Abstract：
:A comparison of two methods of scatter compensation in single photon emission computed tomography (SPECT) imaging is made on the basis of improvements in quantification. The methods, scatter-window subtraction and constrained deconvolution of an average point source response function (PSRF), are described; the theoretical basis of each method is also briefly assessed. Improvements in relative quantification offered by each method are measured by examining ratios of counts in hot cylinders to counts in a slightly radioactive background. The cylinder/background concentration ratio was varied by a factor of five; the sizes of the cylinders remained constant. Keeping the diameter of the cylinders constant allowed for an assessment of the effect of concentration differences, without the conflicting effect of variation in the size of the hot source. Results showed that while both scatter-window subtraction and constrained deconvolution offer quantification improvements in the final image, the method of prereconstruction deconvolution of a planar PSRF from each planar projection is substantially more successful than either scatter-window subtraction or other methods of implementing the deconvolution procedure.
journal_name
Med Physjournal_title
Medical physicsauthors
Yanch JC,Flower MA,Webb Sdoi
10.1118/1.596453subject
Has Abstractpub_date
1990-11-01 00:00:00pages
1011-22issue
6eissn
0094-2405issn
2473-4209journal_volume
17pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：PURPOSE:The image quality of dedicated cone beam breast CT (CBBCT) is limited by substantial scatter contamination, resulting in cupping artifacts and contrast-loss in reconstructed images. Such effects obscure the visibility of soft-tissue lesions and calcifications, which hinders breast cancer detection and diagnosis...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4955121
更新日期：2016-08-01 00:00:00
abstract：PURPOSE:The purpose of this study is to evaluate the performance of a recently developed benchtop dual cone-beam computed tomography (CBCT) system with two orthogonally placed tube∕detector sets. METHODS:The benchtop dual CBCT system consists of two orthogonally placed 40 × 30 cm flat-panel detectors and two conventio...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4788654
更新日期：2013-02-01 00:00:00
abstract：:A method is described for calibration of 192Ir high-dose-rate (HDR) brachytherapy afterloading systems. Since NIST does not offer calibration of ionization chambers with the gamma-ray spectrum of iridium-192, an interpolation procedure is employed, using calibrations above (137Cs, 662 keV) and below (250 kVcp, 146-keV...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596649
更新日期：1991-05-01 00:00:00
abstract：:The noise power spectrum (NPS) is a useful metric for understanding the noise content in images. To examine some unique properties of the NPS of fan beam CT, the authors derived an analytical expression for the NPS of fan beam CT and validated it with computer simulations. The nonstationary noise behavior of fan beam ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3378673
更新日期：2010-05-01 00:00:00
abstract：:We present a technique for semiautomated segmentation of human prostates using suprapubic ultrasound (US) images. In this approach, a speckle reducing anisotropic diffusion (SRAD) is applied to enhance the images and the instantaneous coefficient of variation (ICOV) is utilized for edge detection. Segmentation is acco...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1809791
更新日期：2004-12-01 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:Radioembolization with yttrium-90 microspheres may be optimized with patient-specific pretherapy treatment planning. Dose verification and validation of treatment planning methods require quantitative imaging of the post-therapy distribution of yttrium-90 (Y-90). Methods for quantitative imaging of Y-90 using b...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4962472
更新日期：2016-10-01 00:00:00
abstract：:Computer-aided diagnostic (CAD) schemes have been developed to assist radiologists in the early detection of lung cancer in radiographs and computed tomography (CT) images. In order to improve sensitivity for nodule detection, many researchers have employed a filter as a preprocessing step for enhancement of nodules. ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1581411
更新日期：2003-08-01 00:00:00
abstract：PURPOSE:Bilateral filters have been substantially exploited in numerous magnetic resonance (MR) image restoration applications for decades. Due to the deficiency of theoretical basis on the filter parameter setting, empirical manipulation with fixed values and noise variance-related adjustments has generally been emplo...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12157
更新日期：2017-04-01 00:00:00
abstract：PURPOSE:To quantify detector perturbation effects in megavoltage small photon fields and support the theoretical explanation on the nature of quality correction factors in these conditions. METHODS:In this second paper, a modern approach to radiation dosimetry is defined for any detector and applied to small photon fi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4930798
更新日期：2015-10-01 00:00:00
abstract：:We propose a new method based on statistical analysis technique to determine the minimum setup distance of a well chamber used in the calibration of 192Ir high dose rate (HDR). The chamber should be placed at least this distance away from any wall or from the floor in order to mitigate the effect of scatter. Three dif...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2911156
更新日期：2008-06-01 00:00:00
abstract：:An important point to consider in a brachytherapy dosimetry study is the phantom size involved in calculations or experimental measurements. As pointed out by Williamson [Med. Phys. 18, 776-786 (1991)] this topic has a relevant influence on final dosimetric results. Presently, one-dimensional (1-D) algorithms and newl...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1759826
更新日期：2004-07-01 00:00:00
abstract：:Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This library of pencil beams is designed to serve as a tool for both education and investigation in the field of radiotherapy optimization. The elegance of this pencil beam model stems from its cylindrical symmet...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598615
更新日期：1999-07-01 00:00:00
abstract：PURPOSE:Signal encoding in magnetic particle imaging (MPI) is achieved by moving a field-free point (FFP) through the region of interest. One way to increase the sensitivity of the method is to scan the region of interest with a field-free line (FFL) instead of the FFP. Recently, the first feasible FFL coil setup was i...
journal_title：Medical physics
pub_type： 信件
doi：10.1118/1.3447726
更新日期：2010-07-01 00:00:00
abstract：:A direct data link between a CT scanner and a radiation treatment planning system has been developed. The link transmits the data serially over a coaxial cable using the pseudo-paper-tape punch and reader (serial PIO) interfaces. The data transmission rate with error-check is approximately 25,000 8-bit bytes/s. This t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594536
更新日期：1979-09-01 00:00:00
abstract：PURPOSE:Radiosurgery uses small fields and high-radiation doses to treat intra- and extracranial lesions in a single session. The lack of a lateral electronic equilibrium and the presence of high-dose gradients in these fields are challenges for adequate measurements. The availability of radiation detectors with the hi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4752211
更新日期：2012-10-01 00:00:00
abstract：:We investigated protection strategies of organs at risk (OARs) in intensity modulated radiation therapy (IMRT). These strategies apply to delivery of IMRT to moving body anatomies that show relative displacement of OAR in close proximity to a tumor target. We formulated an efficient genetic algorithm which makes it po...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3132305
更新日期：2009-07-01 00:00:00
abstract：:Magnetic resonance (MR) measurements of relaxation times and diffusion coefficient in tissue have been demonstrated to be sensitive to biological changes induced by radiation therapy. We are currently using mouse models of human glioblastoma multiforme (GBM) to study tumour response to ionizing radiation by MRI at 9.4...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2965985
更新日期：2008-07-01 00:00:00
abstract：PURPOSE:Modern CT systems adjust X-ray flux accommodating for patient size to achieve certain image noise values. The effectiveness of this adaptation is an important aspect of CT performance and should ideally be characterized in the context of real patient cases. The objective of this study was to characterize CT per...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12172
更新日期：2017-06-01 00:00:00
abstract：:Contemporary reconstruction methods employed for clinical helical cone-beam computed tomography (CT) are analytical (noniterative) but mathematically nonexact, i.e., the reconstructed image contains so called cone-beam artifacts, especially for higher cone angles. Besides cone artifacts, these methods also suffer from...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2966353
更新日期：2008-09-01 00:00:00
abstract：PURPOSE:This study (1) examines a variety of real-world cases where systematic errors were not detected by widely accepted methods for IMRT/VMAT dosimetric accuracy evaluation, and (2) drills-down to identify failure modes and their corresponding means for detection, diagnosis, and mitigation. The primary goal of detai...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4826166
更新日期：2013-11-01 00:00:00
abstract：:A systems analysis of reduced dose mammography with scatter removal has quantitatively specified the relationships between the several parameters in mammography systems. While the results are only preliminary in the sense that they need to be proven experimentally, they do seem to provide a good feel for the nature of...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594540
更新日期：1979-03-01 00:00:00
abstract：PURPOSE:To correct for the deviations of the detector response when typical radiation detectors are used under non-reference conditions, factor kNR was calculated from the known energy dependence of the detector response at photon energies from 10 keV upwards and from clinical photon spectra within a large water phanto...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735184
更新日期：2012-06-01 00:00:00
abstract：:The purpose of this work is to calculate the dose perturbations due to the presence of iodine contrast media in catheter-based intravascular brachytherapy (IVBT). The EGSnrc Monte Carlo system was used to perform the calculation for the two most commonly used beta and gamma sources (90Sr and 192Ir as well as for a var...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1367279
更新日期：2001-05-01 00:00:00
abstract：PURPOSE:Quantitative SPECT imaging is limited by many factors, including penetration of high energy photons through the collimator. Even small peaks of high energy yield extensive contamination in the photopeak energy window. Rotating slat collimators typically offer a 40- to 50-fold increase in geometric detection eff...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3177312
更新日期：2009-09-01 00:00:00
abstract：:Reported MOSFET measurements concern mostly external radiotherapy and in vivo dosimetry. In this paper, we apply the technique for absolute dosimetry in the context of HDR brachytherapy using an 192Ir source. Measured radial dose rate distributions in water for different planes perpendicular to the source axis are pre...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2198168
更新日期：2006-06-01 00:00:00
abstract：:CEA TVS film is a therapy verification film that has been recently introduced in the North American market. This film features linear characteristic curves for photon energies from 137Cs to 18 MV as reported by Cheng and Das [Med. Phys. 23, 1225 (1996)]. In Saskatoon, TVS film was investigated for its application in t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598316
更新日期：1998-08-01 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
abstract：:Frequent and repeated imaging procedures such as those performed in image-guided radiotherapy (IGRT) programs may add significant dose to radiosensitive organs of radiotherapy patients. It has been shown that kV-CBCT results in doses to bone that are up to a factor of 3-4 higher than those in surrounding soft tissue. ...
journal_title：Medical physics
pub_type： 信件
doi：10.1118/1.3014197
更新日期：2008-12-01 00:00:00
abstract：:MR acoustic radiation force (ARF) imaging was developed for measuring tiSsue elastic properties using focused ultrasound to deliver a localized tissue motion. In this study, an imaging ultrasound transducer was mounted on the focused ultrasound transducer and ultrasound motion tracking was performed simultaneously to ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3120289
更新日期：2009-06-01 00:00:00
