
abstract：:Modern computed tomography (CT) scanners use cone-beam configurations for increasing volume coverage, improving x-ray-tube utilization, and yielding isotropic spatial resolution. Recently, there have been significant developments in theory and algorithms for exact image reconstruction from cone-beam projections. In pa...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2337270
更新日期：2006-10-01 00:00:00
abstract：PURPOSE:The recent development of multifocal stereotactic radiosurgery (SRS) using a single isocenter volumetric modulated arc theory (VMAT) technique warrants a re-examination of the quality assurance (QA) tolerances for routine mechanical QA recommended by the American Association of Physicists in Medicine Task Group...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4962471
更新日期：2016-10-01 00:00:00
abstract：:A high sensitivity (HS) model of radiochromic film is receiving increasing use. The film's linear sensitometric response in the range of 0.5-40 Gy would make this film an ideal candidate for complex dosimetry applications that require tissue equivalence. This study investigates the potential use for clinical dosimetry...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1883565
更新日期：2005-04-01 00:00:00
abstract：PURPOSE:The aim of this work is to investigate the predictive power of a common conventional intensity modulated radiation therapy (IMRT) quality assurance (QA) performance metric, the gamma passing rate (%GP), through the analysis of the sensitivity and of the correlation between %GP and different dose discrepancies b...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4767763
更新日期：2012-12-01 00:00:00
abstract：:This article provides a quantitative evaluation of Varian Medical Systems' beam matching procedure. A one-dimensional y analysis is employed to investigate the level of agreement of matched beams. A customized concept of one-dimensional gamma evaluation was designed. Our algorithm first performs a "local" fit of the r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2745239
更新日期：2007-07-01 00:00:00
abstract：PURPOSE:One technical barrier to patient-specific computed tomography (CT) dosimetry has been the lack of computational tools for the automatic patient-specific multi-organ segmentation of CT images and rapid organ dose quantification. When previous CT images are available for the same body region of the patient, the a...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14131
更新日期：2020-06-01 00:00:00
abstract：PURPOSE:The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides exce...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4914860
更新日期：2015-04-01 00:00:00
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 t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596807
更新日期：1992-05-01 00:00:00
abstract：:The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the de...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598804
更新日期：1999-12-01 00:00:00
abstract：:When a beam-modifying filter such as a wedge or a compensator is placed in an x-ray beam, scattered photons are generated in the filter material. The magnitude of the dose contribution from these photons for a 4-MV x-ray beam was measured. At a distance of 30 cm from the filter, a copper sheet of 1-cm thickness produc...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595923
更新日期：1986-01-01 00:00:00
abstract：PURPOSE:To investigate the sensitivity of the plan-class specific correction factor to dose distributions in composite nonstandard field dosimetry. METHODS:A cylindrical water-filled PMMA phantom was constructed at the center of which reference absorbed dose could be measured. Ten different TomoTherapy(®)-based IMRT f...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3669487
更新日期：2012-01-01 00:00:00
abstract：PURPOSE:To implement the DMAIC (Define-Measure-Analyze-Improve-Control) can be used for customizing the patient-specific QA by designing site-specific range tolerances. METHODS:The DMAIC framework (process flow diagram, cause and effect, Pareto chart, control chart, and capability analysis) were utilized to determine ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12721
更新日期：2018-02-01 00:00:00
abstract：:For Monte Carlo linac simulations and patient dose calculations, it is important to accurately determine the phase space parameters of the initial electron beam incident on the target. These parameters, such as mean energy and radial intensity distribution, have traditionally been determined by matching the calculated...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2168433
更新日期：2006-04-01 00:00:00
abstract：PURPOSE:In this study, a dedicated device for ion chamber measurements of absorbed dose-to-water for a Nucletron microSelectron-v2 HDR (192)Ir brachytherapy source is presented. The device uses two ionization chambers in a so-called sandwich assembly. Using this setup and by taking the average reading of the two chambe...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4816673
更新日期：2013-09-01 00:00:00
abstract：:Modulation of the activity of the subthalamic nucleus (STN) using deep brain stimulation (DBS) in patients with advanced Parkinson's disease is the most common procedure performed today by functional neurosurgeons. The STN contours cannot be entirely identified on common 1.5 T images; in particular, the ventromedial b...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2936229
更新日期：2008-07-01 00:00:00
abstract：:Two side-by-side energy windows, one at the photopeak and one at lower energy, are sometimes employed in quantitative SPECT studies. We measured the count-rate losses at moderately high activities of 131I for two multihead Anger cameras in such a dual-window-acquisition mode by imaging a decaying source composed of tw...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598162
更新日期：1998-01-01 00:00:00
abstract：:This study presents experimental results about the effective depth of penetration and about the radiofrequency (rf) power absorption in humans as a function of frequency. The frequency range investigated covers 10 up to 220 MHz. For the main part, the results were derived from bench measurements of the quality factor ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595995
更新日期：1987-11-01 00:00:00
