Abstract:
PURPOSE:To compare reconstructed volumes calculated via planimetry and frustum algorithms in the context of stepped transrectal ultrasound (US) imaging, and to estimate the reconstruction error for prostate volumes. METHODS:Prostate contours for 40 permanent implant patients were delineated on magnetic resonance (MR) and transrectal US images by a radiation oncologist. Simulated images of ellipsoid and truncated cone geometrical objects were constructed to determine volume calculation accuracy. Simulation results were used to deduce the algorithm-associated error made when calculating transrectal US prostate volumes. RESULTS:For imaging without deliberate slice positioning, planimetry reconstruction was mostly accurate while the frustum algorithm underestimated the volume. The discrepancy was mostly due to the end slice reconstruction. For slice positioning that reflected US image acquisition, planimetry overestimated by half the superior slice volume on average while frustum underestimated by half the inferior slice volume. The estimated algorithm errors for prostate contours were 4% and -3%, respectively. CONCLUSIONS:The planimetry and frustum algorithms offer different interpretations for reconstruction and yield systematic differences in calculated volumes. Both algorithms introduce bias into transrectal US prostate volume determinations that may have clinical implications, planimetry overestimating and frustum underestimating the volume.
journal_name
Med Physjournal_title
Medical physicsauthors
Liu D,Usmani N,Sloboda RSdoi
10.1118/1.4789920subject
Has Abstractpub_date
2013-03-01 00:00:00pages
031705issue
3eissn
0094-2405issn
2473-4209journal_volume
40pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:We investigated the feasibility of proton tomosynthesis as daily positioning of patients and compared the results with photon tomosynthesis as an alternative to conventional portal imaging or on-board cone-beam computed tomography. METHODS:Dedicated photon-like proton beam using the passively scattered proton ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734898
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To add mathematical rigor to the merging phase of the recently published two-stage VMAT optimization method called VMERGE. Using an exact merging method, we are able to better characterize the tradeoff between delivery efficiency and dose quality. METHODS:VMERGE begins with an IMRT plan that uses 180 equi-spac...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735709
更新日期:2012-06-01 00:00:00
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::The widespread application of positron emission tomography (PET) in clinical oncology has driven this imaging technology into a number of new research and clinical arenas. Increasing numbers of patient scans have led to an urgent need for efficient data handling and the development of new image analysis techniques to ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2432404
更新日期:2007-02-01 00:00:00
abstract:PURPOSE:Since the first publications on intensity modulated radiation therapy (IMRT) in the early 1980s almost all efforts have been focused on fairly time consuming dynamic or segmental multileaf collimation. With narrow fast scanned photon beams, the flexibility and accuracy in beam shaping increases, not least in co...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3615059
更新日期:2011-08-01 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:PURPOSE:The study aims to investigate whether Nakagami parameters--estimated from the statistical distribution of the backscattered ultrasound radio-frequency (RF) signals--could provide a means for quantitative characterization of parotid-gland injury resulting from head-and-neck radiotherapy. METHODS:A preliminary c...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4862507
更新日期:2014-02-01 00:00:00
abstract:PURPOSE:Accurate detection of pulmonary nodules remains a technical challenge in computer-aided diagnosis systems because some nodules may adhere to the blood vessels or the lung wall, which have low contrast compared to the surrounding tissues. In this paper, the analysis of typical shape features of candidate nodules...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4907961
更新日期:2015-03-01 00:00:00
abstract:PURPOSE:The appearance of parenchymal∕stromal patterns in mammography have been characterized as having a Wiener power spectrum with an inverse power-law shape described by the exponential parameter, β. The amount of fibroglandular tissue, which can be quantified in terms of volumetric breast density (VBD), influences ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736422
更新日期:2012-08-01 00:00:00
abstract::The purpose of this paper is to develop a method that reduces the number of segments for intensity modulated arc therapy (IMAT) and intensity modulated radiotherapy (IMRT) for concave target volumes (TV). The aim was to utilize no more than two intensity levels per organ at risk (OAR) and to derive both optimal segmen...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1861161
更新日期:2005-03-01 00:00:00
abstract:PURPOSE:The fundamental nature of positron emission tomography (PET), as an event detection system, provides some flexibility for data handling, including retrospective data manipulation. The reorganization of acquisition data allows the emulation of new scans arising from identical radiotracer spatial distributions, b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13517
更新日期:2019-06-01 00:00:00
abstract::A modified neutron production target assembly has been developed to provide improved performance of the proton-cyclotron-based neutron radiotherapy facility at the University of Washington for applications involving neutron capture enhanced fast-neutron therapy. The new target produces a neutron beam that yields essen...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598839
更新日期:2000-02-01 00:00:00
abstract::Imaging parameters associated with a clinical magnetic resonance imaging (MRI) system, evaluated with the use of simple and inexpensive phantoms, are described in evaluation of a clinical MRI system. Images, obtained with a Diasonics 0.35-T MRI system using an elliptical whole-body radio frequency coil, are presented ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595894
更新日期:1986-07-01 00:00:00
abstract::Subsecond single-slice, multi-slice or cone-beam spiral computed tomography (SSCT, MSCT, CBCT) offer great potential for improving heart imaging. Together with the newly developed phase-correlated cardiac reconstruction algorithms 180 degrees MCD and 180 degrees MCI [Med. Phys. 27, 1881-1902 (2000)] or related algorit...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1487861
更新日期:2002-07-01 00:00:00
abstract::AAPM Magnetic Resonance Task Group #9 on proton magnetic resonance spectroscopy (MRS) in the brain was formed to provide a reference document for acquiring and processing proton (1H) MRS acquired from brain tissue. MRS is becoming a common adjunct to magnetic resonance imaging (MRI), especially for the differential di...
journal_title:Medical physics
pub_type: 指南,杂志文章,实务指引,评审
doi:10.1118/1.1501822
更新日期:2002-09-01 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::The physical characteristics of the interactions of megavoltage photons and electrons with matter provide distinct advantages, relative to low-energy (orthovoltage) x rays, that lead to better radiation dose distributions in patients. Use of these high-energy radiations has resulted in better patient care, which has b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596779
更新日期:1992-07-01 00:00:00
abstract:PURPOSE:The presence of respiratory motion during radiation treatment leads to degradation of the expected dose distribution, both for target coverage and healthy tissue sparing, particularly for techniques like pencil beam scanning proton therapy which have dynamic delivery systems. While tools exist to estimate this ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13182
更新日期:2018-11-01 00:00:00
abstract:PURPOSE:With increased use of handheld and tablet display devices for viewing medical images, methods for consistently measuring reflectivity of the devices are needed. In this note, the authors report on the characterization of diffuse reflections for handheld display devices including mobile phones and tablets using ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4887813
更新日期:2014-08-01 00:00:00
abstract:PURPOSE:Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3602456
更新日期:2011-07-01 00:00:00
abstract:PURPOSE:The purpose of this study is to adapt an equivalent source model originally developed for conventional CT Monte Carlo dose quantification to the radiation oncology context and validate its application for evaluating concomitant dose incurred by a kilovoltage (kV) cone-beam CT (CBCT) system integrated into a lin...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4823795
更新日期:2013-11-01 00:00:00
abstract::The surface radio frequency (rf) power absorption in human head and torso nuclear magnetic resonance (NMR) imaging experiments is estimated. The results are expressed as a function of the NMR frequency, the rf pulse length, and the pulse duty cycle, which are varied over six orders of magnitude for general applicabili...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595000
更新日期:1981-07-01 00:00:00
abstract:PURPOSE:We describe the acceptance testing, commissioning, periodic quality assurance, and workflow procedures developed for the first clinically implemented magnetic resonance imaging-guided radiation therapy (MR-IGRT) system for real-time tracking and beam control. METHODS:The system utilizes real-time cine imaging ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13002
更新日期:2018-05-28 00:00:00
abstract::The ability of Leksell GammaPlan to perform stereotactic space localizations with image sets where there is misalignment of the patient's head (stereotactic frame and fiducial apparatus) relative to the computed tomography (CT) scanner coordinate system was studied. Misalignment is sometimes necessary for patient comf...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2179751
更新日期:2006-04-01 00:00:00
abstract::This paper is concerned with the proposed Birmingham accelerator-based epithermal neutron beam for boron neutron capture therapy (BNCT). In particular, the option of producing a therapy beam at an orthogonal direction to the incoming protons is considered. Monte Carlo radiation transport simulations, both with and wit...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598479
更新日期:1999-01-01 00:00:00
abstract::A 4 x 500 mm2 "cloverleaf" low energy germanium detector array has been assembled for the purpose of in vivo bone lead measurement through x-ray fluorescence. Using 109Cd as an exciting source, results are reported from a leg phantom simulating measurement of lead in a human tibia. For high activity (4.0-4.4 GBq) and ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2436973
更新日期:2007-03-01 00:00:00
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:High-intensity focused ultrasound (HIFU) has been investigated for ablative therapy and drug enhancement for gene therapy and chemotherapy. The aim of this work is to explore the feasibility of pulsed focused ultrasound (pFUS) for cancer therapy using an in vivo animal model. METHODS:A clinical HIFU system (In...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4901352
更新日期:2014-12-01 00:00:00
abstract::Current generation electronic portal imaging devices (EPID) contain a 1.0 mm copper conversion plate to increase detection efficiency of a therapeutic megavoltage spectrum. When using these EPIDs for low-Z target imaging, the conversion plate largely attenuates the large populations of diagnostic energy photons, there...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4740105
更新日期:2012-07-01 00:00:00
abstract:PURPOSE:The purpose of this paper was to present a method of determining the dose profile of the beam bow-tie filter (BTF) without the need for fixing the x ray tube in a position or using special instruments or dosimeters other than the ordinary types of ion chambers used for CT dosimetry (e.g., Farmer chamber). METH...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13203
更新日期:2018-11-01 00:00:00